io-wq: fix wakeup race when adding new work
When new work is added, io_wqe_enqueue() checks if we need to wake or create a new worker. But that check is done outside the lock that otherwise synchronizes us with a worker going to sleep, so we can end up in the following situation: CPU0 CPU1 lock insert work unlock atomic_read(nr_running) != 0 lock atomic_dec(nr_running) no wakeup needed Hold the wqe lock around the "need to wakeup" check. Then we can also get rid of the temporary work_flags variable, as we know the work will remain valid as long as we hold the lock. Cc: stable@vger.kernel.org Reported-by:Andres Freund <andres@anarazel.de> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
parent
a9a4aa9f
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