linux-kernel - Re: [PATCH] kgdbts: fix hw_access_break

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Message-ID: <20240814153843.GA168155@aspen.lan>
Date: Wed, 14 Aug 2024 16:38:43 +0100
From: Daniel Thompson <daniel.thompson@...aro.org>
To: Doug Anderson <dianders@...omium.org>
Cc: Florian Rommel <mail@...rommel.de>,
	Jason Wessel <jason.wessel@...driver.com>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kgdbts: fix hw_access_break_test

On Mon, Aug 12, 2024 at 01:04:22PM -0700, Doug Anderson wrote:
> Hi,
>
> On Mon, Aug 12, 2024 at 1:55 AM Florian Rommel <mail@...rommel.de> wrote:
> >
> > The test for access watchpoints (hw_access_break_test) was broken
> > (always failed) because the compiler optimized out the write to the
> > static helper variable (hw_break_val2), as it is never read anywhere.
> > This resulted in the target variable (hw_break_val) not being accessed
> > and thus the breakpoint not being triggered.
> >
> > Remove the helper variable (hw_break_val2), and use READ_ONCE to force
> > reading the target variable (hw_break_val).
> >
> > Signed-off-by: Florian Rommel <mail@...rommel.de>
> > ---
> >  drivers/misc/kgdbts.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
>
> Reviewed-by: Douglas Anderson <dianders@...omium.org>

Looks good. I pushed this through kgdbtest and it likes it too. I can
turn one of the XFAILs off (yay).

Acked-by: Daniel Thompson <daniel.thompson@...aro.org>
Tested-by: Daniel Thompson <daniel.thompson@...aro.org>

Arnd/Greg: Are you happy to pick this up or should I take it through the kgdb
tree? FWIW right now there are zero other patches for kgdb this cycle, although
that could change!


Daniel.