linux-kernel - [PATCH 4/7] audit: optimize add to parent skipping needless search and consuming parent ref

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Date:	Thu,  2 Oct 2014 22:05:21 -0400
From:	Richard Guy Briggs <rgb@...hat.com>
To:	linux-audit@...hat.com, linux-kernel@...r.kernel.org
Cc:	Richard Guy Briggs <rgb@...hat.com>, eparis@...hat.com,
	sgrubb@...hat.com, aviro@...hat.com, pmoore@...hat.com
Subject: [PATCH 4/7] audit: optimize add to parent skipping needless search and consuming parent ref

When parent has just been created there is no need to search for the parent in
the list.  Add a parameter to skip the search and consume the parent reference
no matter what happens.

Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
---
 kernel/audit_watch.c |   23 +++++++++++++++--------
 1 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index ad9c168..f209448 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -372,15 +372,20 @@ static int audit_get_nd(struct audit_watch *watch, struct path *parent)
 }
 
 /* Associate the given rule with an existing parent.
- * Caller must hold audit_filter_mutex. */
+ * Caller must hold audit_filter_mutex.
+ * Consumes parent reference. */
 static void audit_add_to_parent(struct audit_krule *krule,
-				struct audit_parent *parent)
+				struct audit_parent *parent,
+				int new)
 {
 	struct audit_watch *w, *watch = krule->watch;
 	int watch_found = 0;
 
 	BUG_ON(!mutex_is_locked(&audit_filter_mutex));
 
+	if (new)
+		goto not_found;
+
 	list_for_each_entry(w, &parent->watches, wlist) {
 		if (strcmp(watch->path, w->path))
 			continue;
@@ -396,12 +401,15 @@ static void audit_add_to_parent(struct audit_krule *krule,
 		break;
 	}
 
+not_found:
 	if (!watch_found) {
-		audit_get_parent(parent);
 		watch->parent = parent;
 
 		list_add(&watch->wlist, &parent->watches);
-	}
+	} else
+		/* match get in audit_find_parent or audit_init_parent */
+		audit_put_parent(parent);
+
 	list_add(&krule->rlist, &watch->rules);
 }
 
@@ -413,6 +421,7 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list)
 	struct audit_parent *parent;
 	struct path parent_path;
 	int h, ret = 0;
+	int new = 0;
 
 	mutex_unlock(&audit_filter_mutex);
 
@@ -433,12 +442,10 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list)
 			ret = PTR_ERR(parent);
 			goto error;
 		}
+		new = 1;
 	}
 
-	audit_add_to_parent(krule, parent);
-
-	/* match get in audit_find_parent or audit_init_parent */
-	audit_put_parent(parent);
+	audit_add_to_parent(krule, parent, new);
 
 	h = audit_hash_ino((u32)watch->ino);
 	*list = &audit_inode_hash[h];
-- 
1.7.1

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