From: Peter Xu <peterx@redhat.com>
To: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: qemu-devel <qemu-devel@nongnu.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Eric Blake <eblake@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 1/4] iothread: replace init_done_cond with a semaphore
Date: Fri, 22 Feb 2019 14:36:58 +0800 [thread overview]
Message-ID: <20190222063658.GF8904@xz-x1> (raw)
In-Reply-To: <CAMxuvayiNpRqudM9Ex_3MDYuTvcs3ya-tHmoAhWvCEu70WzUOA@mail.gmail.com>
On Fri, Feb 22, 2019 at 07:25:16AM +0100, Marc-André Lureau wrote:
> Hi
>
> On Fri, Feb 22, 2019 at 4:14 AM Peter Xu <peterx@redhat.com> wrote:
> >
> > Only sending an init-done message using lock+cond seems an overkill to
> > me. Replacing it with a simpler semaphore.
> >
> > Meanwhile, init the semaphore unconditionally, then we can destroy it
> > unconditionally too in finalize which seems cleaner.
> >
> > Signed-off-by: Peter Xu <peterx@redhat.com>
>
> The lock is also protecting thread_id.
IMHO it's fine because thread_id is only changed at the beginning of
iothread_run where the caller will definitely wait for the thread_id
to be generated. Here qemu_sem_post() should at least contain one
write memory barrier there to make sure the waker will read the
correct value after sem_wait() and then later on thread_id is never
changed.
Regards,
--
Peter Xu
next prev parent reply other threads:[~2019-02-22 6:37 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-22 3:14 [Qemu-devel] [PATCH 0/4] iothread: create gcontext unconditionally Peter Xu
2019-02-22 3:14 ` [Qemu-devel] [PATCH 1/4] iothread: replace init_done_cond with a semaphore Peter Xu
2019-02-22 6:25 ` Marc-André Lureau
2019-02-22 6:36 ` Peter Xu [this message]
2019-02-22 9:27 ` Paolo Bonzini
2019-02-22 9:44 ` Marc-André Lureau
2019-02-27 13:26 ` Stefan Hajnoczi
2019-02-22 3:14 ` [Qemu-devel] [PATCH 2/4] iothread: create the gcontext onconditionally Peter Xu
2019-02-22 6:29 ` Marc-André Lureau
2019-02-22 6:47 ` Peter Xu
2019-02-22 3:14 ` [Qemu-devel] [PATCH 3/4] iothread: create main loop unconditionally Peter Xu
2019-02-22 6:30 ` Marc-André Lureau
2019-02-22 3:14 ` [Qemu-devel] [PATCH 4/4] iothread: push gcontext earlier in the thread_fn Peter Xu
2019-02-22 6:37 ` Marc-André Lureau
2019-02-22 6:57 ` Peter Xu
2019-02-22 9:24 ` Paolo Bonzini
2019-02-27 13:38 ` Stefan Hajnoczi
2019-02-28 5:58 ` Peter Xu
2019-03-01 16:25 ` Stefan Hajnoczi
2019-03-04 2:26 ` Peter Xu
2019-03-04 9:12 ` Marc-André Lureau
2019-03-04 9:37 ` Peter Xu
2019-02-22 9:28 ` [Qemu-devel] [PATCH 0/4] iothread: create gcontext unconditionally Paolo Bonzini
2019-02-22 9:45 ` Peter Xu
2019-03-06 10:19 ` Stefan Hajnoczi
2019-03-06 11:44 ` Peter Xu
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