Message-ID: <1354916502.9124.18.camel@jlt4.sipsolutions.net> (sfid-20121207_224129_500056_6617D80D)
Subject: Re: [RFC PATCH] af_packet: don't to defrag shared skb
From: Johannes Berg <johannes@sipsolutions.net>
To: David Miller <davem@davemloft.net>
Cc: eric@regit.org, netdev@vger.kernel.org,
	linux-wireless@vger.kernel.org, linville@tuxdriver.com
Date: Fri, 07 Dec 2012 22:41:42 +0100
In-Reply-To: <1354915824.9124.11.camel@jlt4.sipsolutions.net> (sfid-20121207_223020_561049_DB965D43)
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	 <20121207.153134.25835204617509469.davem@davemloft.net>
	 <1354915824.9124.11.camel@jlt4.sipsolutions.net>
	 (sfid-20121207_223020_561049_DB965D43)
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On Fri, 2012-12-07 at 22:30 +0100, Johannes Berg wrote:

> The only other theory I can come up with right now is that the skb_get()
> happens in deliver_skb via __netif_receive_skb. Keeping in mind that
> wpa_supplicant might have another packet socket open for authentication
> packets, that seems like a possibility. I'll test it once I figure out
> how to do this "defrag" option you speak of :)

Hmm now I'm venturing into the unknown (for me) and realm of
speculation...

wpa_supplicant opens a packet socket for ETH_P_EAPOL, which indirectly
eventually calls dev_add_pack(). But if you do the same for another
socket, you'll get the same again, and then deliver_skb() will deliver
only a refcounted packet to the prot_hook->func().

This seems like it could very well cause the problem?

johannes