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From: Stefano Garzarella <[email protected]>
To: Jens Axboe <[email protected]>
Cc: [email protected], [email protected],
	Alexander Viro <[email protected]>,
	[email protected]
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: <[email protected]> (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 <[email protected]>
---
 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


             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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