driver-core: skip uevent generation when nobody is listening

Most network namespaces unlikely have listeners to uevents, and should
benefit from skipping all the string copies.

Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index ad72a03ce5e9..e66e9b632617 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -259,6 +259,9 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
                 struct sk_buff *skb;
                 size_t len;
 
+                if (!netlink_has_listeners(uevent_sock, 1))
+                        continue;
+
                 /* allocate message with the maximum possible size */
                 len = strlen(action_string) + strlen(devpath) + 2;
                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);