xfrm: add state hashtable keyed by seq

When creating new states with seq set in xfrm_usersa_info, we walk
through all the states already installed in that netns to find a
matching ACQUIRE state (__xfrm_find_acq_byseq, called from
xfrm_state_add). This causes severe slowdowns on systems with a large
number of states.

This patch introduces a hashtable using x->km.seq as key, so that the
corresponding state can be found in a reasonable time.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_hash.h b/net/xfrm/xfrm_hash.h
index ce66323102f9..d12bb906c9c9 100644
--- a/net/xfrm/xfrm_hash.h
+++ b/net/xfrm/xfrm_hash.h
@@ -131,6 +131,13 @@ __xfrm_spi_hash(const xfrm_address_t *daddr, __be32 spi, u8 proto,
 	return (h ^ (h >> 10) ^ (h >> 20)) & hmask;
 }
 
+static inline unsigned int
+__xfrm_seq_hash(u32 seq, unsigned int hmask)
+{
+	unsigned int h = seq;
+	return (h ^ (h >> 10) ^ (h >> 20)) & hmask;
+}
+
 static inline unsigned int __idx_hash(u32 index, unsigned int hmask)
 {
 	return (index ^ (index >> 8)) & hmask;