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References: <20170418103948.13965-1-famz@redhat.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <3b51de74-0d1b-ebae-1b98-fa74d028c982@redhat.com>
Date: Tue, 18 Apr 2017 14:36:45 +0200
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Subject: Re: [Qemu-devel] [PATCH for-2.9-rc5 v3] block: Drain BH in
 bdrv_drained_begin
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To: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org
Cc: qemu-block@nongnu.org, jcody@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>



On 18/04/2017 12:39, Fam Zheng wrote:
> +    QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
> +        BlockDriverState *bs = child->bs;
> +        assert(bs->refcnt > 0);
> +        bdrv_ref(bs);
> +        waited |= bdrv_drain_recurse(bs);
> +        bdrv_unref(bs);
>      }

I think this accesses global state that is not protected by the
AioContext lock?

Paolo