[PATCH 6.6 390/583] io_uring: ensure local task_work is run on wait timeout

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6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jens Axboe <axboe@xxxxxxxxx>

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@xxxxxxxxxxxxxxx
Fixes: 846072f16eed ("io_uring: mimimise io_cqring_wait_schedule")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 io_uring/io_uring.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2630,8 +2630,6 @@ static int io_cqring_wait(struct io_ring
 		__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
 		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 */






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