linux-kernel - Re: [PATCH] hwmon: coretemp: avoid RDMSR interruptions to isolated CPUs

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Date:   Mon, 26 Dec 2022 09:43:57 -0300
From:   Marcelo Tosatti <mtosatti@...hat.com>
To:     Dan Carpenter <error27@...il.com>
Cc:     oe-kbuild@...ts.linux.dev, Fenghua Yu <fenghua.yu@...el.com>,
        lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        Frederic Weisbecker <frederic@...nel.org>
Subject: Re: [PATCH] hwmon: coretemp: avoid RDMSR interruptions to isolated
 CPUs

On Fri, Dec 23, 2022 at 01:48:14PM +0300, Dan Carpenter wrote:
> Hi Marcelo,
> 
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Marcelo-Tosatti/hwmon-coretemp-avoid-RDMSR-interruptions-to-isolated-CPUs/20221215-204904
> patch link:    https://lore.kernel.org/r/Y5sWMEG0xCl9bgEi%40tpad
> patch subject: [PATCH] hwmon: coretemp: avoid RDMSR interruptions to isolated CPUs
> config: i386-randconfig-m021
> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@...el.com>
> | Reported-by: Dan Carpenter <error27@...il.com>
> 
> smatch warnings:
> drivers/hwmon/coretemp.c:181 show_temp() warn: inconsistent returns '&tdata->update_lock'.
> 
> vim +181 drivers/hwmon/coretemp.c
> 
> 199e0de7f5df31 Durgadoss R     2011-05-20  154  static ssize_t show_temp(struct device *dev,
> 199e0de7f5df31 Durgadoss R     2011-05-20  155  			struct device_attribute *devattr, char *buf)
> 199e0de7f5df31 Durgadoss R     2011-05-20  156  {
> bebe467823c0d8 Rudolf Marek    2007-05-08  157  	u32 eax, edx;
> 199e0de7f5df31 Durgadoss R     2011-05-20  158  	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
> 199e0de7f5df31 Durgadoss R     2011-05-20  159  	struct platform_data *pdata = dev_get_drvdata(dev);
> 199e0de7f5df31 Durgadoss R     2011-05-20  160  	struct temp_data *tdata = pdata->core_data[attr->index];
> 199e0de7f5df31 Durgadoss R     2011-05-20  161  
> 199e0de7f5df31 Durgadoss R     2011-05-20  162  	mutex_lock(&tdata->update_lock);
> bebe467823c0d8 Rudolf Marek    2007-05-08  163  
> 199e0de7f5df31 Durgadoss R     2011-05-20  164  	/* Check whether the time interval has elapsed */
> 199e0de7f5df31 Durgadoss R     2011-05-20  165  	if (!tdata->valid || time_after(jiffies, tdata->last_updated + HZ)) {
> e78264610cd902 Marcelo Tosatti 2022-12-15  166  		if (!housekeeping_cpu(tdata->cpu, HK_TYPE_MISC))
> e78264610cd902 Marcelo Tosatti 2022-12-15  167  			return -EINVAL;
> 
> mutex_unlock(&tdata->update_lock);
> 
> 199e0de7f5df31 Durgadoss R     2011-05-20  168  		rdmsr_on_cpu(tdata->cpu, tdata->status_reg, &eax, &edx);
> bf6ea084ebb54c Guenter Roeck   2013-11-20  169  		/*
> bf6ea084ebb54c Guenter Roeck   2013-11-20  170  		 * Ignore the valid bit. In all observed cases the register
> bf6ea084ebb54c Guenter Roeck   2013-11-20  171  		 * value is either low or zero if the valid bit is 0.
> bf6ea084ebb54c Guenter Roeck   2013-11-20  172  		 * Return it instead of reporting an error which doesn't
> bf6ea084ebb54c Guenter Roeck   2013-11-20  173  		 * really help at all.
> bf6ea084ebb54c Guenter Roeck   2013-11-20  174  		 */
> bf6ea084ebb54c Guenter Roeck   2013-11-20  175  		tdata->temp = tdata->tjmax - ((eax >> 16) & 0x7f) * 1000;
> 952a11ca32a604 Paul Fertser    2021-09-24  176  		tdata->valid = true;
> 199e0de7f5df31 Durgadoss R     2011-05-20  177  		tdata->last_updated = jiffies;
> bebe467823c0d8 Rudolf Marek    2007-05-08  178  	}
> bebe467823c0d8 Rudolf Marek    2007-05-08  179  
> 199e0de7f5df31 Durgadoss R     2011-05-20  180  	mutex_unlock(&tdata->update_lock);
> bf6ea084ebb54c Guenter Roeck   2013-11-20 @181  	return sprintf(buf, "%d\n", tdata->temp);
> bebe467823c0d8 Rudolf Marek    2007-05-08  182  }
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://01.org/lkp

Thanks,

v3 of the patch should not suffer from this issue.