On Wed, Jul 07, 2010 at 02:52:58PM +0200, Jiri Slaby wrote:
> Hi,
>
> stanse found a locking error in lirc_dev_fop_read:
> if (mutex_lock_interruptible(&ir->irctl_lock))
> return -ERESTARTSYS;
> ...
> while (written < length && ret == 0) {
> if (mutex_lock_interruptible(&ir->irctl_lock)) { #1
> ret = -ERESTARTSYS;
> break;
> }
> ...
> }
>
> remove_wait_queue(&ir->buf->wait_poll, &wait);
> set_current_state(TASK_RUNNING);
> mutex_unlock(&ir->irctl_lock); #2
>
> If lock at #1 fails, it beaks out of the loop, with the lock unlocked,
> but there is another "unlock" at #2.
This should do the trick. Completely untested beyond compiling, but its
not exactly a complicated fix, and in practice, I'm not aware of anyone
ever actually tripping that locking bug, so there's zero functional change
in typical use here.
Signed-off-by: Jarod Wilson <jarod@xxxxxxxxxx>
---
drivers/media/IR/lirc_dev.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/drivers/media/IR/lirc_dev.c b/drivers/media/IR/lirc_dev.c
index 9e141d5..64170fa 100644
--- a/drivers/media/IR/lirc_dev.c
+++ b/drivers/media/IR/lirc_dev.c
@@ -657,7 +657,9 @@ ssize_t lirc_dev_fop_read(struct file *file,
if (mutex_lock_interruptible(&ir->irctl_lock)) {
ret = -ERESTARTSYS;
- break;
+ remove_wait_queue(&ir->buf->wait_poll, &wait);
+ set_current_state(TASK_RUNNING);
+ goto out_unlocked;
}
if (!ir->attached) {
@@ -676,6 +678,7 @@ ssize_t lirc_dev_fop_read(struct file *file,
set_current_state(TASK_RUNNING);
mutex_unlock(&ir->irctl_lock);
+out_unlocked:
dev_dbg(ir->d.dev, LOGHEAD "read result = %s (%d)\n",
ir->d.name, ir->d.minor, ret ? "-EFAULT" : "OK", ret);
--
Jarod Wilson
jarod@xxxxxxxxxx
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