[PATCH 2/4] io_uring: add local task_work run helper that is entered locked

[Jens Axboe <axboe@xxxxxxxxx>]

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@xxxxxxxxx>
---
 io_uring/io_uring.c | 23 ++++++++++++++++-------
 io_uring/io_uring.h |  1 +
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 4edc31d0a3e0..f841f0e126bc 100644
--- a/io_uring/io_uring.c
+++ b/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)
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index f417d75d7bc1..0f90d1dfa42b 100644
--- a/io_uring/io_uring.h
+++ b/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);
-- 
2.35.1