io_uring: add local task_work run helper that is entered locked

We have a few spots that drop the mutex just to run local task_work,
which immediately tries to grab it again. Add a helper that just passes
in whether we're locked already.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -1161,9 +1161,8 @@ static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx)
 	}
 }
 
-int io_run_local_work(struct io_ring_ctx *ctx)
+int __io_run_local_work(struct io_ring_ctx *ctx, bool locked)
 {
-	bool locked;
 	struct llist_node *node;
 	struct llist_node fake;
 	struct llist_node *current_final = NULL;
@@ -1178,8 +1177,6 @@ int io_run_local_work(struct io_ring_ctx *ctx)
 		return -EEXIST;
 	}
 
-	locked = mutex_trylock(&ctx->uring_lock);
-
 	node = io_llist_xchg(&ctx->work_llist, &fake);
 	ret = 0;
 again:
@@ -1204,12 +1201,24 @@ int io_run_local_work(struct io_ring_ctx *ctx)
 		goto again;
 	}
 
-	if (locked) {
+	if (locked)
 		io_submit_flush_completions(ctx);
-		mutex_unlock(&ctx->uring_lock);
-	}
 	trace_io_uring_local_work_run(ctx, ret, loops);
 	return ret;
+
+}
+
+int io_run_local_work(struct io_ring_ctx *ctx)
+{
+	bool locked;
+	int ret;
+
+	locked = mutex_trylock(&ctx->uring_lock);
+	ret = __io_run_local_work(ctx, locked);
+	if (locked)
+		mutex_unlock(&ctx->uring_lock);
+
+	return ret;
 }
 
 static void io_req_tw_post(struct io_kiocb *req, bool *locked)

io_uring/io_uring.h

@@ -27,6 +27,7 @@ enum {
 struct io_uring_cqe *__io_get_cqe(struct io_ring_ctx *ctx);
 bool io_req_cqe_overflow(struct io_kiocb *req);
 int io_run_task_work_sig(struct io_ring_ctx *ctx);
+int __io_run_local_work(struct io_ring_ctx *ctx, bool locked);
 int io_run_local_work(struct io_ring_ctx *ctx);
 void io_req_complete_failed(struct io_kiocb *req, s32 res);
 void __io_req_complete(struct io_kiocb *req, unsigned issue_flags);