tree 744a387ea6c9555b197842db8e87cd538ddfc958
parent 4fa11ec726a32ea6dd768dbb2e2af3453a98ec0a
author Johannes Berg <johannes.berg@intel.com> 1453804143 +0100
committer Johannes Berg <johannes.berg@intel.com> 1453804325 +0100

rfkill: fix rfkill_fop_read wait_event usage

The code within wait_event_interruptible() is called with
!TASK_RUNNING, so mustn't call any functions that can sleep,
like mutex_lock().

Since we re-check the list_empty() in a loop after the wait,
it's safe to simply use list_empty() without locking.

This bug has existed forever, but was only discovered now
because all userspace implementations, including the default
'rfkill' tool, use poll() or select() to get a readable fd
before attempting to read.

Cc: stable@vger.kernel.org
Fixes: c64fb01627e24 ("rfkill: create useful userspace interface")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>