workqueue: re-add lockdep dependencies for flushing
In flush_work(), we need to create a lockdep dependency so that the following scenario is appropriately tagged as a problem: work_function() { mutex_lock(&mutex); ... } other_function() { mutex_lock(&mutex); flush_work(&work); // or cancel_work_sync(&work); } This is a problem since the work might be running and be blocked on trying to acquire the mutex. Similarly, in flush_workqueue(). These were removed after cross-release partially caught these problems, but now cross-release was reverted anyway. IMHO the removal was erroneous anyway though, since lockdep should be able to catch potential problems, not just actual ones, and cross-release would only have caught the problem when actually invoking wait_for_completion(). Fixes: fd1a5b04 ("workqueue: Remove now redundant lock acquisitions wrt. workqueue flushes") Signed-off-by:Johannes Berg <johannes.berg@intel.com> Signed-off-by:
Tejun Heo <tj@kernel.org>
parent
d6e89786