On Thu, 2015-08-27 at 08:56 +0800, chenweil...@huawei.com wrote:
> From: Weilong Chen <chenweil...@huawei.com>
>
> When try to merge several skbs to prior one, if the frag_list is
> used and the the last one is a small packet, once the condition
> "len <= skb_tailroom(to)" is satisfied, we will get a wrong
> packet!
> This patch just check frag_lists before the condtion to prevent
> this from happening.
>
> Signed-off-by: Weilong Chen <chenweil...@huawei.com>
> ---
> net/core/skbuff.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 8a725cc..d08edcb 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -4133,6 +4133,9 @@ bool skb_try_coalesce(struct sk_buff *to, struct
> sk_buff *from,
> if (skb_cloned(to))
> return false;
>
> + if (skb_has_frag_list(to) || skb_has_frag_list(from))
> + return false;
> +
> if (len <= skb_tailroom(to)) {
> if (len)
> BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
> @@ -4140,9 +4143,6 @@ bool skb_try_coalesce(struct sk_buff *to, struct
> sk_buff *from,
> return true;
> }
>
> - if (skb_has_frag_list(to) || skb_has_frag_list(from))
> - return false;
> -
> if (skb_headlen(from) != 0) {
> struct page *page;
> unsigned int offset;
Sigh.
No idea what problem you tried to solve.
This patch is not needed.
If (len <= skb_tailroom()), then it is obviously correct to copy_bits()
the bytes.
Hints :
- If @to has a fraglist, then skb_tailroom(to) is 0 so the copy can not
be done.
- If @from has a fraglist, it is not relevant as we copy it into @to and
will free @from.
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