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Date:   Thu, 19 Aug 2021 11:00:31 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     "Chen, Rong A" <rong.a.chen@intel.com>,
        Babu Moger <Babu.Moger@amd.com>,
        Reinette Chatre <reinette.chatre@intel.com>
Cc:     kernel test robot <lkp@intel.com>, x86-ml <x86@kernel.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [tip:x86/urgent] BUILD SUCCESS WITH WARNING
 064855a69003c24bd6b473b367d364e418c57625
Message-ID: <YR4dr079URttZRrg@zn.tnic>
References: <6118d218.4ZZRXYKZCzQSq1Km%lkp@intel.com>
 <YRjTkkpDjaWxEpjb@zn.tnic>
 <ced3f2ab-54b6-95d7-7f5b-b6bb6a299330@intel.com>
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On Thu, Aug 19, 2021 at 02:15:16PM +0800, Chen, Rong A wrote:
> 
> 
> On 8/15/2021 4:42 PM, Borislav Petkov wrote:
> > Hi,
> > 
> > On Sun, Aug 15, 2021 at 04:36:40PM +0800, kernel test robot wrote:
> > > tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/urgent
> > > branch HEAD: 064855a69003c24bd6b473b367d364e418c57625  x86/resctrl: Fix default monitoring groups reporting
> > > 
> > > possible Warning in current branch:
> > > 
> > > arch/x86/kernel/cpu/resctrl/monitor.c:310 __mon_event_count() error: uninitialized symbol 'm'.
> > > arch/x86/kernel/cpu/resctrl/monitor.c:315 __mon_event_count() error: potentially dereferencing uninitialized 'm'.
> > > 
> > > Warning ids grouped by kconfigs:
> > > 
> > > gcc_recent_errors
> > > `-- i386-randconfig-m021-20210812
> > >      |-- arch-x86-kernel-cpu-resctrl-monitor.c-__mon_event_count()-error:potentially-dereferencing-uninitialized-m-.
> > >      `-- arch-x86-kernel-cpu-resctrl-monitor.c-__mon_event_count()-error:uninitialized-symbol-m-.
> > 
> > AFAIR, I had already asked you guys to make those reports more useful
> > as, for example, adding a link to that randconfig above or even
> > attaching it so that a person - not a machine - reading it, can
> > *actually* act upon it.
> > 
> > But that hasn't happened.
> > 
> > Until it happens, I'm going to ignore all those reports from you.
> > 
> 
> Hi Borislav,
> 
> Sorry about it, the actual link is at https://lists.01.org/hyperkitty/list/kbuild@lists.01.org/thread/PZVMY3VJU4QY4HQXHK3MLPQ2KZ5CNAYH/,
> and it's still an internal report that the robot don't know whether it's a
> false positive or not, we'll update the mail contents to avoid
> misunderstanding.

Aha, ok, smatch thinks that m might not be initialized because

064855a69003 ("x86/resctrl: Fix default monitoring groups reporting")

removed the default case:

-       default:
-               /*
-                * Code would never reach here because
-                * an invalid event id would fail the __rmid_read.
-                */
-               return -EINVAL;

I'm guessing that comment which got removed too, explains why that's ok.

Adding folks to Cc.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette