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

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Message-ID: <20091005104955.GA14852@in.ibm.com>
Date:	Mon, 5 Oct 2009 16:19:55 +0530
From:	"K.Prasad" <prasad@...ux.vnet.ibm.com>
To:	Paul Mundt <lethal@...ux-sh.org>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH -tip] x86: hw-breakpoints: Actually flush thread
	breakpoints in flush_thread().

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>


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