[<prev] [next>] [day] [month] [year] [list]
Message-ID: <20250904165919.3362000-1-rrobaina@redhat.com>
Date: Thu, 4 Sep 2025 13:59:19 -0300
From: Ricardo Robaina <rrobaina@...hat.com>
To: audit@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: paul@...l-moore.com,
eparis@...hat.com,
Ricardo Robaina <rrobaina@...hat.com>
Subject: [PATCH v1] audit: merge loops in __audit_inode_child()
Whenever there's audit context, __audit_inode_child() gets called
numerous times, which can lead to high latency in scenarios that
create too many sysfs/debugfs entries at once, for instance, upon
device_add_disk() invocation.
# uname -r
6.17.0-rc3+
# auditctl -a always,exit -F path=/tmp -k foo
# time insmod loop max_loop=1000
real 0m42.753s
user 0m0.000s
sys 0m42.494s
# perf record -a insmod loop max_loop=1000
# perf report --stdio |grep __audit_inode_child
37.95% insmod [kernel.kallsyms] [k] __audit_inode_child
__audit_inode_child() searches for both the parent and the child
in two different loops that iterate over the same list. This
process can be optimized by merging these into a single loop,
without changing the function behavior or affecting the code's
readability.
This patch merges the two loops that walk through the list
context->names_list into a single loop. This optimization resulted
in around 54% performance enhancement for the benchmark.
# uname -r
6.17.0-rc3+-enhanced
# auditctl -a always,exit -F path=/tmp -k foo
# time insmod loop max_loop=1000
real 0m19.388s
user 0m0.000s
sys 0m19.149s
Signed-off-by: Ricardo Robaina <rrobaina@...hat.com>
---
kernel/auditsc.c | 40 ++++++++++++++++++----------------------
1 file changed, 18 insertions(+), 22 deletions(-)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index eb98cd6fe91f..7abfb68687fb 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2437,44 +2437,40 @@ void __audit_inode_child(struct inode *parent,
if (inode)
handle_one(inode);
- /* look for a parent entry first */
list_for_each_entry(n, &context->names_list, list) {
- if (!n->name ||
- (n->type != AUDIT_TYPE_PARENT &&
- n->type != AUDIT_TYPE_UNKNOWN))
+ /* can only match entries that have a name */
+ if (!n->name)
continue;
- if (n->ino == parent->i_ino && n->dev == parent->i_sb->s_dev &&
- !audit_compare_dname_path(dname,
- n->name->name, n->name_len)) {
+ /* look for a parent entry first */
+ if (!found_parent &&
+ (n->type == AUDIT_TYPE_PARENT || n->type == AUDIT_TYPE_UNKNOWN) &&
+ (n->ino == parent->i_ino && n->dev == parent->i_sb->s_dev &&
+ !audit_compare_dname_path(dname, n->name->name, n->name_len))) {
if (n->type == AUDIT_TYPE_UNKNOWN)
n->type = AUDIT_TYPE_PARENT;
found_parent = n;
- break;
}
- }
- cond_resched();
-
- /* is there a matching child entry? */
- list_for_each_entry(n, &context->names_list, list) {
- /* can only match entries that have a name */
- if (!n->name ||
- (n->type != type && n->type != AUDIT_TYPE_UNKNOWN))
- continue;
-
- if (!strcmp(dname->name, n->name->name) ||
- !audit_compare_dname_path(dname, n->name->name,
+ /* is there a matching child entry? */
+ if (!found_child &&
+ (n->type == type || n->type == AUDIT_TYPE_UNKNOWN) &&
+ (!strcmp(dname->name, n->name->name) ||
+ !audit_compare_dname_path(dname, n->name->name,
found_parent ?
found_parent->name_len :
- AUDIT_NAME_FULL)) {
+ AUDIT_NAME_FULL))) {
if (n->type == AUDIT_TYPE_UNKNOWN)
n->type = type;
found_child = n;
- break;
}
+
+ if (found_parent && found_child)
+ break;
}
+ cond_resched();
+
if (!found_parent) {
/* create a new, "anonymous" parent record */
n = audit_alloc_name(context, AUDIT_TYPE_PARENT);
--
2.51.0
Powered by blists - more mailing lists