io-wq: fix potential race of acct->nr_workers

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Given max_worker is 1, and we currently have 1 running and it is
exiting. There may be race like:
 io_wqe_enqueue                   worker1
                               no work there and timeout
                               unlock(wqe->lock)
 ->insert work
                               -->io_worker_exit
 lock(wqe->lock)
 ->if(!nr_workers) //it's still 1
 unlock(wqe->lock)
    goto run_cancel
                                  lock(wqe->lock)
                                  nr_workers--
                                  ->dec_running
                                    ->worker creation fails
                                  unlock(wqe->lock)

We enqueued one work but there is no workers, causes hung.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

...

This commit is contained in:

Hao Xu 2021-09-12 03:40:52 +08:00 • committed by Jens Axboe

parent 7a842fb589

commit 767a65e9f3

1 changed files with 1 additions and 2 deletions

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fs/io-wq.c

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