linux/fs/sysfs/file.c

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/*
* fs/sysfs/file.c - sysfs regular (text) file implementation
*
* Copyright (c) 2001-3 Patrick Mochel
* Copyright (c) 2007 SUSE Linux Products GmbH
* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
*
* This file is released under the GPLv2.
*
* Please see Documentation/filesystems/sysfs.txt for more information.
*/
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/kallsyms.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include "sysfs.h"
#include "../kernfs/kernfs-internal.h"
sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:21 +08:00
/*
* Determine ktype->sysfs_ops for the given kernfs_node. This function
* must be called while holding an active reference.
*/
static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
{
struct kobject *kobj = kn->parent->priv;
if (kn->flags & SYSFS_FLAG_LOCKDEP)
lockdep_assert_held(kn);
return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
}
/*
* Reads on sysfs are handled through seq_file, which takes care of hairy
* details like buffering and seeking. The following function pipes
* sysfs_ops->show() result through seq_file.
*/
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
struct kobject *kobj = of->kn->parent->priv;
const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
ssize_t count;
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
char *buf;
/* acquire buffer and ensure that it's >= PAGE_SIZE */
count = seq_get_buf(sf, &buf);
if (count < PAGE_SIZE) {
seq_commit(sf, -1);
return 0;
}
/*
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
* Invoke show(). Control may reach here via seq file lseek even
* if @ops->show() isn't implemented.
*/
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
if (ops->show) {
count = ops->show(kobj, of->kn->priv, buf);
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
if (count < 0)
return count;
}
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-14 02:45:16 +08:00
/*
* The code works fine with PAGE_SIZE return but it's likely to
* indicate truncated result or overflow in normal use cases.
*/
if (count >= (ssize_t)PAGE_SIZE) {
print_symbol("fill_read_buffer: %s returned bad count\n",
(unsigned long)ops->show);
/* Try to struggle along */
count = PAGE_SIZE - 1;
}
seq_commit(sf, count);
return 0;
}
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
struct bin_attribute *battr = of->kn->priv;
struct kobject *kobj = of->kn->parent->priv;
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
loff_t size = file_inode(of->file)->i_size;
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
if (!count)
return 0;
if (size) {
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
if (pos > size)
return 0;
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
if (pos + count > size)
count = size - pos;
}
sysfs, kernfs: prepare read path for kernfs We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:16 +08:00
if (!battr->read)
return -EIO;
return battr->read(of->file, kobj, battr, buf, pos, count);
}
/* kernfs write callback for regular sysfs files */
static ssize_t sysfs_kf_write(struct sysfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
struct kobject *kobj = of->kn->parent->priv;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-14 02:45:16 +08:00
if (!count)
return 0;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-14 02:45:16 +08:00
return ops->store(kobj, of->kn->priv, buf, count);
}
/* kernfs write callback for bin sysfs files */
static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
struct bin_attribute *battr = of->kn->priv;
struct kobject *kobj = of->kn->parent->priv;
loff_t size = file_inode(of->file)->i_size;
if (size) {
if (size <= pos)
return 0;
count = min_t(ssize_t, count, size - pos);
}
if (!count)
return 0;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-14 02:45:16 +08:00
if (!battr->write)
return -EIO;
return battr->write(of->file, kobj, battr, buf, pos, count);
}
static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
struct vm_area_struct *vma)
{
struct bin_attribute *battr = of->kn->priv;
struct kobject *kobj = of->kn->parent->priv;
return battr->mmap(of->file, kobj, battr, vma);
}
void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
{
struct kernfs_node *kn = kobj->sd, *tmp;
if (kn && dir)
kn = kernfs_find_and_get(kn, dir);
else
kernfs_get(kn);
if (kn && attr) {
tmp = kernfs_find_and_get(kn, attr);
kernfs_put(kn);
kn = tmp;
}
if (kn) {
kernfs_notify(kn);
kernfs_put(kn);
}
}
EXPORT_SYMBOL_GPL(sysfs_notify);
sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:21 +08:00
static const struct kernfs_ops sysfs_file_kfops_empty = {
};
static const struct kernfs_ops sysfs_file_kfops_ro = {
.seq_show = sysfs_kf_seq_show,
};
static const struct kernfs_ops sysfs_file_kfops_wo = {
.write = sysfs_kf_write,
};
static const struct kernfs_ops sysfs_file_kfops_rw = {
.seq_show = sysfs_kf_seq_show,
.write = sysfs_kf_write,
};
static const struct kernfs_ops sysfs_bin_kfops_ro = {
.read = sysfs_kf_bin_read,
};
static const struct kernfs_ops sysfs_bin_kfops_wo = {
.write = sysfs_kf_bin_write,
};
static const struct kernfs_ops sysfs_bin_kfops_rw = {
.read = sysfs_kf_bin_read,
.write = sysfs_kf_bin_write,
sysfs: bail early from kernfs_file_mmap() to avoid spurious lockdep warning This is v3.14 fix for the same issue that a8b14744429f ("sysfs: give different locking key to regular and bin files") addresses for v3.13. Due to the extensive kernfs reorganization in v3.14 branch, the same fix couldn't be ported as-is. The v3.13 fix was ignored while merging it into v3.14 branch. 027a485d12e0 ("sysfs: use a separate locking class for open files depending on mmap") assigned different lockdep key to sysfs_open_file->mutex depending on whether the file implements mmap or not in an attempt to avoid spurious lockdep warning caused by merging of regular and bin file paths. While this restored some of the original behavior of using different locks (at least lockdep is concerned) for the different clases of files. The restoration wasn't full because now the lockdep key assignment depends on whether the file has mmap or not instead of whether it's a regular file or not. This means that bin files which don't implement mmap will get assigned the same lockdep class as regular files. This is problematic because file_operations for bin files still implements the mmap file operation and checking whether the sysfs file actually implements mmap happens in the file operation after grabbing @sysfs_open_file->mutex. We still end up adding locking dependency from mmap locking to sysfs_open_file->mutex to the regular file mutex which triggers spurious circular locking warning. For