Re: [PATCH 1/2] x86, msr: add rdmsr_safe_on_cpu_resched() and use it in msr_read()

[kbuild test robot]

Hi Eric,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.16-rc5 next-20180316]
[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/Eric-Dumazet/x86-msr-add-rdmsr_safe_on_cpu_resched-and-use-it-in-msr_read/20180319-001007
config: i386-randconfig-s1-201811 (attached as .config)
compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   arch/x86/kernel/msr.c: In function 'msr_read':
>> arch/x86/kernel/msr.c:63:9: error: implicit declaration of function 'rdmsr_safe_on_cpu_resched' [-Werror=implicit-function-declaration]
      err = rdmsr_safe_on_cpu_resched(cpu, reg, &data[0], &data[1]);
            ^~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors

vim +/rdmsr_safe_on_cpu_resched +63 arch/x86/kernel/msr.c

    48	
    49	static ssize_t msr_read(struct file *file, char __user *buf,
    50				size_t count, loff_t *ppos)
    51	{
    52		u32 __user *tmp = (u32 __user *) buf;
    53		u32 data[2];
    54		u32 reg = *ppos;
    55		int cpu = iminor(file_inode(file));
    56		int err = 0;
    57		ssize_t bytes = 0;
    58	
    59		if (count % 8)
    60			return -EINVAL;	/* Invalid chunk size */
    61	
    62		for (; count; count -= 8) {
  > 63			err = rdmsr_safe_on_cpu_resched(cpu, reg, &data[0], &data[1]);
    64			if (err)
    65				break;
    66			if (copy_to_user(tmp, &data, 8)) {
    67				err = -EFAULT;
    68				break;
    69			}
    70			tmp += 2;
    71			bytes += 8;
    72		}
    73	
    74		return bytes ? bytes : err;
    75	}
    76	

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

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