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Date: Wed, 29 Oct 2014 09:29:55 -0700 From: Cong Wang <xiyou.wangcong@...il.com> To: Peter Zijlstra <peterz@...radead.org> Cc: Fengguang Wu <fengguang.wu@...el.com>, LKP <lkp@...org>, LKML <linux-kernel@...r.kernel.org>, "oleg@...hat.com" <oleg@...hat.com>, "Eric W. Biederman" <ebiederm@...ssion.com>, David Miller <davem@...emloft.net>, Linux Kernel Network Developers <netdev@...r.kernel.org> Subject: Re: [PATCH] netdev: Fix sleeping inside wait event (Adding netdev@...) On Wed, Oct 29, 2014 at 9:16 AM, Peter Zijlstra <peterz@...radead.org> wrote: > > Dave, this relies on bits currently in tip/sched/core, if you're ok I'll > merge it through that tree. > > --- > Subject: netdev: Fix sleeping inside wait event > From: Peter Zijlstra <peterz@...radead.org> > Date: Wed Oct 29 17:04:56 CET 2014 > > rtnl_lock_unregistering() takes rtnl_lock() -- a mutex -- inside a > wait loop. The wait loop relies on current->state to function, but so > does mutex_lock(), nesting them makes for the inner to destroy the > outer state. > While you are on it, please fix rtnl_lock_unregistering_all() too? Thanks! > Fix this using the new wait_woken() bits. > > Cc: Oleg Nesterov <oleg@...hat.com> > Cc: Eric Biederman <ebiederm@...ssion.com> > Cc: David Miller <davem@...emloft.net> > Reported-by: Fengguang Wu <fengguang.wu@...el.com> > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org> > --- > net/core/dev.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -7196,11 +7196,10 @@ static void __net_exit rtnl_lock_unregis > */ > struct net *net; > bool unregistering; > - DEFINE_WAIT(wait); > + DEFINE_WAIT_FUNC(wait, woken_wake_function); > > + add_wait_queue(&netdev_unregistering_wq, &wait); > for (;;) { > - prepare_to_wait(&netdev_unregistering_wq, &wait, > - TASK_UNINTERRUPTIBLE); > unregistering = false; > rtnl_lock(); > list_for_each_entry(net, net_list, exit_list) { > @@ -7212,9 +7211,10 @@ static void __net_exit rtnl_lock_unregis > if (!unregistering) > break; > __rtnl_unlock(); > - schedule(); > + > + wait_woken(&wait, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); > } > - finish_wait(&netdev_unregistering_wq, &wait); > + remove_wait_queue(&netdev_unregistering_wq, &wait); > } > > static void __net_exit default_device_exit_batch(struct list_head *net_list) > -- > 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/ -- 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
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