io_uring: remove extra sqpoll submission halting

commit 3b763ba1c77da5806e4fdc5684285814fe970c98 upstream.

SQPOLL task won't submit requests for a context that is currently dying,
so no need to remove ctx from sqd_list prior the main loop of
io_ring_exit_work(). Kill it, will be removed by io_sq_thread_finish()
and only brings confusion and lockups.

Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f220c2b786ba0f9499bebc9f3cd9714d29efb6a5.1618752958.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0bc4727e8a9068fd4e59b85e114d54cb84dde12d..b693c5dc6dec266e8c58d9d98d6cc581a7cae8c2 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6710,6 +6710,10 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
                if (!list_empty(&ctx->iopoll_list))
                        io_do_iopoll(ctx, &nr_events, 0);
 
+               /*
+                * Don't submit if refs are dying, good for io_uring_register(),
+                * but also it is relied upon by io_ring_exit_work()
+                */
                if (to_submit && likely(!percpu_ref_is_dying(&ctx->refs)) &&
                    !(ctx->flags & IORING_SETUP_R_DISABLED))
                        ret = io_submit_sqes(ctx, to_submit);
@@ -8576,14 +8580,6 @@ static void io_ring_exit_work(struct work_struct *work)
        struct io_tctx_node *node;
        int ret;
 
-       /* prevent SQPOLL from submitting new requests */
-       if (ctx->sq_data) {
-               io_sq_thread_park(ctx->sq_data);
-               list_del_init(&ctx->sqd_list);
-               io_sqd_update_thread_idle(ctx->sq_data);
-               io_sq_thread_unpark(ctx->sq_data);
-       }
-
        /*
         * If we're doing polled IO and end up having requests being
         * submitted async (out-of-line), then completions can come in while