[AF_UNIX]: Use spinlock for unix_table_lock

This lock is actually taken mostly as a writer,
so using a rwlock actually just makes performance
worse especially on chips like the Intel P4.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index 6ffc64e..411802b 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -182,7 +182,7 @@
 	if (down_trylock(&unix_gc_sem))
 		return;
 
-	read_lock(&unix_table_lock);
+	spin_lock(&unix_table_lock);
 
 	forall_unix_sockets(i, s)
 	{
@@ -301,7 +301,7 @@
 		}
 		u->gc_tree = GC_ORPHAN;
 	}
-	read_unlock(&unix_table_lock);
+	spin_unlock(&unix_table_lock);
 
 	/*
 	 *	Here we are. Hitlist is filled. Die.