linux-kernel - Re: [PATCH 8/9] KVM: Adjust seven checks for null pointers

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Date:   Mon, 23 Jan 2017 04:32:10 +0800
From:   kbuild test robot <lkp@...el.com>
To:     SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:     kbuild-all@...org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 8/9] KVM: Adjust seven checks for null pointers

Hi Markus,

[auto build test WARNING on kvm/linux-next]
[also build test WARNING on v4.10-rc4 next-20170120]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/SF-Markus-Elfring/KVM-Fine-tuning-for-several-function-implementations/20170123-022323
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: x86_64-allyesdebian (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function 'kvm_make_all_cpus_request':
>> arch/x86/kvm/../../../virt/kvm/kvm_main.c:187:7: warning: the address of 'cpus' will always evaluate as 'true' [-Waddress]
      if (cpus && cpu != -1 && cpu != me &&
          ^~~~

vim +187 arch/x86/kvm/../../../virt/kvm/kvm_main.c

   171	{
   172		int i, cpu, me;
   173		cpumask_var_t cpus;
   174		bool called = true;
   175		struct kvm_vcpu *vcpu;
   176	
   177		zalloc_cpumask_var(&cpus, GFP_ATOMIC);
   178	
   179		me = get_cpu();
   180		kvm_for_each_vcpu(i, vcpu, kvm) {
   181			kvm_make_request(req, vcpu);
   182			cpu = vcpu->cpu;
   183	
   184			/* Set ->requests bit before we read ->mode. */
   185			smp_mb__after_atomic();
   186	
 > 187			if (cpus && cpu != -1 && cpu != me &&
   188			      kvm_vcpu_exiting_guest_mode(vcpu) != OUTSIDE_GUEST_MODE)
   189				cpumask_set_cpu(cpu, cpus);
   190		}
   191		if (unlikely(cpus == NULL))
   192			smp_call_function_many(cpu_online_mask, ack_flush, NULL, 1);
   193		else if (!cpumask_empty(cpus))
   194			smp_call_function_many(cpus, ack_flush, NULL, 1);
   195		else

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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