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From: Paolo Bonzini <pbonzini@redhat.com>
To: Fam Zheng <famz@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>
Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org,
	Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v2 02/13] block: Introduce bdrv_lock and bdrv_unlock API
Date: Wed, 24 Jun 2015 11:14:50 +0200	[thread overview]
Message-ID: <558A750A.9070604@redhat.com> (raw)
In-Reply-To: <20150624024747.GC1264@ad.nay.redhat.com>



On 24/06/2015 04:47, Fam Zheng wrote:
>> > 2. Is this about thread safety?  (No, it's about exclusive access to a
>> >    BDS *within* the AioContext.)
> As it has to quiesce iothreads as well (for now it's even more urgent than
> exclusive access within the same AioContext), I'd rather take it as yes.

For now it's a "no", because there are no races between threads: the
main thread has acquired the AioContext and cut away the iothread.

However, as we move towards fine-grained AioContext critical sections,
it will become a "yes".

Paolo

  parent reply	other threads:[~2015-06-24  9:15 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-02  3:21 [Qemu-devel] [PATCH v2 00/13] block: Protect block jobs with lock / unlock API Fam Zheng
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 01/13] block: Use bdrv_drain to replace uncessary bdrv_drain_all Fam Zheng
2015-06-16 16:01   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2015-07-07 11:55     ` Stefan Hajnoczi
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 02/13] block: Introduce bdrv_lock and bdrv_unlock API Fam Zheng
2015-06-16 16:07   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2015-06-24  2:47     ` Fam Zheng
2015-06-24  3:04       ` Fam Zheng
2015-06-24  9:14       ` Paolo Bonzini [this message]
2015-06-24  9:35       ` Stefan Hajnoczi
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 03/13] blockdev: Lock BDS during internal snapshot transaction Fam Zheng
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 04/13] blockdev: Lock BDS during external " Fam Zheng
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 05/13] blockdev: Lock BDS during drive-backup transaction Fam Zheng
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 06/13] blockdev: Lock BDS during blockdev-backup transaction Fam Zheng
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 07/13] mirror: Protect source between bdrv_drain and bdrv_swap Fam Zheng
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 08/13] block: Add bdrv_add_lock_unlock_notifier Fam Zheng
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 09/13] block-backend: Add blk_add_lock_unlock_notifier Fam Zheng
2015-06-02  3:21 ` [Qemu-devel] [PATCH v2 10/13] virtio-blk: Move complete_request to 'ops' structure Fam Zheng
2015-06-02  3:22 ` [Qemu-devel] [PATCH v2 11/13] virtio-blk: Don't handle output when backend is locked Fam Zheng
2015-06-02  3:22 ` [Qemu-devel] [PATCH v2 12/13] virtio-scsi-dataplane: Add backend lock listener Fam Zheng
2015-06-02  3:22 ` [Qemu-devel] [PATCH v2 13/13] nbd-server: Clear "can_read" when backend is locked Fam Zheng

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