netdev - Re: [PATCH net-next,v2] ipv6: Add rate limit mask for ICMPv6 messages

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Message-Id: <20190417.104647.29599416293735161.davem@davemloft.net>
Date:   Wed, 17 Apr 2019 10:46:47 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     ssuryaextr@...il.com
Cc:     netdev@...r.kernel.org, brouer@...hat.com
Subject: Re: [PATCH net-next,v2] ipv6: Add rate limit mask for ICMPv6
 messages

From: Stephen Suryaputra <ssuryaextr@...il.com>
Date: Mon, 15 Apr 2019 20:31:57 -0400

> @@ -850,6 +850,14 @@ static int __net_init inet6_net_init(struct net *net)
>  	net->ipv6.sysctl.icmpv6_echo_ignore_all = 0;
>  	net->ipv6.sysctl.icmpv6_echo_ignore_multicast = 0;
>  	net->ipv6.sysctl.icmpv6_echo_ignore_anycast = 0;
> +	net->ipv6.sysctl.icmpv6_ratemask = kzalloc(ICMPV6_MSG_MAX + 1, GFP_KERNEL);
> +	if (net->ipv6.sysctl.icmpv6_ratemask) {
> +		/* By default, rate limit error messages.
> +		 * Except for pmtu discovery, it would break it.
> +		 */
> +		bitmap_set(net->ipv6.sysctl.icmpv6_ratemask, 0, ICMPV6_ERRMSG_MAX + 1);
> +		bitmap_clear(net->ipv6.sysctl.icmpv6_ratemask, ICMPV6_PKT_TOOBIG, 1);
> +	}

You're allocating space for ICMPV6_MSG_MAX + 1 "bytes" but you only need enough space
for that many "bits".  Which is just four 64-bit words, so you can probably inline it.