kobject: copy env blob in one go

No need to iterate over strings, just copy in one efficient memcpy() call.

Tested:
time perf record "(for f in `seq 1 3000` ; do ip netns add tast$f; done)"
[ perf record: Woken up 10 times to write data ]
[ perf record: Captured and wrote 8.224 MB perf.data (~359301 samples) ]

real    0m52.554s  # instead of 1m7.492s
user    0m0.309s
sys 0m51.375s # instead of 1m6.875s

     9.88%       ip  [kernel.kallsyms]  [k] netlink_broadcast_filtered
     8.86%       ip  [kernel.kallsyms]  [k] string
     7.37%       ip  [kernel.kallsyms]  [k] __ip6addrlbl_add
     5.68%       ip  [kernel.kallsyms]  [k] netlink_has_listeners
     5.52%       ip  [kernel.kallsyms]  [k] memcpy_erms
     4.76%       ip  [kernel.kallsyms]  [k] __alloc_skb
     4.54%       ip  [kernel.kallsyms]  [k] vsnprintf
     3.94%       ip  [kernel.kallsyms]  [k] format_decode
     3.80%       ip  [kernel.kallsyms]  [k] kmem_cache_alloc_node_trace
     3.71%       ip  [kernel.kallsyms]  [k] kmem_cache_alloc_node
     3.66%       ip  [kernel.kallsyms]  [k] kobject_uevent_env
     3.38%       ip  [kernel.kallsyms]  [k] strlen
     2.65%       ip  [kernel.kallsyms]  [k] _raw_spin_lock_irqsave
     2.20%       ip  [kernel.kallsyms]  [k] kfree
     2.09%       ip  [kernel.kallsyms]  [k] memset_erms
     2.07%       ip  [kernel.kallsyms]  [k] ___cache_free
     1.95%       ip  [kernel.kallsyms]  [k] kmem_cache_free
     1.91%       ip  [kernel.kallsyms]  [k] _raw_read_lock
     1.45%       ip  [kernel.kallsyms]  [k] ksize
     1.25%       ip  [kernel.kallsyms]  [k] _raw_spin_unlock_irqrestore
     1.00%       ip  [kernel.kallsyms]  [k] widen_string

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 4f48cc3..78b2a7e 100644 (file)
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -317,18 +317,12 @@ static int kobject_uevent_net_broadcast(struct kobject *kobj,
                skb = alloc_skb(len + env->buflen, GFP_KERNEL);
                if (skb) {
                        char *scratch;
-                       int i;
 
                        /* add header */
                        scratch = skb_put(skb, len);
                        sprintf(scratch, "%s@%s", action_string, devpath);
 
-                       /* copy keys to our continuous event payload buffer */
-                       for (i = 0; i < env->envp_idx; i++) {
-                               len = strlen(env->envp[i]) + 1;
-                               scratch = skb_put(skb, len);
-                               strcpy(scratch, env->envp[i]);
-                       }
+                       skb_put_data(skb, env->buf, env->buflen);
 
                        NETLINK_CB(skb).dst_group = 1;
                        retval = netlink_broadcast_filtered(uevent_sock, skb,