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author | Johannes Berg <johannes.berg@intel.com> | 2018-08-22 11:49:04 +0200 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2018-08-22 08:31:38 -0700 |
commit | 87915adc3f0acdf03c776df42e308e5a155c19af (patch) | |
tree | cce568b654b2bb6e7d893655c9693b370dcd98bd /kernel/workqueue.c | |
parent | d6e89786bed977f37f55ffca11e563f6d2b1e3b5 (diff) | |
download | linux-stable-87915adc3f0acdf03c776df42e308e5a155c19af.tar.gz linux-stable-87915adc3f0acdf03c776df42e308e5a155c19af.tar.bz2 linux-stable-87915adc3f0acdf03c776df42e308e5a155c19af.zip |
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: fd1a5b04dfb8 ("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>
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r-- | kernel/workqueue.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index aa520e715bbc..661184fcd503 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2652,6 +2652,9 @@ void flush_workqueue(struct workqueue_struct *wq) if (WARN_ON(!wq_online)) return; + lock_map_acquire(&wq->lockdep_map); + lock_map_release(&wq->lockdep_map); + mutex_lock(&wq->mutex); /* @@ -2905,6 +2908,11 @@ static bool __flush_work(struct work_struct *work, bool from_cancel) if (WARN_ON(!wq_online)) return false; + if (!from_cancel) { + lock_map_acquire(&work->lockdep_map); + lock_map_release(&work->lockdep_map); + } + if (start_flush_work(work, &barr, from_cancel)) { wait_for_completion(&barr.done); destroy_work_on_stack(&barr.work); |