From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org
Subject: Re: [PATCH 3/6] io_uring: fix racy overflow count reporting
Date: Thu, 30 Jul 2020 11:18:15 -0600 [thread overview]
Message-ID: <d2347d32-7651-b34b-a7ca-5993b49a2147@kernel.dk> (raw)
In-Reply-To: <ba9c998d27e8e75467b09d8a2716cf6618b7cd93.1596123376.git.asml.silence@gmail.com>
On 7/30/20 9:43 AM, Pavel Begunkov wrote:
> All ->cq_overflow modifications should be under completion_lock,
> otherwise it can report a wrong number to the userspace. Fix it in
> io_uring_cancel_files().
>
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
> fs/io_uring.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 11f4ab87e08f..6e2322525da6 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -7847,10 +7847,9 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,
> clear_bit(0, &ctx->cq_check_overflow);
> ctx->rings->sq_flags &= ~IORING_SQ_CQ_OVERFLOW;
> }
> - spin_unlock_irq(&ctx->completion_lock);
> -
> WRITE_ONCE(ctx->rings->cq_overflow,
> atomic_inc_return(&ctx->cached_cq_overflow));
> + spin_unlock_irq(&ctx->completion_lock);
Torn writes? Not sure I see what the issue here, can you expand?
--
Jens Axboe
next prev parent reply other threads:[~2020-07-30 17:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-30 15:43 [PATCH 0/6] 5.9 small cleanups/fixes Pavel Begunkov
2020-07-30 15:43 ` [PATCH 1/6] io_uring: de-unionise io_kiocb Pavel Begunkov
2020-07-30 15:43 ` [PATCH 2/6] io_uring: deduplicate __io_complete_rw() Pavel Begunkov
2020-07-30 15:43 ` [PATCH 3/6] io_uring: fix racy overflow count reporting Pavel Begunkov
2020-07-30 17:18 ` Jens Axboe [this message]
2020-07-30 17:33 ` Pavel Begunkov
2020-07-30 17:41 ` Jens Axboe
2020-07-30 15:43 ` [PATCH 4/6] io_uring: fix stalled deferred requests Pavel Begunkov
2020-07-30 15:43 ` [PATCH 5/6] io_uring: consolidate *_check_overflow accounting Pavel Begunkov
2020-07-30 15:43 ` [PATCH 6/6] io_uring: get rid of atomic FAA for cq_timeouts Pavel Begunkov
2020-07-30 18:08 ` [PATCH 0/6] 5.9 small cleanups/fixes Jens Axboe
2020-07-31 14:28 ` Pavel Begunkov
2020-07-31 15:10 ` Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=d2347d32-7651-b34b-a7ca-5993b49a2147@kernel.dk \
--to=axboe@kernel.dk \
--cc=asml.silence@gmail.com \
--cc=io-uring@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).