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Re: [Qemu-devel] [PATCH 1/1] virtio-blk: fix race on guest notifiers
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH 1/1] virtio-blk: fix race on guest notifiers |
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Date: |
Thu, 2 Mar 2017 17:21:39 +0100 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 |
On 02/03/2017 16:55, Halil Pasic wrote:
>>>> blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
> I'm wondering if synchronization is needed for batch_notify_vqs. I think
> the set_bit can be from the iothread, but the notify_guest_bh below is main
> event loop. Is it OK like this (could we miss bits set in other thread)?
> Does blk_set_aio_context include a barrier?
Another good question---yes, it does (via bdrv_set_aio_context's call to
aio_context_acquire).
But it's something to remember for when I get round to removing
aio_context_acquire!
Paolo