io_uring: fix lack of protection for compl_nr
coml_nr in ctx_flush_and_put() is not protected by uring_lock, this may cause problems when accessing in parallel: say coml_nr > 0 ctx_flush_and put other context if (compl_nr) get mutex coml_nr > 0 do flush coml_nr = 0 release mutex get mutex do flush (*) release mutex in (*) place, we call io_cqring_ev_posted() and users likely get no events there. To avoid spurious events, re-check the value when under the lock. Fixes: 2c32395d ("io_uring: fix __tctx_task_work() ctx race") Signed-off-by:Hao Xu <haoxu@linux.alibaba.com> Link: https://lore.kernel.org/r/20210820221954.61815-1-haoxu@linux.alibaba.com Signed-off-by:
Jens Axboe <axboe@kernel.dk>
parent
187f08c1
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