From 77e443ab294ca5b88896e8ddab41884948d5519a Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Wed, 7 Dec 2022 03:53:33 +0000 Subject: [PATCH] io_uring: never run tw and fallback in parallel Once we fallback a tw we want all requests to that task to be given to the fallback wq so we dont run it in parallel with the last, i.e. post PF_EXITING, tw run of the task. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/96f4987265c4312f376f206511c6af3e77aaf5ac.1670384893.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- io_uring/io_uring.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index a29cbf973287..310cdd864a6c 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -149,6 +149,7 @@ static void io_clean_op(struct io_kiocb *req); static void io_queue_sqe(struct io_kiocb *req); static void io_move_task_work_from_local(struct io_ring_ctx *ctx); static void __io_submit_flush_completions(struct io_ring_ctx *ctx); +static __cold void io_fallback_tw(struct io_uring_task *tctx); static struct kmem_cache *req_cachep; @@ -1149,10 +1150,17 @@ void tctx_task_work(struct callback_head *cb) struct io_uring_task *tctx = container_of(cb, struct io_uring_task, task_work); struct llist_node fake = {}; - struct llist_node *node = io_llist_xchg(&tctx->task_list, &fake); + struct llist_node *node; unsigned int loops = 1; - unsigned int count = handle_tw_list(node, &ctx, &uring_locked, NULL); + unsigned int count; + if (unlikely(current->flags & PF_EXITING)) { + io_fallback_tw(tctx); + return; + } + + node = io_llist_xchg(&tctx->task_list, &fake); + count = handle_tw_list(node, &ctx, &uring_locked, NULL); node = io_llist_cmpxchg(&tctx->task_list, &fake, NULL); while (node != &fake) { loops++;