From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Subject: Re: [PATCH] net: net_secret should not depend on TCP
Date: Tue, 24 Sep 2013 17:13:33 +0200
Message-ID: <20130924151333.GA1527@order.stressinduktion.org>
References: <alpine.DEB.2.02.1309231535030.23896@tomh.mtv.corp.google.com> <1379980991.3165.37.camel@edumazet-glaptop> <20130924023038.GA22393@order.stressinduktion.org> <20130924033505.GB22393@order.stressinduktion.org> <1380001118.3165.41.camel@edumazet-glaptop> <20130924054532.GA24446@order.stressinduktion.org> <1380028797.3165.65.camel@edumazet-glaptop>
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Cc: Tom Herbert <therbert@google.com>, davem@davemloft.net,
	netdev@vger.kernel.org, jesse.brandeburg@intel.com
To: Eric Dumazet <eric.dumazet@gmail.com>
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On Tue, Sep 24, 2013 at 06:19:57AM -0700, Eric Dumazet wrote:
> -void net_secret_init(void)
> +static u32 net_secret[NET_SECRET_SIZE] ____cacheline_aligned;
> +
> +static void net_secret_init(void)
>  {
> -	get_random_bytes(net_secret, sizeof(net_secret));
> +	u32 tmp;
> +	int i;
> +
> +	if (likely(net_secret[0]))
> +		return;
> +
> +	for (i = NET_SECRET_SIZE; i > 0;) {
> +		do {
> +			get_random_bytes(&tmp, sizeof(tmp));
> +		} while (!tmp);

I am afraid we can block here on embedded systems in an atomic section? Is
this actually an issue? It does get called in a spin_lock_h.