selinux: avoid unnecessary avc cache stat hit count

There is no point in counting hits - we can calculate it from the number
of lookups and misses.

This makes the avc statistics a bit smaller, and makes the code
generation better too.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

security/selinux/avc.c

@@ -343,11 +343,10 @@ static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
 	node = avc_search_node(ssid, tsid, tclass);
 
 	if (node)
-		avc_cache_stats_incr(hits);
-	else
-		avc_cache_stats_incr(misses);
-
 		return node;
+
+	avc_cache_stats_incr(misses);
+	return NULL;
 }
 
 static int avc_latest_notif_update(int seqno, int is_insert)
@@ -765,7 +764,7 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid,
 	rcu_read_lock();
 
 	node = avc_lookup(ssid, tsid, tclass);
-	if (!node) {
+	if (unlikely(!node)) {
 		rcu_read_unlock();
 
 		if (in_avd)

security/selinux/include/avc.h

@@ -41,7 +41,6 @@ struct sk_buff;
  */
 struct avc_cache_stats {
 	unsigned int lookups;
-	unsigned int hits;
 	unsigned int misses;
 	unsigned int allocations;
 	unsigned int reclaims;

security/selinux/selinuxfs.c

@@ -1380,10 +1380,14 @@ static int sel_avc_stats_seq_show(struct seq_file *seq, void *v)
 	if (v == SEQ_START_TOKEN)
 		seq_printf(seq, "lookups hits misses allocations reclaims "
 			   "frees\n");
-	else
-		seq_printf(seq, "%u %u %u %u %u %u\n", st->lookups,
-			   st->hits, st->misses, st->allocations,
+	else {
+		unsigned int lookups = st->lookups;
+		unsigned int misses = st->misses;
+		unsigned int hits = lookups - misses;
+		seq_printf(seq, "%u %u %u %u %u %u\n", lookups,
+			   hits, misses, st->allocations,
 			   st->reclaims, st->frees);
+	}
 	return 0;
 }