All Virtuozzo development lists (kernel + QEMU)
 help / color / mirror / Atom feed
From: no-reply@sashiko.virtuozzo.com
To: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>,
	alexander.ivanov@virtuozzo.com, khorenko@virtuozzo.com
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 v6 5/7] dm/push_backup: arm deadline timer under pb->lock
Date: Wed, 4 Nov 2026 08:48:04 +0000	[thread overview]
Message-ID: <010701a1a5be7488-9cfc6ee9-21ff-43a0-978c-4c8f731f2377-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261104083818.856720-6-andrey.zhadchenko@virtuozzo.com>

> Both pb_timer_func() and postpone_if_required_for_backup() decide
> whether to arm the timer under pb->lock but call mod_timer() after
> dropping it, so the decisions can be applied out of order:
> 
>   CPU1 pb_timer_func()            CPU2 postpone_if_required_for_backup()
>   lock; deadline = S64_MAX
>   unlock
>                                   lock; nr_delayed = 1
>                                   deadline_jiffies = now + timeout
>                                   unlock
>                                   mod_timer(timeout)
>   mod_timer(from S64_MAX)
> 
> The late mod_timer() of the callback overwrites the fresh deadline, and
> the write is delayed with the timer parked in a very distant future.
> [ ... ]
> Fixes: 62e07487348e ("dm: Add push backup driver")
> https://virtuozzo.atlassian.net/browse/VSTOR-152912
> 
> Feature: dm-backup: push backup target driver
> Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261104083818.856720-1-andrey.zhadchenko@virtuozzo.com?part=5


_______________________________________________
Devel mailing list
Devel@openvz.org
https://lists.openvz.org/mailman/listinfo/devel

  reply	other threads:[~2026-11-04  8:49 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-04  8:38 [Devel] [PATCH hci-8.1 v6 0/7] dm/push_backup: event fd interface and fixes Andrey Zhadchenko
2026-11-04  8:38 ` [Devel] [PATCH hci-8.1 v6 1/7] dm/push_backup: correct initialization Andrey Zhadchenko
2026-11-04  8:45   ` no-reply
2026-11-04  8:38 ` [Devel] [PATCH hci-8.1 v6 2/7] dm/push_backup: return error if workqueue allocation fails Andrey Zhadchenko
2026-11-04  8:46   ` no-reply
2026-11-04  8:38 ` [Devel] [PATCH hci-8.1 v6 3/7] dm/push_backup: clear pb->alive under pb->lock Andrey Zhadchenko
2026-11-04  8:46   ` no-reply
2026-11-04  8:38 ` [Devel] [PATCH hci-8.1 v6 4/7] dm/push_backup: fix mod_timer() usage Andrey Zhadchenko
2026-11-04  8:47   ` no-reply
2026-11-04  8:38 ` [Devel] [PATCH hci-8.1 v6 5/7] dm/push_backup: arm deadline timer under pb->lock Andrey Zhadchenko
2026-11-04  8:48   ` no-reply [this message]
2026-11-04  8:38 ` [Devel] [PATCH hci-8.1 v6 6/7] dm/push_backup: do not re-arm deadline timer in push_backup_write() Andrey Zhadchenko
2026-11-04  8:50   ` no-reply
2026-11-04  8:38 ` [Devel] [PATCH hci-8.1 v6 7/7] dm/push_backup: add event file descriptor interface Andrey Zhadchenko
2026-11-04  8:52   ` no-reply
2026-11-04 18:46 ` [Devel] [PATCH hci-8.1 v6 0/7] dm/push_backup: event fd interface and fixes Konstantin Khorenko

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=010701a1a5be7488-9cfc6ee9-21ff-43a0-978c-4c8f731f2377-000000@eu-central-1.amazonses.com \
    --to=no-reply@sashiko.virtuozzo.com \
    --cc=alexander.ivanov@virtuozzo.com \
    --cc=andrey.zhadchenko@virtuozzo.com \
    --cc=devel@openvz.org \
    --cc=khorenko@virtuozzo.com \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.