linux-kernel - Re: [PATCH -tip] x86: hw-breakpoints: Actually flush thread breakpoints in flush

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Message-ID: <20091018062558.GA20535@linux-sh.org>
Date:	Sun, 18 Oct 2009 15:25:58 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	"K.Prasad" <prasad@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Alan Stern <stern@...land.harvard.edu>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH -tip] x86: hw-breakpoints: Actually flush thread breakpoints in flush_thread().

On Sun, Oct 18, 2009 at 01:42:53AM +0200, Frederic Weisbecker wrote:
> On Fri, Oct 09, 2009 at 12:40:04PM +0900, Paul Mundt wrote:
> > On Mon, Oct 05, 2009 at 04:19:55PM +0530, K.Prasad wrote:
> > > On Mon, Oct 05, 2009 at 07:23:06PM +0900, Paul Mundt wrote:
> > > > [ I noticed this whilst hacking up SH support, applies to the current
> > > >   tracing/hw-breakpoints topic branch. ]
> > > > 
> > > > flush_thread() tries to do a TIF_DEBUG check before calling in to
> > > > flush_thread_hw_breakpoint() (which subsequently clears the thread flag),
> > > > but for some reason, the x86 code is manually clearing TIF_DEBUG
> > > > immediately before the test, so this path will never be taken.
> > > > 
> > > > This kills off the erroneous clear_tsk_thread_flag() and lets
> > > > flush_thread_hw_breakpoint() actually get invoked.
> > > > 
> > > 
> > > Yes, this is wrong and we missed it. Thanks for fixing!
> > > 
> > > > Presumably folks were getting lucky with testing and the
> > > > free_thread_info() -> free_thread_xstate() path was taking care of the
> > > > flush there.
> > > > 
> > > > Signed-off-by: Paul Mundt <lethal@...ux-sh.org>
> > > 
> > > Acked-by: K.Prasad <prasad@...ux.vnet.ibm.com>
> > > 
> > > 
> > Ingo, are you planning on picking this up? Or is there a hw-breakpoints
> > tree somewhere outside of -tip that I'm unaware of?
> 
> 
> I'm picking it.
> Thanks.
> 
Thanks. If you're setting up a tree somewhere can you let me know where
it will be hosted? I'm pretty much done with the SH support for the
existing topic branch in -tip, but if it's being reworked, then I'd like
to get my changes reworked and integrated as soon as possible.
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