Date: Wed, 22 Jun 2011 20:24:24 +0530
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
        Linux-mm <linux-mm@kvack.org>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Hugh Dickins <hughd@google.com>, Christoph Hellwig <hch@infradead.org>,
        Andi Kleen <andi@firstfloor.org>, Thomas Gleixner <tglx@linutronix.de>,
        Jonathan Corbet <corbet@lwn.net>, Oleg Nesterov <oleg@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jim Keniston <jkenisto@linux.vnet.ibm.com>,
        Roland McGrath <roland@hack.frob.com>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 3.0-rc2-tip 14/22] 14: x86: uprobes exception
 notifier for x86.
Message-ID: <20110622145424.GG16471@linux.vnet.ibm.com>
Reply-To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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* Peter Zijlstra <peterz@infradead.org> [2011-06-21 15:32:47]:

> On Tue, 2011-06-21 at 15:31 +0200, Peter Zijlstra wrote:
> > On Tue, 2011-06-07 at 18:31 +0530, Srikar Dronamraju wrote:
> > > @@ -844,6 +845,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
> > >         if (thread_info_flags & _TIF_SIGPENDING)
> > >                 do_signal(regs);
> > >  
> > > +       if (thread_info_flags & _TIF_UPROBE) {
> > > +               clear_thread_flag(TIF_UPROBE);
> > > +#ifdef CONFIG_X86_32
> > > +               /*
> > > +                * On x86_32, do_notify_resume() gets called with
> > > +                * interrupts disabled. Hence enable interrupts if they
> > > +                * are still disabled.
> > > +                */
> > > +               local_irq_enable();
> > > +#endif
> > > +               uprobe_notify_resume(regs);
> > > +       } 
> > 
> > Would it make sense to do TIF_UPROBE before TIF_SIGPENDING? That way
> > when uprobe decides it ought to have send a signal we don't have to do
> > another loop through all this.
> 

Okay, 

> 
> Also, it might be good to unify x86_86 and i386 on the interrupt thing,
> instead of propagating this difference (unless of course there's a good
> reason they're different, but I really don't know this code well).

I am not sure if this has changed lately. So I will try removing the
local_irq_enable. 

Oleg, Roland, do you know why do_notify_resume() gets called with
interrupts disabled on i386? 

-- 
Thanks and Regards
Srikar
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