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Tejun Heo 0ab66088c8 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>
 		2007-07-11 16:09:05 -07:00
..
9p Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
adfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
affs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
afs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
autofs Replace pid_t in autofs with struct pid reference 2007-05-11 08:29:36 -07:00
autofs4 Fix some coding-style errors in autofs 2007-05-11 08:29:36 -07:00
befs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
bfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
cifs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
coda sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
configfs Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
cramfs mm: make read_cache_page synchronous 2007-05-07 12:12:51 -07:00
debugfs debugfs: add rename for debugfs files 2007-07-11 16:09:00 -07:00
devpts devpts: add fsnotify create event 2007-05-08 11:14:59 -07:00
dlm [DLM] dump more lock values 2007-07-09 08:24:13 +01:00
ecryptfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
efs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
exportfs header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
ext2 xip sendfile removal 2007-07-10 08:04:15 +02:00
ext3 sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
ext4 sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
fat sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
freevxfs freevxfs: possible null pointer dereference fix 2007-05-08 11:14:59 -07:00
fuse sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
gfs2 Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw 2007-07-10 13:56:13 -07:00
hfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
hfsplus sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
hostfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
hpfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
hppfs [PATCH] Mark struct super_operations const 2007-02-12 09:48:47 -08:00
hugetlbfs shm: fix the filename of hugetlb sysv shared memory 2007-06-16 13:16:16 -07:00
isofs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
jbd fix file specification in comments 2007-05-09 08:58:16 +02:00
jbd2 fix file specification in comments 2007-05-09 08:58:16 +02:00
jffs2 sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
jfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
lockd NLM: Fix sparse warnings 2007-05-14 19:33:46 -04:00
minix sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
msdos [PATCH] mark struct inode_operations const 2 2007-02-12 09:48:46 -08:00
ncpfs Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
nfs sendfile: convert nfs to using splice_read() 2007-07-10 08:04:14 +02:00
nfs_common
…
nfsd pipe: change the ->pin() operation to ->confirm() 2007-07-10 08:04:15 +02:00
nls [PATCH] fs: make nls_cp936.c handle some U00XY characters and U20AC correctly 2006-12-07 08:39:46 -08:00
ntfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
ocfs2 pipe: change the ->pin() operation to ->confirm() 2007-07-10 08:04:15 +02:00
openpromfs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
partitions [S390] fixed cdl-format detection. 2007-07-10 11:24:44 +02:00
proc sched: scheduler debugging, core 2007-07-09 18:52:00 +02:00
qnx4 sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
ramfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
reiserfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
romfs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
smbfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
sysfs sysfs: implement sysfs_dirent active reference and immediate disconnect 2007-07-11 16:09:05 -07:00
sysv sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
udf sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
ufs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
vfat [PATCH] mark struct inode_operations const 3 2007-02-12 09:48:46 -08:00
xfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
Kconfig Remove obsolete fat_cvf help text 2007-05-09 08:58:15 +02:00
Kconfig.binfmt fs: Kill sh dependency for binfmt_flat. 2007-05-21 14:34:00 +09:00
Makefile signal/timer/event: eventfd core 2007-05-11 08:29:36 -07:00
aio.c signal/timer/event: KAIO eventfd support example 2007-05-11 08:29:37 -07:00
anon_inodes.c signal/timer/event fds: anonymous inode source 2007-05-11 08:29:36 -07:00
attr.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
bad_inode.c sendfile: remove bad_sendfile() from bad_file_ops 2007-07-10 08:04:15 +02:00
binfmt_aout.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