v3.13, a8b14744429f ("sysfs: give different locking key to regular and bin files") fixed it by giving sysfs_open_file->mutex different lockdep keys depending on whether the file is regular or bin instead of whether mmap exists or not; however, due to the way sysfs is now layered behind kernfs, this approach is no longer viable. kernfs can tell whether a sysfs node has mmap implemented or not but can't tell whether a bin file from a regular one. This patch updates kernfs such that kernfs_file_mmap() checks SYSFS_FLAG_HAS_MMAP and bail before grabbing sysfs_open_file->mutex so that it doesn't add spurious locking dependency from mmap to sysfs_open_file->mutex and changes sysfs so that it specifies kernfs_ops->mmap iff the sysfs file implements mmap. Combined, this ensures that sysfs_open_file->mutex is grabbed under mmap path iff the sysfs file actually implements mmap. As sysfs_open_file->mutex is already given a different lockdep key if mmap is implemented, this removes the spurious locking dependency. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@redhat.com> Link: http://lkml.kernel.org/g/20131203184324.GA11320@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-10 22:29:17 +08:00
};
static const struct kernfs_ops sysfs_bin_kfops_mmap = {
.read = sysfs_kf_bin_read,
.write = sysfs_kf_bin_write,
sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:21 +08:00
.mmap = sysfs_kf_bin_mmap,
};
int sysfs_add_file_mode_ns(struct kernfs_node *parent,
const struct attribute *attr, bool is_bin,
umode_t mode, const void *ns)
{
struct lock_class_key *key = NULL;
sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:21 +08:00
const struct kernfs_ops *ops;
struct kernfs_node *kn;
loff_t size;
if (!is_bin) {
struct kobject *kobj = parent->priv;
sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:21 +08:00
const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
/* every kobject with an attribute needs a ktype assigned */
if (WARN(!sysfs_ops, KERN_ERR
"missing sysfs attribute operations for kobject: %s\n",
kobject_name(kobj)))
return -EINVAL;
if (sysfs_ops->show && sysfs_ops->store)
ops = &sysfs_file_kfops_rw;
else if (sysfs_ops->show)
ops = &sysfs_file_kfops_ro;
else if (sysfs_ops->store)
ops = &sysfs_file_kfops_wo;
else
ops = &sysfs_file_kfops_empty;
size = PAGE_SIZE;
sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:21 +08:00
} else {
struct bin_attribute *battr = (void *)attr;
sysfs: bail early from kernfs_file_mmap() to avoid spurious lockdep warning This is v3.14 fix for the same issue that a8b14744429f ("sysfs: give different locking key to regular and bin files") addresses for v3.13. Due to the extensive kernfs reorganization in v3.14 branch, the same fix couldn't be ported as-is. The v3.13 fix was ignored while merging it into v3.14 branch. 027a485d12e0 ("sysfs: use a separate locking class for open files depending on mmap") assigned different lockdep key to sysfs_open_file->mutex depending on whether the file implements mmap or not in an attempt to avoid spurious lockdep warning caused by merging of regular and bin file paths. While this restored some of the original behavior of using different locks (at least lockdep is concerned) for the different clases of files. The restoration wasn't full because now the lockdep key assignment depends on whether the file has mmap or not instead of whether it's a regular file or not. This means that bin files which don't implement mmap will get assigned the same lockdep class as regular files. This is problematic because file_operations for bin files still implements the mmap file operation and checking whether the sysfs file actually implements mmap happens in the file operation after grabbing @sysfs_open_file->mutex. We still end up adding locking dependency from mmap locking to sysfs_open_file->mutex to the regular file mutex which triggers spurious circular locking warning. For v3.13, a8b14744429f ("sysfs: give different locking key to regular and bin files") fixed it by giving sysfs_open_file->mutex different lockdep keys depending on whether the file is regular or bin instead of whether mmap exists or not; however, due to the way sysfs is now layered behind kernfs, this approach is no longer viable. kernfs can tell whether a sysfs node has mmap implemented or not but can't tell whether a bin file from a regular one. This patch updates kernfs such that kernfs_file_mmap() checks SYSFS_FLAG_HAS_MMAP and bail before grabbing sysfs_open_file->mutex so that it doesn't add spurious locking dependency from mmap to sysfs_open_file->mutex and changes sysfs so that it specifies kernfs_ops->mmap iff the sysfs file implements mmap. Combined, this ensures that sysfs_open_file->mutex is grabbed under mmap path iff the sysfs file actually implements mmap. As sysfs_open_file->mutex is already given a different lockdep key if mmap is implemented, this removes the spurious locking dependency. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@redhat.com> Link: http://lkml.kernel.org/g/20131203184324.GA11320@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-10 22:29:17 +08:00
if (battr->mmap)
ops = &sysfs_bin_kfops_mmap;
else if (battr->read && battr->write)
sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:21 +08:00
ops = &sysfs_bin_kfops_rw;
else if (battr->read)
ops = &sysfs_bin_kfops_ro;
else if (battr->write)
ops = &sysfs_bin_kfops_wo;
else
ops = &sysfs_file_kfops_empty;
size = battr->size;
sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 03:54:21 +08:00
}
#ifdef CONFIG_DEBUG_LOCK_ALLOC
if (!attr->ignore_lockdep)
key = attr->key ?: (struct lock_class_key *)&attr->skey;
#endif
kn = kernfs_create_file_ns_key(parent, attr->name, mode, size,
ops, (void *)attr, ns, key);
if (IS_ERR(kn)) {
if (PTR_ERR(kn) == -EEXIST)
sysfs_warn_dup(parent, attr->name);
return PTR_ERR(kn);
}
return 0;
}
int sysfs_add_file(struct kernfs_node *parent, const struct attribute *attr,
bool is_bin)
{
return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL);
}
/**
