From: Jens Axboe Date: Thu, 4 Jan 2024 19:21:08 +0000 (-0700) Subject: io_uring: ensure local task_work is run on wait timeout X-Git-Tag: v6.6.17~977 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0241f4c2caad6f5ec50dc935eac7bdf7f4ee84d0;p=platform%2Fkernel%2Flinux-rpi.git io_uring: ensure local task_work is run on wait timeout commit 6ff1407e24e6fdfa4a16ba9ba551e3d253a26391 upstream. A previous commit added an earlier break condition here, which is fine if we're using non-local task_work as it'll be run on return to userspace. However, if DEFER_TASKRUN is used, then we could be leaving local task_work that is ready to process in the ctx list until next time that we enter the kernel to wait for events. Move the break condition to _after_ we have run task_work. Cc: stable@vger.kernel.org Fixes: 846072f16eed ("io_uring: mimimise io_cqring_wait_schedule") Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index b406cc6..1cc4c7b 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -2630,8 +2630,6 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, __set_current_state(TASK_RUNNING); atomic_set(&ctx->cq_wait_nr, 0); - if (ret < 0) - break; /* * Run task_work after scheduling and before io_should_wake(). * If we got woken because of task_work being processed, run it @@ -2641,6 +2639,18 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, if (!llist_empty(&ctx->work_llist)) io_run_local_work(ctx); + /* + * Non-local task_work will be run on exit to userspace, but + * if we're using DEFER_TASKRUN, then we could have waited + * with a timeout for a number of requests. If the timeout + * hits, we could have some requests ready to process. Ensure + * this break is _after_ we have run task_work, to avoid + * deferring running potentially pending requests until the + * next time we wait for events. + */ + if (ret < 0) + break; + check_cq = READ_ONCE(ctx->check_cq); if (unlikely(check_cq)) { /* let the caller flush overflows, retry */