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Subject: V4L/DVB: IR/lirc_dev: fix locking in lirc_dev_fop_read Author: Jarod Wilson <[email protected]> Date: Wed Jul 7 11:29:44 2010 -0300 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 <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]> drivers/media/IR/lirc_dev.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) --- http://git.linuxtv.org/v4l-dvb.git?a=commitdiff;h=cc3f0ab52ac470d3b268ffc10d632e72bf67e5d7 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); _______________________________________________ linuxtv-commits mailing list [email protected] http://www.linuxtv.org/cgi-bin/mailman/listinfo/linuxtv-commits