sysfs: make attr namespace interface less convoluted sysfs ns (namespace) implementation became more convoluted than necessary while trying to hide ns information from visible interface. The relatively recent attr ns support is a good example. * attr ns tag is determined by sysfs_ops->namespace() callback while dir tag is determined by kobj_type->namespace(). The placement is arbitrary. * Instead of performing operations with explicit ns tag, the namespace callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(), class_attr_namespace(), class_attr->namespace(). It's not simpler in any sense. The only thing this convolution does is traversing the whole stack backwards. The namespace callbacks are unncessary because the operations involved are inherently synchronous. The information can be provided in in straight-forward top-down direction and reversing that direction is unnecessary and against basic design principles. This backward interface is unnecessarily convoluted and hinders properly separating out sysfs from driver model / kobject for proper layering. This patch updates attr ns support such that * sysfs_ops->namespace() and class_attr->namespace() are dropped. * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are added and sysfs_{create|remove}_file() are now simple wrappers around the ns aware functions. * ns handling is dropped from sysfs_chmod_file(). Nobody uses it at this point. sysfs_chmod_file_ns() can be added later if necessary. * Explicit @ns is propagated through class_{create|remove}_file_ns() and netdev_class_{create|remove}_file_ns(). * driver/net/bonding which is currently the only user of attr namespace is updated to use netdev_class_{create|remove}_file_ns() with @bh->net as the ns tag instead of using the namespace callback. This patch should be an equivalent conversion without any functional difference. It makes the code easier to follow, reduces lines of code a bit and helps proper separation and layering. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-12 10:29:04 +08:00
* sysfs_create_file_ns - create an attribute file for an object with custom ns
* @kobj: object we're creating for
* @attr: attribute descriptor
* @ns: namespace the new file should belong to
*/
sysfs: make attr namespace interface less convoluted sysfs ns (namespace) implementation became more convoluted than necessary while trying to hide ns information from visible interface. The relatively recent attr ns support is a good example. * attr ns tag is determined by sysfs_ops->namespace() callback while dir tag is determined by kobj_type->namespace(). The placement is arbitrary. * Instead of performing operations with explicit ns tag, the namespace callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(), class_attr_namespace(), class_attr->namespace(). It's not simpler in any sense. The only thing this convolution does is traversing the whole stack backwards. The namespace callbacks are unncessary because the operations involved are inherently synchronous. The information can be provided in in straight-forward top-down direction and reversing that direction is unnecessary and against basic design principles. This backward interface is unnecessarily convoluted and hinders properly separating out sysfs from driver model / kobject for proper layering. This patch updates attr ns support such that * sysfs_ops->namespace() and class_attr->namespace() are dropped. * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are added and sysfs_{create|remove}_file() are now simple wrappers around the ns aware functions. * ns handling is dropped from sysfs_chmod_file(). Nobody uses it at this point. sysfs_chmod_file_ns() can be added later if necessary. * Explicit @ns is propagated through class_{create|remove}_file_ns() and netdev_class_{create|remove}_file_ns(). * driver/net/bonding which is currently the only user of attr namespace is updated to use netdev_class_{create|remove}_file_ns() with @bh->net as the ns tag instead of using the namespace callback. This patch should be an equivalent conversion without any functional difference. It makes the code easier to follow, reduces lines of code a bit and helps proper separation and layering. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-12 10:29:04 +08:00
int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
const void *ns)
{
BUG_ON(!kobj || !kobj->sd || !attr);
return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);
}
sysfs: make attr namespace interface less convoluted sysfs ns (namespace) implementation became more convoluted than necessary while trying to hide ns information from visible interface. The relatively recent attr ns support is a good example. * attr ns tag is determined by sysfs_ops->namespace() callback while dir tag is determined by kobj_type->namespace(). The placement is arbitrary. * Instead of performing operations with explicit ns tag, the namespace callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(), class_attr_namespace(), class_attr->namespace(). It's not simpler in any sense. The only thing this convolution does is traversing the whole stack backwards. The namespace callbacks are unncessary because the operations involved are inherently synchronous. The information can be provided in in straight-forward top-down direction and reversing that direction is unnecessary and against basic design principles. This backward interface is unnecessarily convoluted and hinders properly separating out sysfs from driver model / kobject for proper layering. This patch updates attr ns support such that * sysfs_ops->namespace() and class_attr->namespace() are dropped. * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are added and sysfs_{create|remove}_file() are now simple wrappers around the ns aware functions. * ns handling is dropped from sysfs_chmod_file(). Nobody uses it at this point. sysfs_chmod_file_ns() can be added later if necessary. * Explicit @ns is propagated through class_{create|remove}_file_ns() and netdev_class_{create|remove}_file_ns(). * driver/net/bonding which is currently the only user of attr namespace is updated to use netdev_class_{create|remove}_file_ns() with @bh->net as the ns tag instead of using the namespace callback. This patch should be an equivalent conversion without any functional difference. It makes the code easier to follow, reduces lines of code a bit and helps proper separation and layering. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-12 10:29:04 +08:00
EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
{
int err = 0;
int i;
for (i = 0; ptr[i] && !err; i++)
err = sysfs_create_file(kobj, ptr[i]);
if (err)
while (--i >= 0)
sysfs_remove_file(kobj, ptr[i]);
return err;
}
EXPORT_SYMBOL_GPL(sysfs_create_files);
/**
* sysfs_add_file_to_group - add an attribute file to a pre-existing group.
* @kobj: object we're acting for.
* @attr: attribute descriptor.
* @group: group name.
*/
int sysfs_add_file_to_group(struct kobject *kobj,
const struct attribute *attr, const char *group)
{
struct kernfs_node *parent;
int error;
if (group) {
parent = kernfs_find_and_get(kobj->sd, group);
} else {
parent = kobj->sd;
kernfs_get(parent);
}
if (!parent)
return -ENOENT;
error = sysfs_add_file(parent, attr, false);
kernfs_put(parent);
return error;
}
EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
/**
* sysfs_chmod_file - update the modified mode value on an object attribute.
