From: Paolo Bonzini <pbonzini@redhat.com>
To: Jiri Slaby <jslaby@suse.cz>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v4 1/1] pci-host: add educational driver
Date: Wed, 21 Jan 2015 17:40:23 +0100 [thread overview]
Message-ID: <54BFD677.2070905@redhat.com> (raw)
In-Reply-To: <1421857693-12014-1-git-send-email-jslaby@suse.cz>
On 21/01/2015 17:28, Jiri Slaby wrote:
> + if (atomic_fetch_or(&edu->status, EDU_STATUS_COMPUTING) & EDU_STATUS_COMPUTING) {
Theoretically the other thread could see EDU_STATUS_COMPUTING here and
not enter the condvar wait. So...
> + break;
> + }
> + qemu_mutex_lock(&edu->thr_mutex);
> + edu->fact = val;
> + qemu_cond_signal(&edu->thr_cond);
> + qemu_mutex_unlock(&edu->thr_mutex);
... just one change:
if (atomic_read(&edu->status) & EDU_STATUS_COMPUTING) {
break;
}
/* EDU_STATUS_COMPUTING cannot go 0->1 concurrently, because
* it is only set in this function and it is under the iothread
* mutex.
*/
qemu_mutex_lock(&edu->thr_mutex);
edu->fact = val;
atomic_or(&edu->status), EDU_STATUS_COMPUTING);
qemu_cond_signal(&edu->thr_cond);
qemu_mutex_unlock(&edu->thr_mutex);
If you are okay with this change, I'll apply the patch to my tree.
Paolo
next prev parent reply other threads:[~2015-01-21 16:40 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-21 16:28 [Qemu-devel] [PATCH v4 1/1] pci-host: add educational driver Jiri Slaby
2015-01-21 16:40 ` Paolo Bonzini [this message]
2015-01-21 16:44 ` Jiri Slaby
2015-01-21 16:48 ` [Qemu-devel] [PATCH v5 1/1] hw: misc, " Jiri Slaby
2015-01-21 16:58 ` Paolo Bonzini
2015-01-21 23:37 ` Eric Blake
2015-01-22 8:22 ` [Qemu-devel] [PATCH 1/1] edu: fix license information Jiri Slaby
2015-01-22 9:04 ` Markus Armbruster
2015-01-22 9:04 ` Jiri Slaby
2015-01-22 9:41 ` Markus Armbruster
2015-01-22 15:39 ` Eric Blake
2015-01-22 15:53 ` Paolo Bonzini
2015-01-22 19:10 ` Jiri Slaby
2015-01-23 7:40 ` Markus Armbruster
2015-01-21 23:49 ` [Qemu-devel] [PATCH v5 1/1] hw: misc, add educational driver Eric Blake
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