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From: Xiaoguang Wang <[email protected]>
To: [email protected]
Cc: [email protected], [email protected]
Subject: [PATCH v3 3/3] io_uring: don't get completion_lock in io_poll_rewait()
Date: Mon, 25 Oct 2021 13:38:49 +0800	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

In current implementation, if there are not available events,
io_poll_rewait() just gets completion_lock, and unlocks it in
io_poll_task_func() or io_async_task_func(), which isn't necessary.

Change this logic to let io_poll_task_func() or io_async_task_func()
get the completion_lock lock.

Signed-off-by: Xiaoguang Wang <[email protected]>
---
 fs/io_uring.c | 58 ++++++++++++++++++++++++++--------------------------------
 1 file changed, 26 insertions(+), 32 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e4c779dac953..41ff8fdafe55 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5248,10 +5248,7 @@ static inline int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *pol
 }
 
 static bool io_poll_rewait(struct io_kiocb *req, struct io_poll_iocb *poll)
-	__acquires(&req->ctx->completion_lock)
 {
-	struct io_ring_ctx *ctx = req->ctx;
-
 	/* req->task == current here, checking PF_EXITING is safe */
 	if (unlikely(req->task->flags & PF_EXITING))
 		WRITE_ONCE(poll->canceled, true);
@@ -5262,7 +5259,6 @@ static bool io_poll_rewait(struct io_kiocb *req, struct io_poll_iocb *poll)
 		req->result = vfs_poll(req->file, &pt) & poll->events;
 	}
 
-	spin_lock(&ctx->completion_lock);
 	if (!req->result && !READ_ONCE(poll->canceled)) {
 		if (req->opcode == IORING_OP_POLL_ADD)
 			WRITE_ONCE(poll->active, true);
@@ -5357,35 +5353,34 @@ static void io_poll_task_func(struct io_kiocb *req, bool *locked)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	struct io_kiocb *nxt;
+	bool done;
 
-	if (io_poll_rewait(req, &req->poll)) {
-		spin_unlock(&ctx->completion_lock);
-	} else {
-		bool done;
+	if (io_poll_rewait(req, &req->poll))
+		return;
 
-		if (req->poll.done) {
-			spin_unlock(&ctx->completion_lock);
-			return;
-		}
-		done = __io_poll_complete(req, req->result);
-		if (done) {
-			io_poll_remove_double(req);
-			__io_poll_remove_one(req, io_poll_get_single(req), true);
-			hash_del(&req->hash_node);
-			req->poll.done = true;
-		} else {
-			req->result = 0;
-			WRITE_ONCE(req->poll.active, true);
-		}
-		io_commit_cqring(ctx);
+	spin_lock(&ctx->completion_lock);
+	if (req->poll.done) {
 		spin_unlock(&ctx->completion_lock);
-		io_cqring_ev_posted(ctx);
+		return;
+	}
+	done = __io_poll_complete(req, req->result);
+	if (done) {
+		io_poll_remove_double(req);
+		__io_poll_remove_one(req, io_poll_get_single(req), true);
+		hash_del(&req->hash_node);
+		req->poll.done = true;
+	} else {
+		req->result = 0;
+		WRITE_ONCE(req->poll.active, true);
+	}
+	io_commit_cqring(ctx);
+	spin_unlock(&ctx->completion_lock);
+	io_cqring_ev_posted(ctx);
 
-		if (done) {
-			nxt = io_put_req_find_next(req);
-			if (nxt)
-				io_req_task_submit(nxt, locked);
-		}
+	if (done) {
+		nxt = io_put_req_find_next(req);
+		if (nxt)
+			io_req_task_submit(nxt, locked);
 	}
 }
 
@@ -5507,11 +5502,10 @@ static void io_async_task_func(struct io_kiocb *req, bool *locked)
 
 	trace_io_uring_task_run(req->ctx, req, req->opcode, req->user_data);
 
-	if (io_poll_rewait(req, &apoll->poll)) {
-		spin_unlock(&ctx->completion_lock);
+	if (io_poll_rewait(req, &apoll->poll))
 		return;
-	}
 
+	spin_lock(&ctx->completion_lock);
 	hash_del(&req->hash_node);
 	io_poll_remove_double(req);
 	apoll->poll.done = true;
-- 
2.14.4.44.g2045bb6


  parent reply	other threads:[~2021-10-25  5:38 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-25  5:38 [PATCH v3 0/3] improvements for multi-shot poll requests Xiaoguang Wang
2021-10-25  5:38 ` [PATCH v3 1/3] io_uring: refactor event check out of __io_async_wake() Xiaoguang Wang
2021-10-25  9:35   ` Praveen Kumar
2021-10-25  5:38 ` [PATCH v3 2/3] io_uring: reduce frequent add_wait_queue() overhead for multi-shot poll request Xiaoguang Wang
2021-10-28 19:21   ` Pavel Begunkov
2021-10-29  2:57     ` Xiaoguang Wang
2021-10-29 10:02       ` Pavel Begunkov
2021-10-29 13:37         ` Xiaoguang Wang
2021-10-29 13:47           ` Pavel Begunkov
2021-10-29 14:12           ` Pavel Begunkov
2021-10-29 14:34             ` Xiaoguang Wang
2021-10-25  5:38 ` Xiaoguang Wang [this message]
2021-10-28 19:26   ` [PATCH v3 3/3] io_uring: don't get completion_lock in io_poll_rewait() Pavel Begunkov
2021-10-29  5:59     ` Xiaoguang Wang
2021-10-28 18:19 ` [PATCH v3 0/3] improvements for multi-shot poll requests Jens Axboe
2021-10-29 18:29   ` Jens Axboe
2021-10-28 18:19 ` Jens Axboe
2021-10-28 19:01   ` Pavel Begunkov
2021-10-28 19:04     ` Pavel Begunkov

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