From: Eric Dumazet <eric.dumazet@gmail.com>
To: Shaohua Li <shaohua.li@intel.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"cl@linux.com" <cl@linux.com>, "tj@kernel.org" <tj@kernel.org>
Subject: Re: [PATCH 3/4]percpu_counter: fix code for 32bit systems
Date: Wed, 13 Apr 2011 04:32:07 +0200 [thread overview]
Message-ID: <1302661927.2811.18.camel@edumazet-laptop> (raw)
In-Reply-To: <1302656465.3981.133.camel@sli10-conroe>
Le mercredi 13 avril 2011 à 09:01 +0800, Shaohua Li a écrit :
> On Tue, 2011-04-12 at 17:03 +0800, Eric Dumazet wrote:
> >
> > Hmm... did you test this with LOCKDEP on ?
> >
> > You add a possible deadlock here.
> >
> > Hint : Some percpu_counter are used from irq context.
> there are some places we didn't disable interrupt, for example
> percpu_counter_add. So the API isn't irq safe to me.
>
So what ? Callers must disable IRQ before calling percpu_counter_add(),
and they actually do in network stack. Please check again,
tcp_sockets_allocated for example.
> > This interface assumes caller take the appropriate locking.
> no comments say this, and some places we don't hold locking.
> for example, meminfo_proc_show.
>
This doesnt answer my question about LOCKDEP ;)
Just fix the few callers that might need a fix, since this is the only
way to deal with potential problems without adding performance penalty
(for stable trees)
next prev parent reply other threads:[~2011-04-13 2:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-12 8:04 Shaohua Li
2011-04-12 9:03 ` Eric Dumazet
2011-04-13 1:01 ` Shaohua Li
2011-04-13 2:32 ` Eric Dumazet [this message]
2011-04-13 2:41 ` Shaohua Li
2011-04-13 2:47 ` Eric Dumazet
2011-04-13 3:03 ` Shaohua Li
2011-04-13 3:50 ` tj
2011-04-13 4:37 ` Shaohua Li
2011-04-13 3:53 ` Eric Dumazet
2011-04-13 4:00 ` tj
2011-04-12 19:02 ` Tejun Heo
2011-04-13 1:05 ` Shaohua Li
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