io_uring: fix race between poll completion and cancel_hash insertion
If poll arming and poll completion runs in parallel, there maybe races. For instance, run io_poll_add in iowq and io_poll_task_func in original context, then: iowq original context io_poll_add vfs_poll (interruption happens tw queued to original context) io_poll_task_func generate cqe del from cancel_hash[] if !poll.done insert to cancel_hash[] The entry left in cancel_hash[], similar case for fast poll. Fix it by set poll.done = true when del from cancel_hash[]. Fixes: 5082620f ("io_uring: terminate multishot poll for CQ ring overflow") Signed-off-by:Hao Xu <haoxu@linux.alibaba.com> Link: https://lore.kernel.org/r/20210922101238.7177-2-haoxu@linux.alibaba.com Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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87c16966