diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-03-05 16:47:48 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-03-06 21:50:55 -0500 |
| commit | 58025e46ea2d39f1840d5b1be5edea3297cfd23f (patch) | |
| tree | cf0593edf6cac7b70da9213139ae481a013381c2 /net/core | |
| parent | feb27d155dfabcb8baabe10367f25fc2b1bcede1 (diff) | |
net: gro: remove obsolete code from skb_gro_receive()
Some drivers use copybreak to copy tiny frames into smaller skb,
and this smaller skb might not have skb->head_frag set for various
reasons.
skb_gro_receive() currently doesn't allow to aggregate the smaller skb
into the previous GRO packet if this GRO packet has at least 2 MSS in
it.
Following workload easily demonstrates the problem.
netperf -t TCP_RR -H target -- -r 3000,3000
(tcpdump shows one GRO packet with 2 MSS, plus one additional packet of
104 bytes that should have been appended.)
It turns out that we can remove code from skb_gro_receive(), because
commit 8a29111c7ca6 ("net: gro: allow to build full sized skb") and its
followups removed the assumption that a GRO packet with a frag_list had
to have an empty head.
Removing this code allows the aggregation of the last (incomplete) frame
in some RPC workloads. Note that tcp_gro_receive() already takes care of
forcing a flush if necessary, including this case.
If we want to avoid using frag_list in the first place (in forwarding
workloads for example, as the outgoing NIC is generally not able to cope
with skbs having a frag_list), we need to address this separately.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/skbuff.c | 45 |
1 files changed, 1 insertions, 44 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 913b94a77060..47c32413d5b9 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c | |||
| @@ -3206,10 +3206,9 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) | |||
| 3206 | struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb); | 3206 | struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb); |
| 3207 | unsigned int offset = skb_gro_offset(skb); | 3207 | unsigned int offset = skb_gro_offset(skb); |
| 3208 | unsigned int headlen = skb_headlen(skb); | 3208 | unsigned int headlen = skb_headlen(skb); |
| 3209 | struct sk_buff *nskb, *lp, *p = *head; | ||
| 3210 | unsigned int len = skb_gro_len(skb); | 3209 | unsigned int len = skb_gro_len(skb); |
| 3210 | struct sk_buff *lp, *p = *head; | ||
| 3211 | unsigned int delta_truesize; | 3211 | unsigned int delta_truesize; |
| 3212 | unsigned int headroom; | ||
| 3213 | 3212 | ||
| 3214 | if (unlikely(p->len + len >= 65536)) | 3213 | if (unlikely(p->len + len >= 65536)) |
| 3215 | return -E2BIG; | 3214 | return -E2BIG; |
| @@ -3276,48 +3275,6 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) | |||
| 3276 | NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD; | 3275 | NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD; |
| 3277 | goto done; | 3276 | goto done; |
| 3278 | } | 3277 | } |
| 3279 | /* switch back to head shinfo */ | ||
| 3280 | pinfo = skb_shinfo(p); | ||
| 3281 | |||
| 3282 | if (pinfo->frag_list) | ||
| 3283 | goto merge; | ||
| 3284 | if (skb_gro_len(p) != pinfo->gso_size) | ||
| 3285 | return -E2BIG; | ||
| 3286 | |||
| 3287 | headroom = skb_headroom(p); | ||
| 3288 | nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC); | ||
| 3289 | if (unlikely(!nskb)) | ||
| 3290 | return -ENOMEM; | ||
| 3291 | |||
| 3292 | __copy_skb_header(nskb, p); | ||
| 3293 | nskb->mac_len = p->mac_len; | ||
| 3294 | |||
| 3295 | skb_reserve(nskb, headroom); | ||
| 3296 | __skb_put(nskb, skb_gro_offset(p)); | ||
| 3297 | |||
| 3298 | skb_set_mac_header(nskb, skb_mac_header(p) - p->data); | ||
| 3299 | skb_set_network_header(nskb, skb_network_offset(p)); | ||
| 3300 | skb_set_transport_header(nskb, skb_transport_offset(p)); | ||
| 3301 | |||
| 3302 | __skb_pull(p, skb_gro_offset(p)); | ||
| 3303 | memcpy(skb_mac_header(nskb), skb_mac_header(p), | ||
| 3304 | p->data - skb_mac_header(p)); | ||
| 3305 | |||
| 3306 | skb_shinfo(nskb)->frag_list = p; | ||
| 3307 | skb_shinfo(nskb)->gso_size = pinfo->gso_size; | ||
| 3308 | pinfo->gso_size = 0; | ||
| 3309 | __skb_header_release(p); | ||
| 3310 | NAPI_GRO_CB(nskb)->last = p; | ||
| 3311 | |||
| 3312 | nskb->data_len += p->len; | ||
| 3313 | nskb->truesize += p->truesize; | ||
| 3314 | nskb->len += p->len; | ||
| 3315 | |||
| 3316 | *head = nskb; | ||
| 3317 | nskb->next = p->next; | ||
| 3318 | p->next = NULL; | ||
| 3319 | |||
| 3320 | p = nskb; | ||
| 3321 | 3278 | ||
| 3322 | merge: | 3279 | merge: |
| 3323 | delta_truesize = skb->truesize; | 3280 | delta_truesize = skb->truesize; |