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From: Alberto Garcia <berto@igalia.com>
To: qemu-devel@nongnu.org
Cc: Alberto Garcia <berto@igalia.com>,
	Jorge Merlino <jorge.merlino@canonical.com>,
	Kevin Wolf <kwolf@redhat.com>,
	qemu-block@nongnu.org, Hanna Czenczek <hreitz@redhat.com>
Subject: [PATCH v3 0/1] Fix race condition in throttle_group_restart_queue()
Date: Thu, 12 Mar 2026 13:11:59 +0100	[thread overview]
Message-ID: <cover.1773316842.git.berto@igalia.com> (raw)

Hi,

In the previous patch I forgot to relax the assertion for case 2.

If we're restarting the queue when another tgm has a timer armed I
don't think we can guarantee that when the timer fires it won't set a
new timer on our own tgm before we reach the assertion.

I think that the assertion should depend on reset_timer_armed:

- If it's true, no one else can arm a timer so the assertion holds.
- If it's false, it is possible for the other tgm to arm our timer.
  The assertion would fail in this case, but I think it's harmless
  because even if it would fire at the same time the logic in
  throttle_group_restart_queue_entry() is protected by the lock.

Berto

Alberto Garcia (1):
  throttle-group: Fix race condition in throttle_group_restart_queue()

 block/throttle-groups.c | 79 +++++++++++++++++++++++++++++++----------
 1 file changed, 60 insertions(+), 19 deletions(-)

-- 
2.47.3



             reply	other threads:[~2026-03-12 12:13 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-12 12:11 Alberto Garcia [this message]
2026-03-12 12:12 ` [PATCH v3 1/1] throttle-group: Fix race condition in throttle_group_restart_queue() Alberto Garcia
2026-03-12 19:44   ` Jorge Merlino
2026-03-16 16:36 ` [PATCH v3 0/1] " Hanna Czenczek

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