[IPV4] fib: convert reader/writer to spinlock

Ther is no point in using a more expensive reader/writer lock
for a low contention lock like the fib_info_lock. The only
reader case is in handling route redirects.

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

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 5173800..38bca47 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -49,7 +49,7 @@
 
 #define FSprintk(a...)
 
-static DEFINE_RWLOCK(fib_info_lock);
+static DEFINE_SPINLOCK(fib_info_lock);
 static struct hlist_head *fib_info_hash;
 static struct hlist_head *fib_info_laddrhash;
 static unsigned int fib_hash_size;
@@ -159,7 +159,7 @@ void free_fib_info(struct fib_info *fi)
 
 void fib_release_info(struct fib_info *fi)
 {
-       write_lock_bh(&fib_info_lock);
+       spin_lock_bh(&fib_info_lock);
        if (fi && --fi->fib_treeref == 0) {
                hlist_del(&fi->fib_hash);
                if (fi->fib_prefsrc)
@@ -172,7 +172,7 @@ void fib_release_info(struct fib_info *fi)
                fi->fib_dead = 1;
                fib_info_put(fi);
        }
-       write_unlock_bh(&fib_info_lock);
+       spin_unlock_bh(&fib_info_lock);
 }
 
 static __inline__ int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
@@ -254,7 +254,7 @@ int ip_fib_check_default(u32 gw, struct net_device *dev)
        struct fib_nh *nh;
        unsigned int hash;
 
-       read_lock(&fib_info_lock);
+       spin_lock(&fib_info_lock);
 
        hash = fib_devindex_hashfn(dev->ifindex);
        head = &fib_info_devhash[hash];
@@ -262,12 +262,12 @@ int ip_fib_check_default(u32 gw, struct net_device *dev)
                if (nh->nh_dev == dev &&
                    nh->nh_gw == gw &&
                    !(nh->nh_flags&RTNH_F_DEAD)) {
-                       read_unlock(&fib_info_lock);
+                       spin_unlock(&fib_info_lock);
                        return 0;
                }
        }
 
-       read_unlock(&fib_info_lock);
+       spin_unlock(&fib_info_lock);
 
        return -1;
 }
@@ -598,7 +598,7 @@ static void fib_hash_move(struct hlist_head *new_info_hash,
        unsigned int old_size = fib_hash_size;
        unsigned int i, bytes;
 
-       write_lock_bh(&fib_info_lock);
+       spin_lock_bh(&fib_info_lock);
        old_info_hash = fib_info_hash;
        old_laddrhash = fib_info_laddrhash;
        fib_hash_size = new_size;
@@ -639,7 +639,7 @@ static void fib_hash_move(struct hlist_head *new_info_hash,
        }
        fib_info_laddrhash = new_laddrhash;
 
-       write_unlock_bh(&fib_info_lock);
+       spin_unlock_bh(&fib_info_lock);
 
        bytes = old_size * sizeof(struct hlist_head *);
        fib_hash_free(old_info_hash, bytes);
@@ -820,7 +820,7 @@ link_it:
 
        fi->fib_treeref++;
        atomic_inc(&fi->fib_clntref);
-       write_lock_bh(&fib_info_lock);
+       spin_lock_bh(&fib_info_lock);
        hlist_add_head(&fi->fib_hash,
                       &fib_info_hash[fib_info_hashfn(fi)]);
        if (fi->fib_prefsrc) {
@@ -839,7 +839,7 @@ link_it:
                head = &fib_info_devhash[hash];
                hlist_add_head(&nh->nh_hash, head);
        } endfor_nexthops(fi)
-       write_unlock_bh(&fib_info_lock);
+       spin_unlock_bh(&fib_info_lock);
        return fi;
 
 err_inval: