[NET]: Convert hh_lock to seqlock.

The hard header cache is in the main output path, so using
seqlock instead of reader/writer lock should reduce overhead.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 5 deletions

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 0ab1987b9348..e7300b6b4079 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -577,9 +577,10 @@ void neigh_destroy(struct neighbour *neigh)
         while ((hh = neigh->hh) != NULL) {
                 neigh->hh = hh->hh_next;
                 hh->hh_next = NULL;
-                write_lock_bh(&hh->hh_lock);
+
+                write_seqlock_bh(&hh->hh_lock);
                 hh->hh_output = neigh_blackhole;
-                write_unlock_bh(&hh->hh_lock);
+                write_sequnlock_bh(&hh->hh_lock);
                 if (atomic_dec_and_test(&hh->hh_refcnt))
                         kfree(hh);
         }
@@ -897,9 +898,9 @@ static void neigh_update_hhs(struct neighbour *neigh)
 
         if (update) {
                 for (hh = neigh->hh; hh; hh = hh->hh_next) {
-                        write_lock_bh(&hh->hh_lock);
+                        write_seqlock_bh(&hh->hh_lock);
                         update(hh, neigh->dev, neigh->ha);
-                        write_unlock_bh(&hh->hh_lock);
+                        write_sequnlock_bh(&hh->hh_lock);
                 }
         }
 }
@@ -1089,7 +1090,7 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst,
                         break;
 
         if (!hh && (hh = kzalloc(sizeof(*hh), GFP_ATOMIC)) != NULL) {
-                rwlock_init(&hh->hh_lock);
+                seqlock_init(&hh->hh_lock);
                 hh->hh_type = protocol;
                 atomic_set(&hh->hh_refcnt, 0);
                 hh->hh_next = NULL;