* @kobj: object we're acting for.
* @attr: attribute descriptor.
* @mode: file permissions.
*
*/
int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
umode_t mode)
{
struct kernfs_node *kn;
struct iattr newattrs;
int rc;
kn = kernfs_find_and_get(kobj->sd, attr->name);
if (!kn)
return -ENOENT;
newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE;
rc = kernfs_setattr(kn, &newattrs);
kernfs_put(kn);
return rc;
}
EXPORT_SYMBOL_GPL(sysfs_chmod_file);
/**
sysfs: make attr namespace interface less convoluted sysfs ns (namespace) implementation became more convoluted than necessary while trying to hide ns information from visible interface. The relatively recent attr ns support is a good example. * attr ns tag is determined by sysfs_ops->namespace() callback while dir tag is determined by kobj_type->namespace(). The placement is arbitrary. * Instead of performing operations with explicit ns tag, the namespace callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(), class_attr_namespace(), class_attr->namespace(). It's not simpler in any sense. The only thing this convolution does is traversing the whole stack backwards. The namespace callbacks are unncessary because the operations involved are inherently synchronous. The information can be provided in in straight-forward top-down direction and reversing that direction is unnecessary and against basic design principles. This backward interface is unnecessarily convoluted and hinders properly separating out sysfs from driver model / kobject for proper layering. This patch updates attr ns support such that * sysfs_ops->namespace() and class_attr->namespace() are dropped. * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are added and sysfs_{create|remove}_file() are now simple wrappers around the ns aware functions. * ns handling is dropped from sysfs_chmod_file(). Nobody uses it at this point. sysfs_chmod_file_ns() can be added later if necessary. * Explicit @ns is propagated through class_{create|remove}_file_ns() and netdev_class_{create|remove}_file_ns(). * driver/net/bonding which is currently the only user of attr namespace is updated to use netdev_class_{create|remove}_file_ns() with @bh->net as the ns tag instead of using the namespace callback. This patch should be an equivalent conversion without any functional difference. It makes the code easier to follow, reduces lines of code a bit and helps proper separation and layering. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-12 10:29:04 +08:00
* sysfs_remove_file_ns - remove an object attribute with a custom ns tag
* @kobj: object we're acting for
* @attr: attribute descriptor
* @ns: namespace tag of the file to remove
*
sysfs: make attr namespace interface less convoluted sysfs ns (namespace) implementation became more convoluted than necessary while trying to hide ns information from visible interface. The relatively recent attr ns support is a good example. * attr ns tag is determined by sysfs_ops->namespace() callback while dir tag is determined by kobj_type->namespace(). The placement is arbitrary. * Instead of performing operations with explicit ns tag, the namespace callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(), class_attr_namespace(), class_attr->namespace(). It's not simpler in any sense. The only thing this convolution does is traversing the whole stack backwards. The namespace callbacks are unncessary because the operations involved are inherently synchronous. The information can be provided in in straight-forward top-down direction and reversing that direction is unnecessary and against basic design principles. This backward interface is unnecessarily convoluted and hinders properly separating out sysfs from driver model / kobject for proper layering. This patch updates attr ns support such that * sysfs_ops->namespace() and class_attr->namespace() are dropped. * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are added and sysfs_{create|remove}_file() are now simple wrappers around the ns aware functions. * ns handling is dropped from sysfs_chmod_file(). Nobody uses it at this point. sysfs_chmod_file_ns() can be added later if necessary. * Explicit @ns is propagated through class_{create|remove}_file_ns() and netdev_class_{create|remove}_file_ns(). * driver/net/bonding which is currently the only user of attr namespace is updated to use netdev_class_{create|remove}_file_ns() with @bh->net as the ns tag instead of using the namespace callback. This patch should be an equivalent conversion without any functional difference. It makes the code easier to follow, reduces lines of code a bit and helps proper separation and layering. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-12 10:29:04 +08:00
* Hash the attribute name and namespace tag and kill the victim.
*/
sysfs: make attr namespace interface less convoluted sysfs ns (namespace) implementation became more convoluted than necessary while trying to hide ns information from visible interface. The relatively recent attr ns support is a good example. * attr ns tag is determined by sysfs_ops->namespace() callback while dir tag is determined by kobj_type->namespace(). The placement is arbitrary. * Instead of performing operations with explicit ns tag, the namespace callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(), class_attr_namespace(), class_attr->namespace(). It's not simpler in any sense. The only thing this convolution does is traversing the whole stack backwards. The namespace callbacks are unncessary because the operations involved are inherently synchronous. The information can be provided in in straight-forward top-down direction and reversing that direction is unnecessary and against basic design principles. This backward interface is unnecessarily convoluted and hinders properly separating out sysfs from driver model / kobject for proper layering. This patch updates attr ns support such that * sysfs_ops->namespace() and class_attr->namespace() are dropped. * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are added and sysfs_{create|remove}_file() are now simple wrappers around the ns aware functions. * ns handling is dropped from sysfs_chmod_file(). Nobody uses it at this point. sysfs_chmod_file_ns() can be added later if necessary. * Explicit @ns is propagated through class_{create|remove}_file_ns() and netdev_class_{create|remove}_file_ns(). * driver/net/bonding which is currently the only user of attr namespace is updated to use netdev_class_{create|remove}_file_ns() with @bh->net as the ns tag instead of using the namespace callback. This patch should be an equivalent conversion without any functional difference. It makes the code easier to follow, reduces lines of code a bit and helps proper separation and layering. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-12 10:29:04 +08:00
void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
const void *ns)
{
struct kernfs_node *parent = kobj->sd;
kernfs_remove_by_name_ns(parent, attr->name, ns);
}
sysfs: make attr namespace interface less convoluted sysfs ns (namespace) implementation became more convoluted than necessary while trying to hide ns information from visible interface. The relatively recent attr ns support is a good example. * attr ns tag is determined by sysfs_ops->namespace() callback while dir tag is determined by kobj_type->namespace(). The placement is arbitrary. * Instead of performing operations with explicit ns tag, the namespace callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(), class_attr_namespace(), class_attr->namespace(). It's not simpler in any sense. The only thing this convolution does is traversing the whole stack backwards. The namespace callbacks are unncessary because the operations involved are inherently synchronous. The information can be provided in in straight-forward top-down direction and reversing that direction is unnecessary and against basic design principles. This backward interface is unnecessarily convoluted and hinders properly separating out sysfs from driver model / kobject for proper layering. This patch updates attr ns support such that * sysfs_ops->namespace() and class_attr->namespace() are dropped. * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are added and sysfs_{create|remove}_file() are now simple wrappers around the ns aware functions. * ns handling is dropped from sysfs_chmod_file(). Nobody uses it at this point. sysfs_chmod_file_ns() can be added later if necessary. * Explicit @ns is propagated through class_{create|remove}_file_ns() and netdev_class_{create|remove}_file_ns(). * driver/net/bonding which is currently the only user of attr namespace is updated to use netdev_class_{create|remove}_file_ns() with @bh->net as the ns tag instead of using the namespace callback. This patch should be an equivalent conversion without any functional difference. It makes the code easier to follow, reduces lines of code a bit and helps proper separation and layering. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-12 10:29:04 +08:00
EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);
void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr)
{
int i;
for (i = 0; ptr[i]; i++)
sysfs_remove_file(kobj, ptr[i]);
}
EXPORT_SYMBOL_GPL(sysfs_remove_files);
/**
* sysfs_remove_file_from_group - remove an attribute file from a group.
