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
| ||
|
Date: Tue, 27 Apr 2010 13:58:30 -0400 From: Miles Lane <miles.lane@...il.com> To: paulmck@...ux.vnet.ibm.com Cc: "Eric W. Biederman" <ebiederm@...ssion.com>, Vivek Goyal <vgoyal@...hat.com>, Eric Paris <eparis@...hat.com>, Lai Jiangshan <laijs@...fujitsu.com>, Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>, LKML <linux-kernel@...r.kernel.org>, nauman@...gle.com, eric.dumazet@...il.com, netdev@...r.kernel.org, Jens Axboe <jens.axboe@...cle.com>, Gui Jianfeng <guijianfeng@...fujitsu.com>, Li Zefan <lizf@...fujitsu.com>, Johannes Berg <johannes@...solutions.net> Subject: Re: [PATCH] RCU: don't turn off lockdep when find suspicious rcu_dereference_check() usage On Tue, Apr 27, 2010 at 12:22 PM, Paul E. McKenney <paulmck@...ux.vnet.ibm.com> wrote: > On Mon, Apr 26, 2010 at 09:27:44PM -0700, Paul E. McKenney wrote: >> On Mon, Apr 26, 2010 at 11:35:10AM -0700, Eric W. Biederman wrote: >> > "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> writes: >> > >> > > Eric Dumazet traced these down to a commit from Eric Biederman. >> > > >> > > If I don't hear from Eric Biederman in a few days, I will attempt a >> > > patch, but it would be more likely to be correct coming from someone >> > > with a better understanding of the code. ;-) >> > >> > I already replied. >> > >> > http://lkml.org/lkml/2010/4/21/420 >> >> You did indeed!!! This experience is giving me an even better appreciation >> of the maintainers' ability to keep all their patches straight! >> >> I will put together something based on your suggestion. > > How about the following? > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit 85fa42bd568ab99c375f018761ae6345249942cd > Author: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> > Date: Mon Apr 26 21:40:05 2010 -0700 > > net: suppress RCU lockdep false positive in twsk_net() > > Calls to twsk_net() are in some cases protected by reference counting > as an alternative to RCU protection. Cases covered by reference counts > include __inet_twsk_kill(), inet_twsk_free(), inet_twdr_do_twkill_work(), > inet_twdr_twcal_tick(), and tcp_timewait_state_process(). RCU is used > by inet_twsk_purge(). Locking is used by established_get_first() > and established_get_next(). Finally, __inet_twsk_hashdance() is an > initialization case. > > It appears to be non-trivial to locate the appropriate locks and > reference counts from within twsk_net(), so used rcu_dereference_raw(). > > Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> > > diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h > index 79f67ea..a066fdd 100644 > --- a/include/net/inet_timewait_sock.h > +++ b/include/net/inet_timewait_sock.h > @@ -224,7 +224,9 @@ static inline > struct net *twsk_net(const struct inet_timewait_sock *twsk) > { > #ifdef CONFIG_NET_NS > - return rcu_dereference(twsk->tw_net); > + return rcu_dereference_raw(twsk->tw_net); /* protected by locking, */ > + /* reference counting, */ > + /* initialization, or RCU. */ > #else > return &init_net; > #endif > Worked for me. Thanks! Miles -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists