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From: Juan Quintela <quintela@redhat.com>
To: Fabiano Rosas <farosas@suse.de>
Cc: "Peter Xu" <peterx@redhat.com>,
	qemu-devel@nongnu.org, "Leonardo Bras" <leobras@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>
Subject: Re: [RFC PATCH 2/2] migration/multifd: Move semaphore release into main thread
Date: Thu, 16 Nov 2023 16:51:11 +0100	[thread overview]
Message-ID: <87jzqhhf2o.fsf@secure.mitica> (raw)
In-Reply-To: <87leb5zsw6.fsf@suse.de> (Fabiano Rosas's message of "Fri, 10 Nov 2023 09:37:13 -0300")

Fabiano Rosas <farosas@suse.de> wrote:
> Fabiano Rosas <farosas@suse.de> writes:
>
>> Peter Xu <peterx@redhat.com> writes:
>>
>>> On Thu, Nov 09, 2023 at 01:58:56PM -0300, Fabiano Rosas wrote:

>> I think we historically stumbled upon the fact that qemu_thread_join()
>> is not the same as pthread_join(). The former takes a pointer and is not
>> safe to call with a NULL QemuThread. That seems to be the reason for the
>> p->running check before it.
>
> Scratch this part, the QemuThread is not a pointer.
>
> ...should it be? Because then we can test p->thread instead of
> p->running, which would be more precise and would dispense the
> thread_created flag.

You still need to make sure that you don't join the thread twice.
And we do the qemu_pthread_join() without any lock.

Later, Juan.



  reply	other threads:[~2023-11-16 15:52 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-09 16:58 [RFC PATCH 0/2] migration: Fix multifd qemu_mutex_destroy race Fabiano Rosas
2023-11-09 16:58 ` [RFC PATCH 1/2] migration: Report error in incoming migration Fabiano Rosas
2023-11-09 18:57   ` Peter Xu
2023-11-10 10:58     ` Fabiano Rosas
2023-11-13 16:51       ` Peter Xu
2023-11-14  1:54         ` Fabiano Rosas
2023-11-09 16:58 ` [RFC PATCH 2/2] migration/multifd: Move semaphore release into main thread Fabiano Rosas
2023-11-09 18:56   ` Peter Xu
2023-11-10 12:05     ` Fabiano Rosas
2023-11-10 12:37       ` Fabiano Rosas
2023-11-16 15:51         ` Juan Quintela [this message]
2023-11-13 16:45       ` Peter Xu
2023-11-14  1:50         ` Fabiano Rosas
2023-11-14 17:28           ` Peter Xu
2023-11-16 15:44       ` Juan Quintela
2023-11-16 14:56     ` Juan Quintela
2023-11-16 18:13       ` Fabiano Rosas

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