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From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org
Subject: [PATCH 04/23] io_uring: don't halt iopoll too early
Date: Thu, 29 Jul 2021 16:05:31 +0100	[thread overview]
Message-ID: <1374e437cb34e758d048d34f615b24be219b6faa.1627570633.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1627570633.git.asml.silence@gmail.com>

IOPOLL users should care more about getting completions for requests
they submitted, but not in "device did/completed something". Currently,
io_do_iopoll() may return a positive number, which will instruct
io_iopoll_check() to break the loop and end the syscall, even if there
is not enough CQEs or none at all.

Don't return positive numbers, so io_iopoll_check() exits only when it
gets an actual error, need reschedule or got enough CQEs.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6dca33fdb012..87d9a5d54464 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2276,7 +2276,6 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 	struct io_kiocb *req, *tmp;
 	LIST_HEAD(done);
 	bool spin;
-	int ret;
 
 	/*
 	 * Only spin for completions if we don't have multiple devices hanging
@@ -2284,9 +2283,9 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 	 */
 	spin = !ctx->poll_multi_queue && *nr_events < min;
 
-	ret = 0;
 	list_for_each_entry_safe(req, tmp, &ctx->iopoll_list, inflight_entry) {
 		struct kiocb *kiocb = &req->rw.kiocb;
+		int ret;
 
 		/*
 		 * Move completed and retryable entries to our local lists.
@@ -2301,22 +2300,20 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 			break;
 
 		ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
-		if (ret < 0)
-			break;
+		if (unlikely(ret < 0))
+			return ret;
+		else if (ret)
+			spin = false;
 
 		/* iopoll may have completed current req */
 		if (READ_ONCE(req->iopoll_completed))
 			list_move_tail(&req->inflight_entry, &done);
-
-		if (ret && spin)
-			spin = false;
-		ret = 0;
 	}
 
 	if (!list_empty(&done))
 		io_iopoll_complete(ctx, nr_events, &done, resubmit);
 
-	return ret;
+	return 0;
 }
 
 /*
-- 
2.32.0


  parent reply	other threads:[~2021-07-29 15:06 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-29 15:05 [PATCH for-next 00/23] first 5.15 batch Pavel Begunkov
2021-07-29 15:05 ` [PATCH 01/23] io_uring: remove unnecessary PF_EXITING check Pavel Begunkov
2021-07-29 15:05 ` [PATCH 02/23] io-wq: improve wq_list_add_tail() Pavel Begunkov
2021-07-29 15:05 ` [PATCH 03/23] io_uring: refactor io_alloc_req Pavel Begunkov
2021-07-29 15:05 ` Pavel Begunkov [this message]
2021-07-29 15:05 ` [PATCH 05/23] io_uring: add more locking annotations for submit Pavel Begunkov
2021-07-29 15:05 ` [PATCH 06/23] io_uring: optimise io_cqring_wait() hot path Pavel Begunkov
2021-07-29 15:05 ` [PATCH 07/23] io_uring: extract a helper for ctx quiesce Pavel Begunkov
2021-07-29 15:05 ` [PATCH 08/23] io_uring: move io_put_task() definition Pavel Begunkov
2021-07-29 15:05 ` [PATCH 09/23] io_uring: move io_rsrc_node_alloc() definition Pavel Begunkov
2021-07-29 15:05 ` [PATCH 10/23] io_uring: inline io_free_req_deferred Pavel Begunkov
2021-07-29 15:05 ` [PATCH 11/23] io_uring: deduplicate open iopoll check Pavel Begunkov
2021-07-29 15:05 ` [PATCH 12/23] io_uring: improve ctx hang handling Pavel Begunkov
2021-07-29 15:05 ` [PATCH 13/23] io_uring: kill unused IO_IOPOLL_BATCH Pavel Begunkov
2021-07-29 15:05 ` [PATCH 14/23] io_uring: drop exec checks from io_req_task_submit Pavel Begunkov
2021-07-29 15:05 ` [PATCH 15/23] io_uring: optimise putting task struct Pavel Begunkov
2021-07-29 15:05 ` [PATCH 16/23] io_uring: hide async dadta behind flags Pavel Begunkov
2021-07-29 15:05 ` [PATCH 17/23] io_uring: move io_fallback_req_func() Pavel Begunkov
2021-07-29 15:05 ` [PATCH 18/23] io_uring: cache __io_free_req()'d requests Pavel Begunkov
2021-07-29 15:05 ` [PATCH 19/23] io_uring: use inflight_entry instead of compl.list Pavel Begunkov
2021-07-29 15:05 ` [PATCH 20/23] io_uring: remove redundant args from cache_free Pavel Begunkov
2021-07-29 15:05 ` [PATCH 21/23] io_uring: inline struct io_comp_state Pavel Begunkov
2021-07-29 15:05 ` [PATCH 22/23] io_uring: remove extra argument for overflow flush Pavel Begunkov
2021-07-29 15:05 ` [PATCH 23/23] io_uring: inline io_poll_remove_waitqs Pavel Begunkov

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