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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2011-10-17 19:07:30 -0400
committerDavid S. Miller <davem@davemloft.net>2011-10-17 19:07:30 -0400
commitf36c23bb9f822904dacf83a329518d0a5fde7968 (patch)
treefc7808103cdf00bb8a42247fccf638014798dd35 /include/net/udplite.h
parentMerge branch 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging (diff)
downloadlinux-dev-f36c23bb9f822904dacf83a329518d0a5fde7968.tar.xz
linux-dev-f36c23bb9f822904dacf83a329518d0a5fde7968.zip
udplite: fast-path computation of checksum coverage
Commit 903ab86d195cca295379699299c5fc10beba31c7 of 1 March this year ("udp: Add lockless transmit path") introduced a new fast TX path that broke the checksum coverage computation of UDP-lite, which so far depended on up->len (only set if the socket is locked and 0 in the fast path). Fixed by providing both fast- and slow-path computation of checksum coverage. The latter can be removed when UDP(-lite)v6 also uses a lockless transmit path. Reported-by: Thomas Volkert <thomas@homer-conferencing.com> Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/udplite.h')
-rw-r--r--include/net/udplite.h63
1 files changed, 31 insertions, 32 deletions
diff --git a/include/net/udplite.h b/include/net/udplite.h
index 673a024c6b2a..5f097ca7d5c5 100644
--- a/include/net/udplite.h
+++ b/include/net/udplite.h
@@ -66,40 +66,34 @@ static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
return 0;
}
-static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh)
+/* Slow-path computation of checksum. Socket is locked. */
+static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
{
+ const struct udp_sock *up = udp_sk(skb->sk);
int cscov = up->len;
+ __wsum csum = 0;
- /*
- * Sender has set `partial coverage' option on UDP-Lite socket
- */
- if (up->pcflag & UDPLITE_SEND_CC) {
+ if (up->pcflag & UDPLITE_SEND_CC) {
+ /*
+ * Sender has set `partial coverage' option on UDP-Lite socket.
+ * The special case "up->pcslen == 0" signifies full coverage.
+ */
if (up->pcslen < up->len) {
- /* up->pcslen == 0 means that full coverage is required,
- * partial coverage only if 0 < up->pcslen < up->len */
- if (0 < up->pcslen) {
- cscov = up->pcslen;
- }
- uh->len = htons(up->pcslen);
+ if (0 < up->pcslen)
+ cscov = up->pcslen;
+ udp_hdr(skb)->len = htons(up->pcslen);
}
- /*
- * NOTE: Causes for the error case `up->pcslen > up->len':
- * (i) Application error (will not be penalized).
- * (ii) Payload too big for send buffer: data is split
- * into several packets, each with its own header.
- * In this case (e.g. last segment), coverage may
- * exceed packet length.
- * Since packets with coverage length > packet length are
- * illegal, we fall back to the defaults here.
- */
+ /*
+ * NOTE: Causes for the error case `up->pcslen > up->len':
+ * (i) Application error (will not be penalized).
+ * (ii) Payload too big for send buffer: data is split
+ * into several packets, each with its own header.
+ * In this case (e.g. last segment), coverage may
+ * exceed packet length.
+ * Since packets with coverage length > packet length are
+ * illegal, we fall back to the defaults here.
+ */
}
- return cscov;
-}
-
-static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
-{
- int cscov = udplite_sender_cscov(udp_sk(sk), udp_hdr(skb));
- __wsum csum = 0;
skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
@@ -115,16 +109,21 @@ static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
return csum;
}
+/* Fast-path computation of checksum. Socket may not be locked. */
static inline __wsum udplite_csum(struct sk_buff *skb)
{
- struct sock *sk = skb->sk;
- int cscov = udplite_sender_cscov(udp_sk(sk), udp_hdr(skb));
+ const struct udp_sock *up = udp_sk(skb->sk);
const int off = skb_transport_offset(skb);
- const int len = skb->len - off;
+ int len = skb->len - off;
+ if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) {
+ if (0 < up->pcslen)
+ len = up->pcslen;
+ udp_hdr(skb)->len = htons(up->pcslen);
+ }
skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
- return skb_checksum(skb, off, min(cscov, len), 0);
+ return skb_checksum(skb, off, len, 0);
}
extern void udplite4_register(void);