From: Stefano Garzarella <sgarzare@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
io-uring@vger.kernel.org
Subject: [PATCH] io_uring: flush overflowed CQ events in the io_uring_poll()
Date: Fri, 7 Feb 2020 13:18:28 +0100 [thread overview]
Message-ID: <20200207121828.105456-1-sgarzare@redhat.com> (raw)
In io_uring_poll() we must flush overflowed CQ events before to
check if there are CQ events available, to avoid missing events.
We call the io_cqring_events() that checks and flushes any overflow
and returns the number of CQ events available.
We can avoid taking the 'uring_lock' since the flush is already
protected by 'completion_lock'.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
fs/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 77f22c3da30f..02e77e86abaf 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6301,7 +6301,7 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait)
if (READ_ONCE(ctx->rings->sq.tail) - ctx->cached_sq_head !=
ctx->rings->sq_ring_entries)
mask |= EPOLLOUT | EPOLLWRNORM;
- if (READ_ONCE(ctx->rings->cq.head) != ctx->cached_cq_tail)
+ if (io_cqring_events(ctx, false))
mask |= EPOLLIN | EPOLLRDNORM;
return mask;
--
2.24.1
next reply other threads:[~2020-02-07 12:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-07 12:18 Stefano Garzarella [this message]
2020-02-07 16:12 ` [PATCH] io_uring: flush overflowed CQ events in the io_uring_poll() Jens Axboe
2020-02-07 16:38 ` Stefano Garzarella
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