* @kobj: object we're acting for.
* @attr: attribute descriptor.
* @group: group name.
*/
void sysfs_remove_file_from_group(struct kobject *kobj,
const struct attribute *attr, const char *group)
{
struct kernfs_node *parent;
if (group) {
parent = kernfs_find_and_get(kobj->sd, group);
} else {
parent = kobj->sd;
kernfs_get(parent);
}
if (parent) {
kernfs_remove_by_name(parent, attr->name);
kernfs_put(parent);
}
}
EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
/**
* sysfs_create_bin_file - create binary file for object.
* @kobj: object.
* @attr: attribute descriptor.
*/
int sysfs_create_bin_file(struct kobject *kobj,
const struct bin_attribute *attr)
{
BUG_ON(!kobj || !kobj->sd || !attr);
return sysfs_add_file(kobj->sd, &attr->attr, true);
}
EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
/**
* sysfs_remove_bin_file - remove binary file for object.
* @kobj: object.
* @attr: attribute descriptor.
*/
void sysfs_remove_bin_file(struct kobject *kobj,
const struct bin_attribute *attr)
{
kernfs_remove_by_name(kobj->sd, attr->attr.name);
}
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
struct sysfs_schedule_callback_struct {
struct list_head workq_list;
struct kobject *kobj;
void (*func)(void *);
void *data;
struct module *owner;
struct work_struct work;
};
sysfs: don't use global workqueue in sysfs_schedule_callback() A sysfs attribute using sysfs_schedule_callback() to commit suicide may end up calling device_unregister(), which will eventually call a driver's ->remove function. Drivers may call flush_scheduled_work() in their shutdown routines, in which case lockdep will complain with something like the following: ============================================= [ INFO: possible recursive locking detected ] 2.6.29-rc8-kk #1 --------------------------------------------- events/4/56 is trying to acquire lock: (events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0 but task is already holding lock: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 other info that might help us debug this: 3 locks held by events/4/56: #0: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #1: (&ss->work){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #2: (pci_remove_rescan_mutex){--..}, at: [<ffffffff803c10d1>] remove_callback+0x21/0x40 stack backtrace: Pid: 56, comm: events/4 Not tainted 2.6.29-rc8-kk #1 Call Trace: [<ffffffff8026dfcd>] validate_chain+0xb7d/0x1260 [<ffffffff8026eade>] __lock_acquire+0x42e/0xa40 [<ffffffff8026f148>] lock_acquire+0x58/0x80 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff8025800d>] flush_workqueue+0x4d/0xa0 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff80258070>] flush_scheduled_work+0x10/0x20 [<ffffffffa0144065>] e1000_remove+0x55/0xfe [e1000e] [<ffffffff8033ee30>] ? sysfs_schedule_callback_work+0x0/0x50 [<ffffffff803bfeb2>] pci_device_remove+0x32/0x70 [<ffffffff80441da9>] __device_release_driver+0x59/0x90 [<ffffffff80441edb>] device_release_driver+0x2b/0x40 [<ffffffff804419d6>] bus_remove_device+0xa6/0x120 [<ffffffff8043e46b>] device_del+0x12b/0x190 [<ffffffff8043e4f6>] device_unregister+0x26/0x70 [<ffffffff803ba969>] pci_stop_dev+0x49/0x60 [<ffffffff803baab0>] pci_remove_bus_device+0x40/0xc0 [<ffffffff803c10d9>] remove_callback+0x29/0x40 [<ffffffff8033ee4f>] sysfs_schedule_callback_work+0x1f/0x50 [<ffffffff8025769a>] run_workqueue+0x15a/0x230 [<ffffffff80257648>] ? run_workqueue+0x108/0x230 [<ffffffff8025846f>] worker_thread+0x9f/0x100 [<ffffffff8025bce0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff802583d0>] ? worker_thread+0x0/0x100 [<ffffffff8025b89d>] kthread+0x4d/0x80 [<ffffffff8020d4ba>] child_rip+0xa/0x20 [<ffffffff8020cebc>] ? restore_args+0x0/0x30 [<ffffffff8025b850>] ? kthread+0x0/0x80 [<ffffffff8020d4b0>] ? child_rip+0x0/0x20 Although we know that the device_unregister path will never acquire a lock that a driver might try to acquire in its ->remove, in general we should never attempt to flush a workqueue from within the same workqueue, and lockdep rightly complains. So as long as sysfs attributes cannot commit suicide directly and we are stuck with this callback mechanism, put the sysfs callbacks on their own workqueue instead of the global one. This has the side benefit that if a suicidal sysfs attribute kicks off a long chain of ->remove callbacks, we no longer induce a long delay on the global queue. This also fixes a missing module_put in the error path introduced by sysfs-only-allow-one-scheduled-removal-callback-per-kobj.patch. We never destroy the workqueue, but I'm not sure that's a problem. Reported-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Tested-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Signed-off-by: Alex Chiang <achiang@hp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-03-26 05:11:36 +08:00
static struct workqueue_struct *sysfs_workqueue;
static DEFINE_MUTEX(sysfs_workq_mutex);
static LIST_HEAD(sysfs_workq);
static void sysfs_schedule_callback_work(struct work_struct *work)
{
struct sysfs_schedule_callback_struct *ss = container_of(work,
struct sysfs_schedule_callback_struct, work);
(ss->func)(ss->data);
kobject_put(ss->kobj);
module_put(ss->owner);
mutex_lock(&sysfs_workq_mutex);
list_del(&ss->workq_list);
mutex_unlock(&sysfs_workq_mutex);
kfree(ss);
}
/**
* sysfs_schedule_callback - helper to schedule a callback for a kobject
* @kobj: object we're acting for.
