io_uring: hold uring_lock across io_kill_timeouts() in cancel path

io_uring_try_cancel_requests() dropped ctx->uring_lock before calling
io_kill_timeouts(), which walks each timeout's link chain via
io_match_task() to test REQ_F_INFLIGHT. With chain mutation now
serialized by ctx->uring_lock, that walk needs the lock too.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: axboe

io_uring/cancel.c

@@ -561,8 +561,8 @@ __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
 	ret |= io_waitid_remove_all(ctx, tctx, cancel_all);
 	ret |= io_futex_remove_all(ctx, tctx, cancel_all);
 	ret |= io_uring_try_cancel_uring_cmd(ctx, tctx, cancel_all);
-	mutex_unlock(&ctx->uring_lock);
 	ret |= io_kill_timeouts(ctx, tctx, cancel_all);
+	mutex_unlock(&ctx->uring_lock);
 	if (tctx)
 		ret |= io_run_task_work() > 0;
 	else