diff mbox

deal with if frags[0].size is pulled to 0 in dev_gro_receive()

Message ID 1280805439-18988-1-git-send-email-xiaohui.xin@intel.com
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Xin, Xiaohui Aug. 3, 2010, 3:17 a.m. UTC 
From: Xin Xiaohui <xiaohui.xin@intel.com>

Now in dev_gro_receive(), if frags[0].size is pulled to 0, memmove is called and
the null page is released. But it's not enough, we should reset size of each frags
left as well. Compared to this, we can have another way to do this, it's not do do
anything at all.

Signed-off-by: Xin Xiaohui <xiaohui.xin@intel.com>

---
 net/core/dev.c |    7 -------
 1 files changed, 0 insertions(+), 7 deletions(-)

Comments

Herbert Xu Aug. 3, 2010, 4:56 a.m. UTC | #1 
On Tue, Aug 03, 2010 at 11:17:19AM +0800, xiaohui.xin@intel.com wrote:
> From: Xin Xiaohui <xiaohui.xin@intel.com>
> 
> Now in dev_gro_receive(), if frags[0].size is pulled to 0, memmove is called and
> the null page is released. But it's not enough, we should reset size of each frags
> left as well. Compared to this, we can have another way to do this, it's not do do
> anything at all.
> 
> Signed-off-by: Xin Xiaohui <xiaohui.xin@intel.com>

This patch can only work if you audit everything that uses skb
frags to ensure that they can tolerate a zero-sided frag.

I think it's much easier to just fix the memmove.

Thanks,
David Miller Aug. 3, 2010, 5:03 a.m. UTC | #2 
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Tue, 3 Aug 2010 12:56:38 +0800

> On Tue, Aug 03, 2010 at 11:17:19AM +0800, xiaohui.xin@intel.com wrote:
>> From: Xin Xiaohui <xiaohui.xin@intel.com>
>> 
>> Now in dev_gro_receive(), if frags[0].size is pulled to 0, memmove is called and
>> the null page is released. But it's not enough, we should reset size of each frags
>> left as well. Compared to this, we can have another way to do this, it's not do do
>> anything at all.
>> 
>> Signed-off-by: Xin Xiaohui <xiaohui.xin@intel.com>
> 
> This patch can only work if you audit everything that uses skb
> frags to ensure that they can tolerate a zero-sided frag.
> 
> I think it's much easier to just fix the memmove.

Agreed.
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diff mbox

Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index 264137f..28cdbbf 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2730,13 +2730,6 @@  pull:
 
 		skb_shinfo(skb)->frags[0].page_offset += grow;
 		skb_shinfo(skb)->frags[0].size -= grow;
-
-		if (unlikely(!skb_shinfo(skb)->frags[0].size)) {
-			put_page(skb_shinfo(skb)->frags[0].page);
-			memmove(skb_shinfo(skb)->frags,
-				skb_shinfo(skb)->frags + 1,
-				--skb_shinfo(skb)->nr_frags);
-		}
 	}
 
 ok: