netdev - Re: [PATCH v2 net-next 0/7] net: speedup netns create/delete time

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Date:   Wed, 13 Dec 2017 13:52:29 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     Tariq Toukan <tariqt@...lanox.com>,
        "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Majd Dibbiny <majd@...lanox.com>,
        Yonatan Cohen <yonatanc@...lanox.com>,
        Eran Ben Elisha <eranbe@...lanox.com>
Subject: Re: [PATCH v2 net-next 0/7] net: speedup netns create/delete time

On Wed, 2017-12-13 at 13:43 -0800, Dmitry Torokhov wrote:
> Hi Eric,
> 
> On Thu, Oct 19, 2017 at 7:11 AM, Eric Dumazet <edumazet@...gle.com> wrote:
> > 
> > On Thu, Oct 19, 2017 at 4:48 AM, Tariq Toukan <tariqt@...lanox.com> wrote:
> > > 
> > > Hi Eric,
> > > 
> > > I just wanted to check if this is solved already, as I don't want to keep an
> > > unnecessary revert patch in our internal branches.
> > > According to my check bug still exists.
> > > 
> > 
> > I will handle this today, thanks for the reminder.
> 
> Did you have a chance to do this? It looks like the original change
> landed on mainline and causes modules to be autoloaded on KOBJ_UNBIND
> again.
> 
> Thanks!

I sent the following to Tariq, and he tested it successfully.

I will submit this formally.

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index c3e84edc47c965d40199b652ba78876cdaa9c70c..0795482b15d5a8f1b65b570a071aa1419cb923d8 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -346,19 +346,25 @@ static int kobject_uevent_net_broadcast(struct kobject *kobj,
 static void zap_modalias_env(struct kobj_uevent_env *env)
 {
 	static const char modalias_prefix[] = "MODALIAS=";
+	size_t offset = 0, len;
 	int i;
 
 	for (i = 0; i < env->envp_idx;) {
+		len = strlen(env->envp[i]) + 1;
 		if (strncmp(env->envp[i], modalias_prefix,
 			    sizeof(modalias_prefix) - 1)) {
 			i++;
+			offset += len;
 			continue;
 		}
 
-		if (i != env->envp_idx - 1)
+		env->buflen -= len;
+		if (i != env->envp_idx - 1) {
+			memmove(env->envp[i], env->envp[i + 1],
+				env->buflen - offset);
 			memmove(&env->envp[i], &env->envp[i + 1],
 				sizeof(env->envp[i]) * env->envp_idx - 1);
-
+		}
 		env->envp_idx--;
 	}
 }