* @func: callback function to invoke later.
* @data: argument to pass to @func.
* @owner: module owning the callback code
*
* sysfs attribute methods must not unregister themselves or their parent
* kobject (which would amount to the same thing). Attempts to do so will
* deadlock, since unregistration is mutually exclusive with driver
* callbacks.
*
* Instead methods can call this routine, which will attempt to allocate
* and schedule a workqueue request to call back @func with @data as its
* argument in the workqueue's process context. @kobj will be pinned
* until @func returns.
*
* Returns 0 if the request was submitted, -ENOMEM if storage could not
* be allocated, -ENODEV if a reference to @owner isn't available,
* -EAGAIN if a callback has already been scheduled for @kobj.
*/
int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
void *data, struct module *owner)
{
struct sysfs_schedule_callback_struct *ss, *tmp;
if (!try_module_get(owner))
return -ENODEV;
mutex_lock(&sysfs_workq_mutex);
list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list)
if (ss->kobj == kobj) {
sysfs: don't use global workqueue in sysfs_schedule_callback() A sysfs attribute using sysfs_schedule_callback() to commit suicide may end up calling device_unregister(), which will eventually call a driver's ->remove function. Drivers may call flush_scheduled_work() in their shutdown routines, in which case lockdep will complain with something like the following: ============================================= [ INFO: possible recursive locking detected ] 2.6.29-rc8-kk #1 --------------------------------------------- events/4/56 is trying to acquire lock: (events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0 but task is already holding lock: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 other info that might help us debug this: 3 locks held by events/4/56: #0: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #1: (&ss->work){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #2: (pci_remove_rescan_mutex){--..}, at: [<ffffffff803c10d1>] remove_callback+0x21/0x40 stack backtrace: Pid: 56, comm: events/4 Not tainted 2.6.29-rc8-kk #1 Call Trace: [<ffffffff8026dfcd>] validate_chain+0xb7d/0x1260 [<ffffffff8026eade>] __lock_acquire+0x42e/0xa40 [<ffffffff8026f148>] lock_acquire+0x58/0x80 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff8025800d>] flush_workqueue+0x4d/0xa0 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff80258070>] flush_scheduled_work+0x10/0x20 [<ffffffffa0144065>] e1000_remove+0x55/0xfe [e1000e] [<ffffffff8033ee30>] ? sysfs_schedule_callback_work+0x0/0x50 [<ffffffff803bfeb2>] pci_device_remove+0x32/0x70 [<ffffffff80441da9>] __device_release_driver+0x59/0x90 [<ffffffff80441edb>] device_release_driver+0x2b/0x40 [<ffffffff804419d6>] bus_remove_device+0xa6/0x120 [<ffffffff8043e46b>] device_del+0x12b/0x190 [<ffffffff8043e4f6>] device_unregister+0x26/0x70 [<ffffffff803ba969>] pci_stop_dev+0x49/0x60 [<ffffffff803baab0>] pci_remove_bus_device+0x40/0xc0 [<ffffffff803c10d9>] remove_callback+0x29/0x40 [<ffffffff8033ee4f>] sysfs_schedule_callback_work+0x1f/0x50 [<ffffffff8025769a>] run_workqueue+0x15a/0x230 [<ffffffff80257648>] ? run_workqueue+0x108/0x230 [<ffffffff8025846f>] worker_thread+0x9f/0x100 [<ffffffff8025bce0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff802583d0>] ? worker_thread+0x0/0x100 [<ffffffff8025b89d>] kthread+0x4d/0x80 [<ffffffff8020d4ba>] child_rip+0xa/0x20 [<ffffffff8020cebc>] ? restore_args+0x0/0x30 [<ffffffff8025b850>] ? kthread+0x0/0x80 [<ffffffff8020d4b0>] ? child_rip+0x0/0x20 Although we know that the device_unregister path will never acquire a lock that a driver might try to acquire in its ->remove, in general we should never attempt to flush a workqueue from within the same workqueue, and lockdep rightly complains. So as long as sysfs attributes cannot commit suicide directly and we are stuck with this callback mechanism, put the sysfs callbacks on their own workqueue instead of the global one. This has the side benefit that if a suicidal sysfs attribute kicks off a long chain of ->remove callbacks, we no longer induce a long delay on the global queue. This also fixes a missing module_put in the error path introduced by sysfs-only-allow-one-scheduled-removal-callback-per-kobj.patch. We never destroy the workqueue, but I'm not sure that's a problem. Reported-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Tested-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Signed-off-by: Alex Chiang <achiang@hp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-03-26 05:11:36 +08:00
module_put(owner);
mutex_unlock(&sysfs_workq_mutex);
return -EAGAIN;
}
mutex_unlock(&sysfs_workq_mutex);
