We can build one skb and let it be cloned in netlink.
This is much faster, and use less memory (all clones will
share the same skb->head)
Tested:
time perf record (for f in `seq 1 3000` ; do ip netns add tast$f; done)
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 4.110 MB perf.data (~179584 samples) ]
real 0m24.227s # instead of 0m52.554s
user 0m0.329s
sys 0m23.753s # instead of 0m51.375s
14.77% ip [kernel.kallsyms] [k] __ip6addrlbl_add
14.56% ip [kernel.kallsyms] [k] netlink_broadcast_filtered
11.65% ip [kernel.kallsyms] [k] netlink_has_listeners
6.19% ip [kernel.kallsyms] [k] _raw_spin_lock_irqsave
5.66% ip [kernel.kallsyms] [k] kobject_uevent_env
4.97% ip [kernel.kallsyms] [k] memset_erms
4.67% ip [kernel.kallsyms] [k] refcount_sub_and_test
4.41% ip [kernel.kallsyms] [k] _raw_read_lock
3.59% ip [kernel.kallsyms] [k] refcount_inc_not_zero
3.13% ip [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
1.55% ip [kernel.kallsyms] [k] __wake_up
1.20% ip [kernel.kallsyms] [k] strlen
1.03% ip [kernel.kallsyms] [k] __wake_up_common
0.93% ip [kernel.kallsyms] [k] consume_skb
0.92% ip [kernel.kallsyms] [k] netlink_trim
0.87% ip [kernel.kallsyms] [k] insert_header
0.63% ip [kernel.kallsyms] [k] unmap_page_range
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
lib/kobject_uevent.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index
78b2a7e378c0deda3b32b1178d7f44203702c3f2..147db91c10d06485868ff56626a5a9b073a8a846
100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -301,23 +301,26 @@ static int kobject_uevent_net_broadcast(struct kobject
*kobj,
{
int retval = 0;
#if defined(CONFIG_NET)
+ struct sk_buff *skb = NULL;
struct uevent_sock *ue_sk;
/* send netlink message */
list_for_each_entry(ue_sk, &uevent_sock_list, list) {
struct sock *uevent_sock = ue_sk->sk;
- 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);
- if (skb) {
+ if (!skb) {
+ /* allocate message with the maximum possible size */
+ size_t len = strlen(action_string) + strlen(devpath) +
2;
char *scratch;
+ retval = -ENOMEM;
+ skb = alloc_skb(len + env->buflen, GFP_KERNEL);
+ if (!skb)
+ continue;
+
/* add header */
scratch = skb_put(skb, len);
sprintf(scratch, "%s@%s", action_string, devpath);
@@ -325,16 +328,17 @@ static int kobject_uevent_net_broadcast(struct kobject
*kobj,
skb_put_data(skb, env->buf, env->buflen);
NETLINK_CB(skb).dst_group = 1;
- retval = netlink_broadcast_filtered(uevent_sock, skb,
- 0, 1, GFP_KERNEL,
- kobj_bcast_filter,
- kobj);
- /* ENOBUFS should be handled in userspace */
- if (retval == -ENOBUFS || retval == -ESRCH)
- retval = 0;
- } else
- retval = -ENOMEM;
+ }
+
+ retval = netlink_broadcast_filtered(uevent_sock, skb_get(skb),
+ 0, 1, GFP_KERNEL,
+ kobj_bcast_filter,
+ kobj);
+ /* ENOBUFS should be handled in userspace */
+ if (retval == -ENOBUFS || retval == -ESRCH)
+ retval = 0;
}
+ consume_skb(skb);
#endif
return retval;
}
--
2.14.1.690.gbb1197296e-goog
