netdev - Re: [PATCH] net af_key: Fix RCU splat

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Message-Id: <20150823.164821.642841258349384154.davem@davemloft.net>
Date:	Sun, 23 Aug 2015 16:48:21 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	dsa@...ulusnetworks.com
Cc:	steffen.klassert@...unet.com, netdev@...r.kernel.org
Subject: Re: [PATCH] net af_key: Fix RCU splat

From: David Ahern <dsa@...ulusnetworks.com>
Date: Thu, 20 Aug 2015 08:51:40 -0700

> @@ -1670,7 +1670,7 @@ static int pfkey_register(struct sock *sk, struct sk_buff *skb, const struct sad
>  		return -ENOBUFS;
>  	}
>  
> -	pfkey_broadcast(supp_skb, GFP_KERNEL, BROADCAST_REGISTERED, sk, sock_net(sk));
> +	pfkey_broadcast(supp_skb, GFP_ATOMIC, BROADCAST_REGISTERED, sk, sock_net(sk));

As Eric alluded to, the gfp_t argument is totally pointless.

It is used inside of pfkey_broadcast() via calls to pfkey_broadcast_one() inside of
an RCU protected area _CREATED_ by pfkey_broadcast() itself.

Therefore it could never possibly honor a sleeping gfp_t flag, and GFP_ATOMIC must
always be used.

So just get rid of it and use GFP_ATOMIC unconditionally.
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