Kernel/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-01-17 10:26:09 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Revert "ipv4: use skb coalescing in defragmentation"

Browse Source 
This reverts commit 3cc4949269e01f39443d0fcfffb5bc6b47878d45.

There is nothing wrong with coalescing during defragmentation, it
reduces truesize overhead and simplifies things for the receiving
socket (no fraglist walk needed).

However, it also destroys geometry of the original fragments.
While that doesn't cause any breakage (we make sure to not exceed largest
original size) ip_do_fragment contains a 'fastpath' that takes advantage
of a present frag list and results in fragments that (in most cases)
match what was received.

In case its needed the coalescing could be done later, when we're sure
the skb is not forwarded.  But discussion during NFWS resulted in
'lets just remove this for now'.

Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2015-07-11 01:37:36 +02:00 committed by David S. Miller
parent 9d7b372f05
commit 14fe22e334
1 changed files with 6 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
net/ipv4/ip_fragment.c
View File

@ -522,7 +522,6 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
int len;
int ihlen;
int err;
int sum_truesize;
u8 ecn;
ipq_kill(qp);
@ -590,32 +589,19 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
add_frag_mem_limit(&qp->q, clone->truesize);
}
skb_shinfo(head)->frag_list = head->next;
skb_push(head, head->data - skb_network_header(head));
sum_truesize = head->truesize;
for (fp = head->next; fp;) {
bool headstolen;
int delta;
struct sk_buff *next = fp->next;
sum_truesize += fp->truesize;
for (fp=head->next; fp; fp = fp->next) {
head->data_len += fp->len;
head->len += fp->len;
if (head->ip_summed != fp->ip_summed)
head->ip_summed = CHECKSUM_NONE;
else if (head->ip_summed == CHECKSUM_COMPLETE)
head->csum = csum_add(head->csum, fp->csum);
if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
kfree_skb_partial(fp, headstolen);
} else {
if (!skb_shinfo(head)->frag_list)
skb_shinfo(head)->frag_list = fp;
head->data_len += fp->len;
head->len += fp->len;
head->truesize += fp->truesize;
}
fp = next;
head->truesize += fp->truesize;
}
sub_frag_mem_limit(&qp->q, sum_truesize);
sub_frag_mem_limit(&qp->q, head->truesize);
head->next = NULL;
head->dev = dev;