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>

1 files changed, 12 insertions, 10 deletions

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index a73176eaa57d..818ef9fdab3c 100644
--- 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: