linux-kernel - Re: [PATCH] virtio_net: Use BUG_ON instead of if condition followed by BUG

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Message-ID: <32044caf-8da4-8bbd-86d6-693ab284351c@linux.alibaba.com>
Date:   Tue, 18 May 2021 17:20:36 +0800
From:   Xianting Tian <xianting.tian@...ux.alibaba.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     mst@...hat.com, jasowang@...hat.com, davem@...emloft.net,
        kuba@...nel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] virtio_net: Use BUG_ON instead of if condition followed
 by BUG

thanks for your comments,
It is a good idea, I think we can follow the similar logic in function 
'receive_buf':
	if (virtio_net_hdr_to_skb(skb, &hdr->hdr,
				  virtio_is_little_endian(vi->vdev))) {
		net_warn_ratelimited("%s: bad gso: type: %u, size:%u\n",
				     dev->name, hdr->hdr.gso_type,
				     hdr->hdr.gso_size);
		goto frame_err;
	}

I will summit a new patch later.


在 2021/5/17 下午10:35, Andrew Lunn 写道:
> On Mon, May 17, 2021 at 09:31:19PM +0800, Xianting Tian wrote:
>> BUG_ON() uses unlikely in if(), which can be optimized at compile time.
>>
>> Signed-off-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
>> ---
>>   drivers/net/virtio_net.c | 5 ++---
>>   1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index c921ebf3ae82..212d52204884 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -1646,10 +1646,9 @@ static int xmit_skb(struct send_queue *sq, struct
>> sk_buff *skb)
>>   	else
>>   		hdr = skb_vnet_hdr(skb);
>>
>> -	if (virtio_net_hdr_from_skb(skb, &hdr->hdr,
> 
> How fatal is it not being able to get the header from the skb? There
> has been push back on the use of BUG() or its variants, since it kills
> the machine dead. Would it be possible to turn this into a WARN_ON and
> return -EPROTO or something?
> 
>         Andrew
>