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authorEric Dumazet <edumazet@google.com>2013-05-15 15:38:01 +0000
committerDavid S. Miller <davem@davemloft.net>2013-05-16 14:43:40 -0700
commit6ff50cd55545d922f5c62776fe1feb38a9846168 (patch)
treecf3a50a628e14fe105a04050823e3051aebf92f3 /net/ipv4
parent5c4b274981950049af3330f14ed9e9aa25afb2fb (diff)
tcp: gso: do not generate out of order packets
GSO TCP handler has following issues : 1) ooo_okay from original GSO packet is duplicated to all segments 2) segments (but the last one) are orphaned, so transmit path can not get transmit queue number from the socket. This happens if GSO segmentation is done before stacked device for example. Result is we can send packets from a given TCP flow to different TX queues (if using multiqueue NICS). This generates OOO problems and spurious SACK & retransmits. Fix this by keeping socket pointer set for all segments. This means that every segment must also have a destructor, and the original gso skb truesize must be split on all segments, to keep precise sk->sk_wmem_alloc accounting. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Maciej Żenczykowski <maze@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp.c22
1 files changed, 21 insertions, 1 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 10c93930abd..ab450c099aa 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2887,6 +2887,7 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
unsigned int mss;
struct sk_buff *gso_skb = skb;
__sum16 newcheck;
+ bool ooo_okay, copy_destructor;
if (!pskb_may_pull(skb, sizeof(*th)))
goto out;
@@ -2927,10 +2928,18 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
goto out;
}
+ copy_destructor = gso_skb->destructor == tcp_wfree;
+ ooo_okay = gso_skb->ooo_okay;
+ /* All segments but the first should have ooo_okay cleared */
+ skb->ooo_okay = 0;
+
segs = skb_segment(skb, features);
if (IS_ERR(segs))
goto out;
+ /* Only first segment might have ooo_okay set */
+ segs->ooo_okay = ooo_okay;
+
delta = htonl(oldlen + (thlen + mss));
skb = segs;
@@ -2950,6 +2959,17 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
thlen, skb->csum));
seq += mss;
+ if (copy_destructor) {
+ skb->destructor = gso_skb->destructor;
+ skb->sk = gso_skb->sk;
+ /* {tcp|sock}_wfree() use exact truesize accounting :
+ * sum(skb->truesize) MUST be exactly be gso_skb->truesize
+ * So we account mss bytes of 'true size' for each segment.
+ * The last segment will contain the remaining.
+ */
+ skb->truesize = mss;
+ gso_skb->truesize -= mss;
+ }
skb = skb->next;
th = tcp_hdr(skb);
@@ -2962,7 +2982,7 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
* is freed at TX completion, and not right now when gso_skb
* is freed by GSO engine
*/
- if (gso_skb->destructor == tcp_wfree) {
+ if (copy_destructor) {
swap(gso_skb->sk, skb->sk);
swap(gso_skb->destructor, skb->destructor);
swap(gso_skb->truesize, skb->truesize);