From: annie li <annie.li@oracle.com>
To: Ian Campbell <ian.campbell@citrix.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
"wei.liu2@citrix.com" <wei.liu2@citrix.com>,
"msw@amazon.com" <msw@amazon.com>,
"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>
Subject: Re: [Xen-devel] [PATCH v2 1/1] xen/netback: correctly calculate required slots of skb.
Date: Thu, 11 Jul 2013 21:35:40 +0800 [thread overview]
Message-ID: <51DEB4AC.8090409@oracle.com> (raw)
In-Reply-To: <1373541144.5453.165.camel@hastur.hellion.org.uk>
On 2013-7-11 19:12, Ian Campbell wrote:
>>>>> The code here only
>>>>> increase count for the first time. I thought to initialize the
>>>>> count in
>>>>> xen_netbk_count_skb_slots with 1 to avoid this. But thinking of
>>>>> the
>>>>> extreme case when the header size is zero(not sure whether this
>>>>> case
>>>>> could be true), I increase the count here to keep safe in case
>>>>> header
>>>>> size is zero.
>>>> netfront requires that the first slot always contains some data,
>>>> gop_frag_copy will BUG if that's not the case.
>>>>
>>
>> In gop_frag_copy, we can not go into the while if the size is 0. Which
>> BUG_ON do you mean here?
> in gop_frag_copy:
> if (start_new_rx_buffer(npo->copy_off, bytes, *head)) {
> /*
> * Netfront requires there to be some data in the head
> * buffer.
> */
> BUG_ON(*head);
>
But If there is SKB with zero header size and zero offset, the code will
not run into the while loop in gop_frag_copy and this if condition.
BUG_ON will not happen in such situation.
Thanks
Annie
next prev parent reply other threads:[~2013-07-11 13:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-10 9:15 [PATCH v2 1/1] xen/netback: correctly calculate required slots of skb Annie Li
2013-07-11 2:18 ` David Miller
2013-07-11 2:48 ` [Xen-devel] " annie li
2013-07-11 19:04 ` David Miller
2013-07-11 8:11 ` Ian Campbell
2013-07-11 8:34 ` annie li
2013-07-11 9:47 ` Ian Campbell
2013-07-11 10:46 ` Annie
2013-07-11 10:59 ` Annie
2013-07-11 11:12 ` [Xen-devel] " Ian Campbell
2013-07-11 13:35 ` annie li [this message]
2013-07-11 20:03 ` David Miller
2013-07-11 21:12 ` [Xen-devel] " Wei Liu
2013-07-16 9:00 ` Ian Campbell
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