From 030737bcc3c404e273e97dbe06fe9561699a411b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 19 Oct 2013 11:42:54 -0700 Subject: [PATCH] net: generalize skb_segment() While implementing GSO/TSO support for IPIP, I found skb_segment() was assuming network header was immediately following mac header. Its not really true in the case inet_gso_segment() is stacked : By the time tcp_gso_segment() is called, network header points to the inner IP header. Let's instead assume nothing and pick the current offsets found in original skb, we have skb_headers_offset_update() helper for that. Also move the csum_start update inside skb_headers_offset_update() Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/skbuff.c | 22 +++++----------------- 1 file changed, 5 insertions(+), 17 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 8ead744fcc94..0ab32faa520f 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -903,6 +903,9 @@ EXPORT_SYMBOL(skb_clone); static void skb_headers_offset_update(struct sk_buff *skb, int off) { + /* Only adjust this if it actually is csum_start rather than csum */ + if (skb->ip_summed == CHECKSUM_PARTIAL) + skb->csum_start += off; /* {transport,network,mac}_header and tail are relative to skb->head */ skb->transport_header += off; skb->network_header += off; @@ -1109,9 +1112,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, #endif skb->tail += off; skb_headers_offset_update(skb, nhead); - /* Only adjust this if it actually is csum_start rather than csum */ - if (skb->ip_summed == CHECKSUM_PARTIAL) - skb->csum_start += nhead; skb->cloned = 0; skb->hdr_len = 0; skb->nohdr = 0; @@ -1176,7 +1176,6 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb, NUMA_NO_NODE); int oldheadroom = skb_headroom(skb); int head_copy_len, head_copy_off; - int off; if (!n) return NULL; @@ -1200,11 +1199,7 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb, copy_skb_header(n, skb); - off = newheadroom - oldheadroom; - if (n->ip_summed == CHECKSUM_PARTIAL) - n->csum_start += off; - - skb_headers_offset_update(n, off); + skb_headers_offset_update(n, newheadroom - oldheadroom); return n; } @@ -2837,14 +2832,7 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) __copy_skb_header(nskb, skb); nskb->mac_len = skb->mac_len; - /* nskb and skb might have different headroom */ - if (nskb->ip_summed == CHECKSUM_PARTIAL) - nskb->csum_start += skb_headroom(nskb) - headroom; - - skb_reset_mac_header(nskb); - skb_set_network_header(nskb, skb->mac_len); - nskb->transport_header = (nskb->network_header + - skb_network_header_len(skb)); + skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom); skb_copy_from_linear_data_offset(skb, -tnl_hlen, nskb->data - tnl_hlen, -- 2.30.2