Re: [PATCH v2] tools/power turbostat: Fix RAPL summary collection on AMD processors

From: Chen Yu <yu.c.chen@intel.com>
To: Borislav Petkov <bp@suse.de>
Cc: Calvin Walton <calvin.walton@kepstin.ca>,
	Terry Bowman <terry.bowman@amd.com>,
	lenb@kernel.org, linux-pm@vger.kernel.org,
	linux-kernel@vger.kernel.org, wei.huang2@amd.com, aros@gmx.com,
	rui.zhang@intel.com
Subject: Re: [PATCH v2] tools/power turbostat: Fix RAPL summary collection on AMD processors
Date: Fri, 23 Apr 2021 21:34:30 +0800	[thread overview]
Message-ID: <20210423133430.GA426650@chenyu-desktop> (raw)
In-Reply-To: <20210423121934.GC24710@zn.tnic>

Hi Boris,
On Fri, Apr 23, 2021 at 02:19:34PM +0200, Borislav Petkov wrote:
> On Fri, Apr 23, 2021 at 08:16:07PM +0800, Chen Yu wrote:
> > From b2e63fe4f02e17289414b4f61237da822df115fb Mon Sep 17 00:00:00 2001
> > From: Calvin Walton <calvin.walton@kepstin.ca>
> > Date: Fri, 23 Apr 2021 17:32:13 +0800
> > Subject: [PATCH 3/5] tools/power turbostat: Fix offset overflow issue in index
> >  converting
> > 
> > The idx_to_offset() function returns type int (32-bit signed), but
> > MSR_PKG_ENERGY_STAT is greater than INT_MAX (or rather, would be
> > interpreted as a negative number). The end result is that it hits
> > the if (offset < 0) check in update_msr_sum() resulting in the timer
> > callback for updating the stat in the background when long durations
> > are used to not happen. The similar issue exists in offset_to_idx()
> > and update_msr_sum().
> > 
> > This patch fixes this issue by converting the 'int' type to 'off_t'
> > accordingly.
> > 
> > Fixes: 9972d5d84d76 ("tools/power turbostat: Enable accumulate RAPL display")
> > Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> 
> This patch's authorship is weird: it says From: Calvin but doesn't have
> his SOB here - only yours.
>
I see, I'll add Calvin's SOB here. Previously I thought the 'From' field might
be enough to indicate the Author, but it seems to not be the case.
> > ---
> >  tools/power/x86/turbostat/turbostat.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
> > index a211264b57fd..77557122b292 100644
> > --- a/tools/power/x86/turbostat/turbostat.c
> > +++ b/tools/power/x86/turbostat/turbostat.c
> > @@ -296,9 +296,9 @@ struct msr_sum_array {
> >  /* The percpu MSR sum array.*/
> >  struct msr_sum_array *per_cpu_msr_sum;
> >  
> > -int idx_to_offset(int idx)
> > +off_t idx_to_offset(int idx)
> 
> And this is silly. MSRs are unsigned int. Fullstop.
> 
> So that function should either return u32 or unsigned int or so.
> 
Got it. The off_t was derived from old code in this file from get_msr() and alike,
let me convert this return value to unsigned int.

thanks,
Chenyu
> Thx.
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg