Re: [PATCHv3 net-next 1/2] net: move the hsize check to the else block in skb_segment
From: Alexander Duyck <hidden>
Date: 2021-01-16 01:40:11
Also in:
linux-sctp
On Fri, Jan 15, 2021 at 1:36 AM Xin Long [off-list ref] wrote:
After commit 89319d3801d1 ("net: Add frag_list support to skb_segment"),
it goes to process frag_list when !hsize in skb_segment(). However, when
using skb frag_list, sg normally should not be set. In this case, hsize
will be set with len right before !hsize check, then it won't go to
frag_list processing code.
So the right thing to do is move the hsize check to the else block, so
that it won't affect the !hsize check for frag_list processing.
v1->v2:
- change to do "hsize <= 0" check instead of "!hsize", and also move
"hsize < 0" into else block, to save some cycles, as Alex suggested.
Signed-off-by: Xin Long <lucien.xin@gmail.com>Looks good to me. Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
quoted hunk ↗ jump to hunk
--- net/core/skbuff.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 6039069..e835193 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c@@ -3894,12 +3894,8 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, } hsize = skb_headlen(head_skb) - offset; - if (hsize < 0) - hsize = 0; - if (hsize > len || !sg) - hsize = len; - if (!hsize && i >= nfrags && skb_headlen(list_skb) && + if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) && (skb_headlen(list_skb) == len || sg)) { BUG_ON(skb_headlen(list_skb) > len);@@ -3942,6 +3938,11 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, skb_release_head_state(nskb); __skb_push(nskb, doffset); } else { + if (hsize > len || !sg) + hsize = len; + else if (hsize < 0) + hsize = 0; + nskb = __alloc_skb(hsize + doffset + headroom, GFP_ATOMIC, skb_alloc_rx_flag(head_skb), NUMA_NO_NODE); --2.1.0