AUDIT: Speed up audit_filter_syscall() for the non-auditable case.

It was showing up fairly high on profiles even when no rules were set.
Make sure the common path stays as fast as possible.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index a73176e..818ef9f 100644 (file)
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -513,20 +513,23 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
                                             struct list_head *list)
 {
        struct audit_entry *e;
-       enum audit_state   state;
-       int                word = AUDIT_WORD(ctx->major);
-       int                bit  = AUDIT_BIT(ctx->major);
+       enum audit_state state;
 
        if (audit_pid && tsk->tgid == audit_pid)
                return AUDIT_DISABLED;
 
        rcu_read_lock();
-       list_for_each_entry_rcu(e, list, list) {
-               if ((e->rule.mask[word] & bit) == bit
-                   && audit_filter_rules(tsk, &e->rule, ctx, &state)) {
-                       rcu_read_unlock();
-                       return state;
-               }
+       if (!list_empty(list)) {
+                   int word = AUDIT_WORD(ctx->major);
+                   int bit  = AUDIT_BIT(ctx->major);
+
+                   list_for_each_entry_rcu(e, list, list) {
+                           if ((e->rule.mask[word] & bit) == bit
+                               && audit_filter_rules(tsk, &e->rule, ctx, &state)) {
+                                   rcu_read_unlock();
+                                   return state;
+                           }
+                   }
        }
        rcu_read_unlock();
        return AUDIT_BUILD_CONTEXT;
@@ -1023,7 +1026,6 @@ void audit_syscall_exit(struct task_struct *tsk, int valid, long return_code)
        } else {
                audit_free_names(context);
                audit_free_aux(context);
-               audit_zero_context(context, context->state);
                tsk->audit_context = context;
        }
  out: