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

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Xianting Tian <xianting.tian@linux.alibaba.com>
Cc: xuanzhuo@linux.alibaba.com, herbert@gondor.apana.org.au,
	arnd@arndb.de, amit@kernel.org, gregkh@linuxfoundation.org,
	marcel@holtmann.org, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-bluetooth@vger.kernel.org, linux-crypto@vger.kernel.org,
	luiz.dentz@gmail.com, davem@davemloft.net,
	johan.hedberg@gmail.com
Subject: Re: [PATCH 2/3] virtio_console: fixup potential cpu stall when free unused bufs
Date: Fri, 9 Jun 2023 12:05:50 -0400	[thread overview]
Message-ID: <20230609120332-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20230609131817.712867-3-xianting.tian@linux.alibaba.com>

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"

or is this

"the following error occured: ..... "

?

> Signed-off-by: Xianting Tian <xianting.tian@linux.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

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