linux-kernel - [PATCH v2 3/8] io_uring: refactor __io_cq_unlock_post

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Message-Id: <662ee5d898168ac206be06038525e97b64072a46.1680782017.git.asml.silence@gmail.com>
Date:   Thu,  6 Apr 2023 14:20:09 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     io-uring@...r.kernel.org
Cc:     Jens Axboe <axboe@...nel.dk>, asml.silence@...il.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/8] io_uring: refactor __io_cq_unlock_post_flush()

Instead of smp_mb() + __io_cqring_wake() in __io_cq_unlock_post_flush()
use equivalent io_cqring_wake(). With that we can clean it up further
and remove __io_cqring_wake().

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 io_uring/io_uring.c |  6 ++----
 io_uring/io_uring.h | 11 ++---------
 2 files changed, 4 insertions(+), 13 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index fb7215b543cd..d4ac62de2113 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -640,10 +640,8 @@ static inline void __io_cq_unlock_post_flush(struct io_ring_ctx *ctx)
 	 * it will re-check the wakeup conditions once we return we can safely
 	 * skip waking it up.
 	 */
-	if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN)) {
-		smp_mb();
-		__io_cqring_wake(ctx);
-	}
+	if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
+		io_cqring_wake(ctx);
 }
 
 void io_cq_unlock_post(struct io_ring_ctx *ctx)
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index 193b2db39fe8..24d8196bbca3 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -228,8 +228,7 @@ static inline void io_poll_wq_wake(struct io_ring_ctx *ctx)
 				poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
 }
 
-/* requires smb_mb() prior, see wq_has_sleeper() */
-static inline void __io_cqring_wake(struct io_ring_ctx *ctx)
+static inline void io_cqring_wake(struct io_ring_ctx *ctx)
 {
 	/*
 	 * Trigger waitqueue handler on all waiters on our waitqueue. This
@@ -241,17 +240,11 @@ static inline void __io_cqring_wake(struct io_ring_ctx *ctx)
 	 * waitqueue handlers, we know we have a dependency between eventfd or
 	 * epoll and should terminate multishot poll at that point.
 	 */
-	if (waitqueue_active(&ctx->cq_wait))
+	if (wq_has_sleeper(&ctx->cq_wait))
 		__wake_up(&ctx->cq_wait, TASK_NORMAL, 0,
 				poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
 }
 
-static inline void io_cqring_wake(struct io_ring_ctx *ctx)
-{
-	smp_mb();
-	__io_cqring_wake(ctx);
-}
-
 static inline bool io_sqring_full(struct io_ring_ctx *ctx)
 {
 	struct io_rings *r = ctx->rings;
-- 
2.40.0