From: "Paul E. McKenney" <paulmck@kernel.org>
To: Rong Chen <rong.a.chen@intel.com>
Cc: kernel test robot <lkp@intel.com>,
clang-built-linux@googlegroups.com, kbuild-all@lists.01.org,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [kbuild-all] Re: kernel/time/clocksource-wdtest.c:47:22: warning: signed shift result (0x27BC86B00) requires 35 bits to represent, but 'long' only has 32 bits
Date: Mon, 5 Jul 2021 08:21:07 -0700 [thread overview]
Message-ID: <20210705152107.GV4397@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <254ab0ec-2c25-29fd-cbe1-eaf2bc135326@intel.com>
On Mon, Jul 05, 2021 at 03:47:09PM +0800, Rong Chen wrote:
>
>
> On 7/5/21 1:43 AM, Paul E. McKenney wrote:
> > On Sun, Jul 04, 2021 at 05:42:36AM +0800, kernel test robot wrote:
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head: 303392fd5c160822bf778270b28ec5ea50cab2b4
> > > commit: 1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff clocksource: Provide kernel module to test clocksource watchdog
> > > date: 11 days ago
> > > config: mips-randconfig-r015-20210702 (attached as .config)
> > > compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 9eb613b2de3163686b1a4bd1160f15ac56a4b083)
> > > reproduce (this is a W=1 build):
> > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> > > chmod +x ~/bin/make.cross
> > > # install mips cross compiling tool for clang build
> > > # apt-get install binutils-mips-linux-gnu
> > > # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff
> > > git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > > git fetch --no-tags linus master
> > > git checkout 1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff
> > > # save the attached .config to linux build tree
> > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips
> > >
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@intel.com>
> > >
> > > All warnings (new ones prefixed by >>):
> > >
> > > > > kernel/time/clocksource-wdtest.c:47:22: warning: signed shift result (0x27BC86B00) requires 35 bits to represent, but 'long' only has 32 bits [-Wshift-overflow]
> > > .mult = TICK_NSEC << JIFFIES_SHIFT, /* details above */
> > > ~~~~~~~~~ ^ ~~~~~~~~~~~~~
> > > 1 warning generated.
> > You have CONFIG_HZ_24=y and this test module assumes HZ > 100, as noted
> > just above the excerpt below:
> >
> > /* Assume HZ > 100. */
> > #define JIFFIES_SHIFT 8
> >
> > So this is expected behavior.
> >
> > Would it help if I gave that comment some teeth, for example, as
> > shown at the end of this email?
>
> Hi Paul,
>
> I have confirmed that the below change can avoid the warning.
Very good, and thank you! May I add your Tested-by?
Thanx, Paul
> Best Regards,
> Rong Chen
>
> >
> > ------------------------------------------------------------------------
> >
> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > index e1856030fa66..8f0ad6e4183c 100644
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -2573,6 +2573,7 @@ config TEST_FPU
> > config TEST_CLOCKSOURCE_WATCHDOG
> > tristate "Test clocksource watchdog in kernel space"
> > depends on CLOCKSOURCE_WATCHDOG
> > + depends on HZ >= 100
> > help
> > Enable this option to create a kernel module that will trigger
> > a test of the clocksource watchdog. This module may be loaded
> > _______________________________________________
> > kbuild-all mailing list -- kbuild-all@lists.01.org
> > To unsubscribe send an email to kbuild-all-leave@lists.01.org
>
next prev parent reply other threads:[~2021-07-05 15:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-03 21:42 kernel/time/clocksource-wdtest.c:47:22: warning: signed shift result (0x27BC86B00) requires 35 bits to represent, but 'long' only has 32 bits kernel test robot
2021-07-04 17:43 ` Paul E. McKenney
2021-07-05 7:47 ` [kbuild-all] " Rong Chen
2021-07-05 15:21 ` Paul E. McKenney [this message]
2021-07-06 0:11 ` Rong Chen
2021-07-06 15:47 ` Paul E. McKenney
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