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From: kbuild test robot <lkp@intel.com>
To: kbuild-all@lists.01.org
Subject: Re: [PATCH v2 bpf] bpf: Do not grab the bucket spinlock by default on htab batch ops
Date: Thu, 20 Feb 2020 10:25:30 +0800	[thread overview]
Message-ID: <202002201058.aPiTHFA1%lkp@intel.com> (raw)
In-Reply-To: <20200218172552.215077-1-brianvv@google.com>

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Hi Brian,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on bpf/master]
[also build test WARNING on bpf-next/master v5.6-rc2 next-20200219]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Brian-Vazquez/bpf-Do-not-grab-the-bucket-spinlock-by-default-on-htab-batch-ops/20200220-073319
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
config: s390-defconfig (attached as .config)
compiler: s390-linux-gcc (GCC) 7.5.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.5.0 make.cross ARCH=s390 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   In file included from include/linux/irqflags.h:16:0,
                    from arch/s390/include/asm/processor.h:41,
                    from arch/s390/include/asm/thread_info.h:27,
                    from include/linux/thread_info.h:38,
                    from arch/s390/include/asm/preempt.h:6,
                    from include/linux/preempt.h:78,
                    from include/linux/spinlock.h:51,
                    from include/linux/seqlock.h:36,
                    from include/linux/time.h:6,
                    from include/linux/ktime.h:24,
                    from include/linux/timer.h:6,
                    from include/linux/workqueue.h:9,
                    from include/linux/bpf.h:9,
                    from kernel//bpf/hashtab.c:5:
   kernel//bpf/hashtab.c: In function '__htab_map_lookup_and_delete_batch':
>> arch/s390/include/asm/irqflags.h:64:12: warning: 'flags' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (flags & ARCH_IRQ_ENABLED)
               ^
   kernel//bpf/hashtab.c:1262:16: note: 'flags' was declared here
     unsigned long flags;
                   ^~~~~
--
   In file included from include/linux/irqflags.h:16:0,
                    from arch/s390/include/asm/processor.h:41,
                    from arch/s390/include/asm/thread_info.h:27,
                    from include/linux/thread_info.h:38,
                    from arch/s390/include/asm/preempt.h:6,
                    from include/linux/preempt.h:78,
                    from include/linux/spinlock.h:51,
                    from include/linux/seqlock.h:36,
                    from include/linux/time.h:6,
                    from include/linux/ktime.h:24,
                    from include/linux/timer.h:6,
                    from include/linux/workqueue.h:9,
                    from include/linux/bpf.h:9,
                    from kernel/bpf/hashtab.c:5:
   kernel/bpf/hashtab.c: In function '__htab_map_lookup_and_delete_batch':
>> arch/s390/include/asm/irqflags.h:64:12: warning: 'flags' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (flags & ARCH_IRQ_ENABLED)
               ^
   kernel/bpf/hashtab.c:1262:16: note: 'flags' was declared here
     unsigned long flags;
                   ^~~~~

vim +/flags +64 arch/s390/include/asm/irqflags.h

1f194a4c393103 include/asm-s390/irqflags.h      Heiko Carstens        2006-07-03  59  
204ee2c5643199 arch/s390/include/asm/irqflags.h Christian Borntraeger 2016-01-11  60  /* This only restores external and I/O interrupt state */
f433c4aec9999d arch/s390/include/asm/irqflags.h Steven Rostedt        2011-07-24  61  static inline notrace void arch_local_irq_restore(unsigned long flags)
df9ee29270c11d arch/s390/include/asm/irqflags.h David Howells         2010-10-07  62  {
204ee2c5643199 arch/s390/include/asm/irqflags.h Christian Borntraeger 2016-01-11  63  	/* only disabled->disabled and disabled->enabled is valid */
204ee2c5643199 arch/s390/include/asm/irqflags.h Christian Borntraeger 2016-01-11 @64  	if (flags & ARCH_IRQ_ENABLED)
204ee2c5643199 arch/s390/include/asm/irqflags.h Christian Borntraeger 2016-01-11  65  		arch_local_irq_enable();
df9ee29270c11d arch/s390/include/asm/irqflags.h David Howells         2010-10-07  66  }
df9ee29270c11d arch/s390/include/asm/irqflags.h David Howells         2010-10-07  67  

:::::: The code at line 64 was first introduced by commit
:::::: 204ee2c5643199a25181ec04ea645d00709c2a5a s390/irqflags: optimize irq restore

:::::: TO: Christian Borntraeger <borntraeger@de.ibm.com>
:::::: CC: Martin Schwidefsky <schwidefsky@de.ibm.com>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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  parent reply	other threads:[~2020-02-20  2:25 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 17:25 [PATCH v2 bpf] bpf: Do not grab the bucket spinlock by default on htab batch ops Brian Vazquez
2020-02-18 21:23 ` Yonghong Song
2020-02-19 23:12   ` Alexei Starovoitov
2020-02-20  2:25 ` kbuild test robot [this message]
2020-02-20  5:29 ` kbuild test robot

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