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[net-next,1/6] net: Add skb_get_hash_perturb

Message ID 1425247789-21211-2-git-send-email-therbert@google.com
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

Tom Herbert March 1, 2015, 10:09 p.m. UTC 
This is used to get the skb->hash and then perturb it for a local use.

Signed-off-by: Tom Herbert <therbert@google.com>
---
 include/linux/skbuff.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
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Patch

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d898b32..48c1978 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -17,6 +17,7 @@ 
 #include <linux/kernel.h>
 #include <linux/kmemcheck.h>
 #include <linux/compiler.h>
+#include <linux/jhash.h>
 #include <linux/time.h>
 #include <linux/bug.h>
 #include <linux/cache.h>
@@ -922,6 +923,20 @@  static inline __u32 skb_get_hash(struct sk_buff *skb)
 	return skb->hash;
 }
 
+static inline __u32 skb_get_hash_perturb(struct sk_buff *skb,
+					 u32 perturb)
+{
+	u32 hash = skb_get_hash(skb);
+
+	if (likely(hash)) {
+		hash = jhash_1word((__force __u32) hash, perturb);
+		if (unlikely(!hash))
+			hash = 1;
+	}
+
+	return hash;
+}
+
 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
 {
 	return skb->hash;