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Message-ID: <8faa07aa-d330-4e3f-95b7-26437d448beb@redhat.com>
Date: Sat, 30 Mar 2024 19:02:11 +1000
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Subject: Re: [PATCH v3 3/3] vhost: Improve vhost_get_avail_idx() with
 smp_rmb()
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: virtualization@lists.linux.dev, linux-kernel@vger.kernel.org,
 jasowang@redhat.com, will@kernel.org, davem@davemloft.net,
 stefanha@redhat.com, sgarzare@redhat.com, keirf@google.com,
 yihyu@redhat.com, shan.gavin@gmail.com
References: <20240328002149.1141302-1-gshan@redhat.com>
 <20240328002149.1141302-4-gshan@redhat.com>
 <20240328052814-mutt-send-email-mst@kernel.org>
From: Gavin Shan <gshan@redhat.com>
In-Reply-To: <20240328052814-mutt-send-email-mst@kernel.org>
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On 3/28/24 19:31, Michael S. Tsirkin wrote:
> On Thu, Mar 28, 2024 at 10:21:49AM +1000, Gavin Shan wrote:
>> All the callers of vhost_get_avail_idx() are concerned to the memory
>> barrier, imposed by smp_rmb() to ensure the order of the available
>> ring entry read and avail_idx read.
>>
>> Improve vhost_get_avail_idx() so that smp_rmb() is executed when
>> the avail_idx is advanced. With it, the callers needn't to worry
>> about the memory barrier.
>>
>> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
>> Signed-off-by: Gavin Shan <gshan@redhat.com>
> 
> Previous patches are ok. This one I feel needs more work -
> first more code such as sanity checking should go into
> this function, second there's actually a difference
> between comparing to last_avail_idx and just comparing
> to the previous value of avail_idx.
> I will pick patches 1-2 and post a cleanup on top so you can
> take a look, ok?
> 

Thanks, Michael. It's fine to me.

Thanks,
Gavin