binfmt_elf.c Fix elf_core_dump() when writing arch specific notes (spu coredumps) 2007-07-06 10:23:43 -07:00
binfmt_elf_fdpic.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
binfmt_em86.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
binfmt_flat.c nommu: report correct errno in message 2007-06-08 17:23:32 -07:00
binfmt_misc.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
binfmt_script.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
binfmt_som.c
…
bio.c unexport bio_{,un}map_user 2007-07-10 08:03:34 +02:00
block_dev.c sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
buffer.c Fix "fs: convert core functions to zero_user_page" 2007-05-21 09:15:32 -07:00
char_dev.c [PATCH] remove protection of LANANA-reserved majors 2007-04-04 21:12:47 -07:00
compat.c optimize compat_core_sys_select() by a using stack space for small fd sets 2007-05-23 20:14:12 -07:00
compat_ioctl.c fix compat console unimap regression 2007-05-25 17:37:46 -07:00
dcache.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
dcookies.c [PATCH] slab: remove kmem_cache_t 2006-12-07 08:39:25 -08:00
direct-io.c dio: remove bogus refcounting BUG_ON 2007-07-03 18:23:23 -07:00
dnotify.c [PATCH] VFS: change struct file to use struct path 2006-12-08 08:28:41 -08:00
dquot.c circular locking dependency found in QUOTA OFF 2007-05-17 05:23:05 -07:00
drop_caches.c [PATCH] remove invalidate_inode_pages() 2007-02-11 10:51:31 -08:00
eventfd.c eventfd use waitqueue lock ... 2007-05-18 13:09:34 -07:00
eventpoll.c epoll: move kfree inside ep_free 2007-05-15 08:54:00 -07:00
exec.c uselib: add missing MNT_NOEXEC check 2007-05-23 20:14:13 -07:00
fcntl.c [PATCH] fdtable: Make fdarray and fdsets equal in size 2006-12-10 09:57:22 -08:00
fifo.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
file.c [PATCH] fdtable: Provide free_fdtable() wrapper 2006-12-22 08:55:50 -08:00
file_table.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
filesystems.c add filesystem subtype support 2007-05-08 11:15:01 -07:00
fs-writeback.c Write back inode data pages even when the inode itself is locked 2007-01-26 12:53:20 -08:00
generic_acl.c
…
inode.c Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
inotify.c Introduce a handy list_first_entry macro 2007-05-08 11:15:11 -07:00
inotify_user.c [PATCH] inotify: read return val fix 2007-02-12 09:48:28 -08:00
internal.h cleanup compat ioctl handling 2007-05-08 11:15:09 -07:00
ioctl.c vanishing ioctl handler debugging 2007-06-04 13:25:10 -07:00
ioprio.c [PATCH] pid: replace do/while_each_task_pid with do/while_each_pid_task 2007-02-12 09:48:32 -08:00
libfs.c fs/libfs.c: >80 columns line break fix 2007-05-09 06:44:57 +02:00
locks.c Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
mbcache.c [PATCH] slab: remove kmem_cache_t 2006-12-07 08:39:25 -08:00
mpage.c consolidate generic_writepages and mpage_writepages 2007-05-11 08:29:35 -07:00
namei.c [PATCH] complete message queue auditing 2007-05-11 05:38:26 -04:00
namespace.c check privileges before setting mount propagation 2007-05-08 11:15:12 -07:00
nfsctl.c
…
no-block.c
…
open.c Remove suid/sgid bits on [f]truncate() 2007-05-08 20:10:00 -07:00
pipe.c pipe: add documentation and comments 2007-07-10 08:04:16 +02:00
pnode.c Introduce a handy list_first_entry macro 2007-05-08 11:15:11 -07:00
pnode.h [PATCH] rename struct namespace to struct mnt_namespace 2006-12-08 08:28:51 -08:00
posix_acl.c
…
quota.c circular locking dependency found in QUOTA OFF 2007-05-17 05:23:05 -07:00
quota_v1.c
…
quota_v2.c
…
read_write.c Remove remnants of sendfile() 2007-07-10 08:04:15 +02:00
read_write.h
…
readdir.c ROUND_UP macro cleanup in fs/(select|compat|readdir).c 2007-05-08 11:15:09 -07:00
select.c Style fix in fs/select.c 2007-05-09 07:10:02 +02:00
seq_file.c Make common helpers for seq_files that work with list_heads 2007-07-10 17:51:13 -07:00
signalfd.c avoid spurious POLLIN returns in signalfd 2007-06-28 11:34:54 -07:00
splice.c pipe: add documentation and comments 2007-07-10 08:04:16 +02:00
stack.c [PATCH] fs/stack.c: Copy i_nlink after all other attributes are copied 2007-02-19 14:21:50 -08:00
stat.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
super.c add filesystem subtype support 2007-05-08 11:15:01 -07:00
sync.c Introduce fixed sys_sync_file_range2() syscall, implement on PowerPC and ARM 2007-06-28 11:38:30 -07:00
timerfd.c timerfd use waitqueue lock ... 2007-05-18 13:09:34 -07:00
utimes.c Fix permission checking for the new utimensat() system call 2007-07-08 12:02:55 -07:00
xattr.c [PATCH] audit inode for all xattr syscalls 2007-05-11 05:38:26 -04:00
xattr_acl.c [PATCH] remove many unneeded #includes of sched.h 2007-02-14 08:09:54 -08:00