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bpf, sockmap: Call skb_linearize only when required in sk_psock_skb_ingress_enqueue

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The skb_to_sgvec fails only when the number of frag_list and frags
exceeds MAX_MSG_FRAGS. Therefore, we can call skb_linearize only
when the conversion fails.

Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220427115150.210213-1-liujian56@huawei.com
This commit is contained in:
Liu Jian 2022-04-27 19:51:50 +08:00 committed by Daniel Borkmann
parent 9a9a90ca13
commit 3527bfe6a9
1 changed files with 13 additions and 9 deletions
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22
net/core/skmsg.c
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@ -524,16 +524,20 @@ static int sk_psock_skb_ingress_enqueue(struct sk_buff *skb,
{
int num_sge, copied;
/* skb linearize may fail with ENOMEM, but lets simply try again
* later if this happens. Under memory pressure we don't want to
* drop the skb. We need to linearize the skb so that the mapping
* in skb_to_sgvec can not error.
*/
if (skb_linearize(skb))
return -EAGAIN;
num_sge = skb_to_sgvec(skb, msg->sg.data, off, len);
if (unlikely(num_sge < 0))
return num_sge;
if (num_sge < 0) {
/* skb linearize may fail with ENOMEM, but lets simply try again
* later if this happens. Under memory pressure we don't want to
* drop the skb. We need to linearize the skb so that the mapping
* in skb_to_sgvec can not error.
*/
if (skb_linearize(skb))
return -EAGAIN;
num_sge = skb_to_sgvec(skb, msg->sg.data, off, len);
if (unlikely(num_sge < 0))
return num_sge;
}
copied = len;
msg->sg.start = 0;