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Re: [Xen-devel] [PATCH net-next] xen-netback: Fix pull size in checksum_setup_ip*



Or would it make sense to drop header_size and use off + something as function parameters?

Zoli

On 29/11/13 18:56, Zoltan Kiss wrote:
Before checksum setup we need to make sure we have enough data in linear
buffer, so we do a pull if not. The calculation of the required data counts
with skb->network_header, which is the headroom size actually. This is not
necessary, and can cause unreasonable pulling. I've also removed
MAX_IPOPTLEN, as we only need the base header at that point.

Signed-off-by: Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>

---
  drivers/net/xen-netback/netback.c |   24 ++++++++----------------
  1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index 919b650..adadf76 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1169,8 +1169,7 @@ static int checksum_setup_ip(struct xenvif *vif, struct 
sk_buff *skb,

        off = sizeof(struct iphdr);

-       header_size = skb->network_header + off + MAX_IPOPTLEN;
-       maybe_pull_tail(skb, header_size);
+       maybe_pull_tail(skb, off);

        off = iph->ihl * 4;

@@ -1183,8 +1182,7 @@ static int checksum_setup_ip(struct xenvif *vif, struct 
sk_buff *skb,
                if (recalculate_partial_csum) {
                        struct tcphdr *tcph = tcp_hdr(skb);

-                       header_size = skb->network_header +
-                               off +
+                       header_size = off +
                                sizeof(struct tcphdr);
                        maybe_pull_tail(skb, header_size);

@@ -1201,8 +1199,7 @@ static int checksum_setup_ip(struct xenvif *vif, struct 
sk_buff *skb,
                if (recalculate_partial_csum) {
                        struct udphdr *udph = udp_hdr(skb);

-                       header_size = skb->network_header +
-                               off +
+                       header_size = off +
                                sizeof(struct udphdr);
                        maybe_pull_tail(skb, header_size);

@@ -1241,8 +1238,7 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct 
sk_buff *skb,

        off = sizeof(struct ipv6hdr);

-       header_size = skb->network_header + off;
-       maybe_pull_tail(skb, header_size);
+       maybe_pull_tail(skb, off);

        nexthdr = ipv6h->nexthdr;

@@ -1254,8 +1250,7 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct 
sk_buff *skb,
                case IPPROTO_ROUTING: {
                        struct ipv6_opt_hdr *hp = (void *)(skb->data + off);

-                       header_size = skb->network_header +
-                               off +
+                       header_size = off +
                                sizeof(struct ipv6_opt_hdr);
                        maybe_pull_tail(skb, header_size);

@@ -1266,8 +1261,7 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct 
sk_buff *skb,
                case IPPROTO_AH: {
                        struct ip_auth_hdr *hp = (void *)(skb->data + off);

-                       header_size = skb->network_header +
-                               off +
+                       header_size = off +
                                sizeof(struct ip_auth_hdr);
                        maybe_pull_tail(skb, header_size);

@@ -1305,8 +1299,7 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct 
sk_buff *skb,
                if (recalculate_partial_csum) {
                        struct tcphdr *tcph = tcp_hdr(skb);

-                       header_size = skb->network_header +
-                               off +
+                       header_size = off +
                                sizeof(struct tcphdr);
                        maybe_pull_tail(skb, header_size);

@@ -1324,8 +1317,7 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct 
sk_buff *skb,
                if (recalculate_partial_csum) {
                        struct udphdr *udph = udp_hdr(skb);

-                       header_size = skb->network_header +
-                               off +
+                       header_size = off +
                                sizeof(struct udphdr);
                        maybe_pull_tail(skb, header_size);




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