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uio: change to use the mutex lock instead of the spin lock 

We are hitting a regression with the following commit:

commit a93e7b3315
Author: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Date:   Mon May 14 13:32:23 2018 +1200

    uio: Prevent device destruction while fds are open

The problem is the addition of spin_lock_irqsave in uio_write. This
leads to hitting  uio_write -> copy_from_user -> _copy_from_user ->
might_fault and the logs filling up with sleeping warnings.

I also noticed some uio drivers allocate memory, sleep, grab mutexes
from callouts like open() and release and uio is now doing
spin_lock_irqsave while calling them.

Reported-by: Mike Christie <mchristi@redhat.com>
CC: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Reviewed-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiubo Li 2018-07-06 22:05:38 -04:00 committed by Greg Kroah-Hartman
parent 9421e45f5f
commit 543af5861f
2 changed files with 14 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/uio/uio.c
View File

@ -433,7 +433,6 @@ static int uio_open(struct inode *inode, struct file *filep)
struct uio_device *idev;
struct uio_listener *listener;
int ret = 0;
unsigned long flags;
mutex_lock(&minor_lock);
idev = idr_find(&uio_idr, iminor(inode));
@ -460,10 +459,10 @@ static int uio_open(struct inode *inode, struct file *filep)
listener->event_count = atomic_read(&idev->event);
filep->private_data = listener;
spin_lock_irqsave(&idev->info_lock, flags);
mutex_lock(&idev->info_lock);
if (idev->info && idev->info->open)
ret = idev->info->open(idev->info, inode);
spin_unlock_irqrestore(&idev->info_lock, flags);
mutex_unlock(&idev->info_lock);
if (ret)
goto err_infoopen;
@ -495,12 +494,11 @@ static int uio_release(struct inode *inode, struct file *filep)
int ret = 0;
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
unsigned long flags;
spin_lock_irqsave(&idev->info_lock, flags);
mutex_lock(&idev->info_lock);
if (idev->info && idev->info->release)
ret = idev->info->release(idev->info, inode);
spin_unlock_irqrestore(&idev->info_lock, flags);
mutex_unlock(&idev->info_lock);
module_put(idev->owner);
kfree(listener);
@ -513,12 +511,11 @@ static __poll_t uio_poll(struct file *filep, poll_table *wait)
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
__poll_t ret = 0;
unsigned long flags;
spin_lock_irqsave(&idev->info_lock, flags);
mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq)
ret = -EIO;
spin_unlock_irqrestore(&idev->info_lock, flags);
mutex_unlock(&idev->info_lock);
if (ret)
return ret;
@ -537,12 +534,11 @@ static ssize_t uio_read(struct file *filep, char __user *buf,
DECLARE_WAITQUEUE(wait, current);
ssize_t retval = 0;
s32 event_count;
unsigned long flags;
spin_lock_irqsave(&idev->info_lock, flags);
mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq)
retval = -EIO;
spin_unlock_irqrestore(&idev->info_lock, flags);
mutex_unlock(&idev->info_lock);
if (retval)
return retval;
@ -592,9 +588,8 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
struct uio_device *idev = listener->dev;
ssize_t retval;
s32 irq_on;
unsigned long flags;
spin_lock_irqsave(&idev->info_lock, flags);
mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq) {
retval = -EIO;
goto out;
@ -618,7 +613,7 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
retval = idev->info->irqcontrol(idev->info, irq_on);
out:
spin_unlock_irqrestore(&idev->info_lock, flags);
mutex_unlock(&idev->info_lock);
return retval ? retval : sizeof(s32);
}
@ -865,7 +860,7 @@ int __uio_register_device(struct module *owner,
idev->owner = owner;
idev->info = info;
spin_lock_init(&idev->info_lock);
mutex_init(&idev->info_lock);
init_waitqueue_head(&idev->wait);
atomic_set(&idev->event, 0);
@ -929,7 +924,6 @@ EXPORT_SYMBOL_GPL(__uio_register_device);
void uio_unregister_device(struct uio_info *info)
{
struct uio_device *idev;
unsigned long flags;
if (!info || !info->uio_dev)
return;
@ -943,9 +937,9 @@ void uio_unregister_device(struct uio_info *info)
if (info->irq && info->irq != UIO_IRQ_CUSTOM)
free_irq(info->irq, idev);
spin_lock_irqsave(&idev->info_lock, flags);
mutex_lock(&idev->info_lock);
idev->info = NULL;
spin_unlock_irqrestore(&idev->info_lock, flags);
mutex_unlock(&idev->info_lock);
device_unregister(&idev->dev);

2
include/linux/uio_driver.h
View File

@ -75,7 +75,7 @@ struct uio_device {
struct fasync_struct *async_queue;
wait_queue_head_t wait;
struct uio_info *info;
spinlock_t info_lock;
struct mutex info_lock;
struct kobject *map_dir;
struct kobject *portio_dir;
};