From bd99c71bd14072ce2920f6d0c2fe43df072c653c Mon Sep 17 00:00:00 2001 From: Hao Xu Date: Wed, 22 Sep 2021 18:12:36 +0800 Subject: 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: 5082620fb2ca ("io_uring: terminate multishot poll for CQ ring overflow") Signed-off-by: Hao Xu Link: https://lore.kernel.org/r/20210922101238.7177-2-haoxu@linux.alibaba.com Signed-off-by: Jens Axboe --- fs/io_uring.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index e372d5b9f6dc..43530aae6180 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5337,10 +5337,8 @@ static bool __io_poll_complete(struct io_kiocb *req, __poll_t mask) } if (req->poll.events & EPOLLONESHOT) flags = 0; - if (!io_cqring_fill_event(ctx, req->user_data, error, flags)) { - req->poll.done = true; + if (!io_cqring_fill_event(ctx, req->user_data, error, flags)) flags = 0; - } if (flags & IORING_CQE_F_MORE) ctx->cq_extra++; @@ -5371,6 +5369,7 @@ static void io_poll_task_func(struct io_kiocb *req, bool *locked) if (done) { io_poll_remove_double(req); hash_del(&req->hash_node); + req->poll.done = true; } else { req->result = 0; add_wait_queue(req->poll.head, &req->poll.wait); @@ -5508,6 +5507,7 @@ static void io_async_task_func(struct io_kiocb *req, bool *locked) hash_del(&req->hash_node); io_poll_remove_double(req); + apoll->poll.done = true; spin_unlock(&ctx->completion_lock); if (!READ_ONCE(apoll->poll.canceled)) -- cgit v1.2.3