linux-kernel - Re: [PATCH 2/3] virtio_console: fixup potential cpu stall when free unused bufs

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Date:   Sat, 10 Jun 2023 11:19:03 +0800
From:   Xianting Tian <xianting.tian@...ux.alibaba.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     arei.gonglei@...wei.com, jasowang@...hat.com,
        xuanzhuo@...ux.alibaba.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, amit@...nel.org, arnd@...db.de,
        gregkh@...uxfoundation.org, marcel@...tmann.org,
        johan.hedberg@...il.com, luiz.dentz@...il.com,
        linux-bluetooth@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] virtio_console: fixup potential cpu stall when free
 unused bufs


在 2023/6/10 上午12:05, Michael S. Tsirkin 写道:
> On Fri, Jun 09, 2023 at 09:18:16PM +0800, Xianting Tian wrote:
>> Cpu stall issue may happen if device is configured with multi queues
>> and large queue depth, so fix it.
> "may happen" is ambigous.
>
> So is this: "for virtio-net we were getting
> stall on CPU was observed message, this driver is similar
> so theoretically the same logic applies"

It is this one

  “this driver is similar so theoretically the same logic applies”

>
> or is this
>
> "the following error occured: ....."
>
> ?
>
>
>> Signed-off-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
>> ---
>>   drivers/char/virtio_console.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
>> index b65c809a4e97..5ec4cf4ea919 100644
>> --- a/drivers/char/virtio_console.c
>> +++ b/drivers/char/virtio_console.c
>> @@ -1935,6 +1935,7 @@ static void remove_vqs(struct ports_device *portdev)
>>   		flush_bufs(vq, true);
>>   		while ((buf = virtqueue_detach_unused_buf(vq)))
>>   			free_buf(buf, true);
>> +		cond_resched();
>>   	}
>>   	portdev->vdev->config->del_vqs(portdev->vdev);
>>   	kfree(portdev->in_vqs);
>> -- 
>> 2.17.1