sysfs: don't use global workqueue in sysfs_schedule_callback() A sysfs attribute using sysfs_schedule_callback() to commit suicide may end up calling device_unregister(), which will eventually call a driver's ->remove function. Drivers may call flush_scheduled_work() in their shutdown routines, in which case lockdep will complain with something like the following: ============================================= [ INFO: possible recursive locking detected ] 2.6.29-rc8-kk #1 --------------------------------------------- events/4/56 is trying to acquire lock: (events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0 but task is already holding lock: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 other info that might help us debug this: 3 locks held by events/4/56: #0: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #1: (&ss->work){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #2: (pci_remove_rescan_mutex){--..}, at: [<ffffffff803c10d1>] remove_callback+0x21/0x40 stack backtrace: Pid: 56, comm: events/4 Not tainted 2.6.29-rc8-kk #1 Call Trace: [<ffffffff8026dfcd>] validate_chain+0xb7d/0x1260 [<ffffffff8026eade>] __lock_acquire+0x42e/0xa40 [<ffffffff8026f148>] lock_acquire+0x58/0x80 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff8025800d>] flush_workqueue+0x4d/0xa0 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff80258070>] flush_scheduled_work+0x10/0x20 [<ffffffffa0144065>] e1000_remove+0x55/0xfe [e1000e] [<ffffffff8033ee30>] ? sysfs_schedule_callback_work+0x0/0x50 [<ffffffff803bfeb2>] pci_device_remove+0x32/0x70 [<ffffffff80441da9>] __device_release_driver+0x59/0x90 [<ffffffff80441edb>] device_release_driver+0x2b/0x40 [<ffffffff804419d6>] bus_remove_device+0xa6/0x120 [<ffffffff8043e46b>] device_del+0x12b/0x190 [<ffffffff8043e4f6>] device_unregister+0x26/0x70 [<ffffffff803ba969>] pci_stop_dev+0x49/0x60 [<ffffffff803baab0>] pci_remove_bus_device+0x40/0xc0 [<ffffffff803c10d9>] remove_callback+0x29/0x40 [<ffffffff8033ee4f>] sysfs_schedule_callback_work+0x1f/0x50 [<ffffffff8025769a>] run_workqueue+0x15a/0x230 [<ffffffff80257648>] ? run_workqueue+0x108/0x230 [<ffffffff8025846f>] worker_thread+0x9f/0x100 [<ffffffff8025bce0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff802583d0>] ? worker_thread+0x0/0x100 [<ffffffff8025b89d>] kthread+0x4d/0x80 [<ffffffff8020d4ba>] child_rip+0xa/0x20 [<ffffffff8020cebc>] ? restore_args+0x0/0x30 [<ffffffff8025b850>] ? kthread+0x0/0x80 [<ffffffff8020d4b0>] ? child_rip+0x0/0x20 Although we know that the device_unregister path will never acquire a lock that a driver might try to acquire in its ->remove, in general we should never attempt to flush a workqueue from within the same workqueue, and lockdep rightly complains. So as long as sysfs attributes cannot commit suicide directly and we are stuck with this callback mechanism, put the sysfs callbacks on their own workqueue instead of the global one. This has the side benefit that if a suicidal sysfs attribute kicks off a long chain of ->remove callbacks, we no longer induce a long delay on the global queue. This also fixes a missing module_put in the error path introduced by sysfs-only-allow-one-scheduled-removal-callback-per-kobj.patch. We never destroy the workqueue, but I'm not sure that's a problem. Reported-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Tested-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Signed-off-by: Alex Chiang <achiang@hp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-03-26 05:11:36 +08:00
if (sysfs_workqueue == NULL) {
sysfs_workqueue = create_singlethread_workqueue("sysfsd");
sysfs: don't use global workqueue in sysfs_schedule_callback() A sysfs attribute using sysfs_schedule_callback() to commit suicide may end up calling device_unregister(), which will eventually call a driver's ->remove function. Drivers may call flush_scheduled_work() in their shutdown routines, in which case lockdep will complain with something like the following: ============================================= [ INFO: possible recursive locking detected ] 2.6.29-rc8-kk #1 --------------------------------------------- events/4/56 is trying to acquire lock: (events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0 but task is already holding lock: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 other info that might help us debug this: 3 locks held by events/4/56: #0: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #1: (&ss->work){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #2: (pci_remove_rescan_mutex){--..}, at: [<ffffffff803c10d1>] remove_callback+0x21/0x40 stack backtrace: Pid: 56, comm: events/4 Not tainted 2.6.29-rc8-kk #1 Call Trace: [<ffffffff8026dfcd>] validate_chain+0xb7d/0x1260 [<ffffffff8026eade>] __lock_acquire+0x42e/0xa40 [<ffffffff8026f148>] lock_acquire+0x58/0x80 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff8025800d>] flush_workqueue+0x4d/0xa0 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff80258070>] flush_scheduled_work+0x10/0x20 [<ffffffffa0144065>] e1000_remove+0x55/0xfe [e1000e] [<ffffffff8033ee30>] ? sysfs_schedule_callback_work+0x0/0x50 [<ffffffff803bfeb2>] pci_device_remove+0x32/0x70 [<ffffffff80441da9>] __device_release_driver+0x59/0x90 [<ffffffff80441edb>] device_release_driver+0x2b/0x40 [<ffffffff804419d6>] bus_remove_device+0xa6/0x120 [<ffffffff8043e46b>] device_del+0x12b/0x190 [<ffffffff8043e4f6>] device_unregister+0x26/0x70 [<ffffffff803ba969>] pci_stop_dev+0x49/0x60 [<ffffffff803baab0>] pci_remove_bus_device+0x40/0xc0 [<ffffffff803c10d9>] remove_callback+0x29/0x40 [<ffffffff8033ee4f>] sysfs_schedule_callback_work+0x1f/0x50 [<ffffffff8025769a>] run_workqueue+0x15a/0x230 [<ffffffff80257648>] ? run_workqueue+0x108/0x230 [<ffffffff8025846f>] worker_thread+0x9f/0x100 [<ffffffff8025bce0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff802583d0>] ? worker_thread+0x0/0x100 [<ffffffff8025b89d>] kthread+0x4d/0x80 [<ffffffff8020d4ba>] child_rip+0xa/0x20 [<ffffffff8020cebc>] ? restore_args+0x0/0x30 [<ffffffff8025b850>] ? kthread+0x0/0x80 [<ffffffff8020d4b0>] ? child_rip+0x0/0x20 Although we know that the device_unregister path will never acquire a lock that a driver might try to acquire in its ->remove, in general we should never attempt to flush a workqueue from within the same workqueue, and lockdep rightly complains. So as long as sysfs attributes cannot commit suicide directly and we are stuck with this callback mechanism, put the sysfs callbacks on their own workqueue instead of the global one. This has the side benefit that if a suicidal sysfs attribute kicks off a long chain of ->remove callbacks, we no longer induce a long delay on the global queue. This also fixes a missing module_put in the error path introduced by sysfs-only-allow-one-scheduled-removal-callback-per-kobj.patch. We never destroy the workqueue, but I'm not sure that's a problem. Reported-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Tested-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Signed-off-by: Alex Chiang <achiang@hp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-03-26 05:11:36 +08:00
if (sysfs_workqueue == NULL) {
module_put(owner);
return -ENOMEM;
}
}
ss = kmalloc(sizeof(*ss), GFP_KERNEL);
if (!ss) {
module_put(owner);
return -ENOMEM;
}
kobject_get(kobj);
ss->kobj = kobj;
ss->func = func;
ss->data = data;
ss->owner = owner;
INIT_WORK(&ss->work, sysfs_schedule_callback_work);
INIT_LIST_HEAD(&ss->workq_list);
mutex_lock(&sysfs_workq_mutex);
list_add_tail(&ss->workq_list, &sysfs_workq);
mutex_unlock(&sysfs_workq_mutex);
sysfs: don't use global workqueue in sysfs_schedule_callback() A sysfs attribute using sysfs_schedule_callback() to commit suicide may end up calling device_unregister(), which will eventually call a driver's ->remove function. Drivers may call flush_scheduled_work() in their shutdown routines, in which case lockdep will complain with something like the following: ============================================= [ INFO: possible recursive locking detected ] 2.6.29-rc8-kk #1 --------------------------------------------- events/4/56 is trying to acquire lock: (events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0 but task is already holding lock: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 other info that might help us debug this: 3 locks held by events/4/56: #0: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #1: (&ss->work){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230 #2: (pci_remove_rescan_mutex){--..}, at: [<ffffffff803c10d1>] remove_callback+0x21/0x40 stack backtrace: Pid: 56, comm: events/4 Not tainted 2.6.29-rc8-kk #1 Call Trace: [<ffffffff8026dfcd>] validate_chain+0xb7d/0x1260 [<ffffffff8026eade>] __lock_acquire+0x42e/0xa40 [<ffffffff8026f148>] lock_acquire+0x58/0x80 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff8025800d>] flush_workqueue+0x4d/0xa0 [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0 [<ffffffff80258070>] flush_scheduled_work+0x10/0x20 [<ffffffffa0144065>] e1000_remove+0x55/0xfe [e1000e] [<ffffffff8033ee30>] ? sysfs_schedule_callback_work+0x0/0x50 [<ffffffff803bfeb2>] pci_device_remove+0x32/0x70 [<ffffffff80441da9>] __device_release_driver+0x59/0x90 [<ffffffff80441edb>] device_release_driver+0x2b/0x40 [<ffffffff804419d6>] bus_remove_device+0xa6/0x120 [<ffffffff8043e46b>] device_del+0x12b/0x190 [<ffffffff8043e4f6>] device_unregister+0x26/0x70 [<ffffffff803ba969>] pci_stop_dev+0x49/0x60 [<ffffffff803baab0>] pci_remove_bus_device+0x40/0xc0 [<ffffffff803c10d9>] remove_callback+0x29/0x40 [<ffffffff8033ee4f>] sysfs_schedule_callback_work+0x1f/0x50 [<ffffffff8025769a>] run_workqueue+0x15a/0x230 [<ffffffff80257648>] ? run_workqueue+0x108/0x230 [<ffffffff8025846f>] worker_thread+0x9f/0x100 [<ffffffff8025bce0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff802583d0>] ? worker_thread+0x0/0x100 [<ffffffff8025b89d>] kthread+0x4d/0x80 [<ffffffff8020d4ba>] child_rip+0xa/0x20 [<ffffffff8020cebc>] ? restore_args+0x0/0x30 [<ffffffff8025b850>] ? kthread+0x0/0x80 [<ffffffff8020d4b0>] ? child_rip+0x0/0x20 Although we know that the device_unregister path will never acquire a lock that a driver might try to acquire in its ->remove, in general we should never attempt to flush a workqueue from within the same workqueue, and lockdep rightly complains. So as long as sysfs attributes cannot commit suicide directly and we are stuck with this callback mechanism, put the sysfs callbacks on their own workqueue instead of the global one. This has the side benefit that if a suicidal sysfs attribute kicks off a long chain of ->remove callbacks, we no longer induce a long delay on the global queue. This also fixes a missing module_put in the error path introduced by sysfs-only-allow-one-scheduled-removal-callback-per-kobj.patch. We never destroy the workqueue, but I'm not sure that's a problem. Reported-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Tested-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Signed-off-by: Alex Chiang <achiang@hp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-03-26 05:11:36 +08:00
queue_work(sysfs_workqueue, &ss->work);
return 0;
}
EXPORT_SYMBOL_GPL(sysfs_schedule_callback);