linux-kernel - Re: NOHZ: local_softirq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20091012.033246.56701176.davem@davemloft.net>
Date:	Mon, 12 Oct 2009 03:32:46 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	tilman@...p.cc
Cc:	johannes@...solutions.net, hidave.darkstar@...il.com,
	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	linux-wireless@...r.kernel.org, linux-ppp@...r.kernel.org,
	netdev@...r.kernel.org, paulus@...ba.org
Subject: Re: NOHZ: local_softirq_pending 08

From: Tilman Schmidt <tilman@...p.cc>
Date: Mon, 12 Oct 2009 10:28:56 +0200

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> [CCing PPP people]
> 
> Am 11.10.2009 13:40 schrieb Johannes Berg:
>> On Sun, 2009-10-11 at 13:18 +0200, Tilman Schmidt wrote:
>> 
>>> Can you explain a bit more what that message is about?
>>> I am encountering it in a completely different context
>>> (PPP over ISDN) [...]
>> 
>> Basically, calling netif_rx() with softirqs enabled.
> 
> AFAICS that would have to be the netif_rx() call in
> ppp_receive_nonmp_frame() [drivers/net/ppp_generic.c#L1791],
> called (via others) from the tasklet work function
> ppp_sync_process() [drivers/net/ppp_synctty.c#L545].
> Should that be changed to the
> "if (in_interrupt()) netif_rx(skb) else netif_rx_ni(skb)"
> stanza from the linux.kernel.wireless.general thread then?

The PPP receive paths in ppp_generic.c do a local_bh_disable()/
local_bh_enable() around packet receiving (via ppp_recv_lock()/
ppp_recv_unlock() in ppp_do_recv).

So at least that part is perfectly fine.

ppp_input(), as called from ppp_sync_process(), also disables BH's
around ppp_do_recv() calls (via read_lock_bh()/read_unlock_bh()).

So that's fine too.

Do you have a bug report or are you just scanning around looking
for trouble? :-)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/