Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757130Ab2EHQmK (ORCPT ); Tue, 8 May 2012 12:42:10 -0400 Received: from imr4.ericy.com ([198.24.6.9]:52760 "EHLO imr4.ericy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756726Ab2EHQmI (ORCPT ); Tue, 8 May 2012 12:42:08 -0400 Message-ID: <1336495180.22553.68.camel@groeck-laptop> Subject: Re: [PATCH, v4] hwmon: coretemp: use list instead of fixed size array for temp data From: Guenter Roeck Reply-To: guenter.roeck@ericsson.com To: "Kirill A. Shutemov" CC: Fenghua Yu , Durgadoss R , Andi Kleen , Jean Delvare , "lm-sensors@lm-sensors.org" , "linux-kernel@vger.kernel.org" Date: Tue, 8 May 2012 09:39:40 -0700 In-Reply-To: <1336474175-5714-1-git-send-email-kirill.shutemov@linux.intel.com> References: <1336474175-5714-1-git-send-email-kirill.shutemov@linux.intel.com> Organization: Ericsson Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.2- Content-Transfer-Encoding: 7bit MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11498 Lines: 340 On Tue, 2012-05-08 at 06:49 -0400, Kirill A. Shutemov wrote: > From: "Kirill A. Shutemov" > > Let's rework code to allow arbitrary number of cores on a CPU, not > limited by hardcoded array size. > > Signed-off-by: Kirill A. Shutemov > --- > v4: > - address issues pointed by Guenter Roeck; > v3: > - drop redundant refcounting and checks; > v2: > - fix NULL pointer dereference. Thanks to R, Durgadoss; > - use mutex instead of spinlock for list locking. > --- Hi Kirill, unfortunately now we have another race condition :(. See below ... > drivers/hwmon/coretemp.c | 119 ++++++++++++++++++++++++++++++---------------- > 1 files changed, 78 insertions(+), 41 deletions(-) > > diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c > index b9d5123..602bdc8 100644 > --- a/drivers/hwmon/coretemp.c > +++ b/drivers/hwmon/coretemp.c > @@ -36,6 +36,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -52,11 +53,9 @@ module_param_named(tjmax, force_tjmax, int, 0444); > MODULE_PARM_DESC(tjmax, "TjMax value in degrees Celsius"); > > #define BASE_SYSFS_ATTR_NO 2 /* Sysfs Base attr no for coretemp */ > -#define NUM_REAL_CORES 32 /* Number of Real cores per cpu */ > #define CORETEMP_NAME_LENGTH 17 /* String Length of attrs */ > #define MAX_CORE_ATTRS 4 /* Maximum no of basic attrs */ > #define TOTAL_ATTRS (MAX_CORE_ATTRS + 1) > -#define MAX_CORE_DATA (NUM_REAL_CORES + BASE_SYSFS_ATTR_NO) > > #define TO_PHYS_ID(cpu) (cpu_data(cpu).phys_proc_id) > #define TO_CORE_ID(cpu) (cpu_data(cpu).cpu_core_id) > @@ -82,6 +81,8 @@ MODULE_PARM_DESC(tjmax, "TjMax value in degrees Celsius"); > * @valid: If this is 1, the current temperature is valid. > */ > struct temp_data { > + struct list_head list; > + int id; > int temp; > int ttarget; > int tjmax; > @@ -101,7 +102,8 @@ struct temp_data { > struct platform_data { > struct device *hwmon_dev; > u16 phys_proc_id; > - struct temp_data *core_data[MAX_CORE_DATA]; > + struct list_head temp_data_list; > + struct mutex temp_data_lock; > struct device_attribute name_attr; > }; > > @@ -114,6 +116,20 @@ struct pdev_entry { > static LIST_HEAD(pdev_list); > static DEFINE_MUTEX(pdev_list_mutex); > > +static struct temp_data *get_temp_data(struct platform_data *pdata, int id) > +{ > + struct temp_data *tdata; > + > + mutex_lock(&pdata->temp_data_lock); > + list_for_each_entry(tdata, &pdata->temp_data_list, list) > + if (tdata->id == id) > + goto out; > + tdata = NULL; > +out: > + mutex_unlock(&pdata->temp_data_lock); > + return tdata; > +} > + > static ssize_t show_name(struct device *dev, > struct device_attribute *devattr, char *buf) > { > @@ -125,7 +141,7 @@ static ssize_t show_label(struct device *dev, > { > struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); > struct platform_data *pdata = dev_get_drvdata(dev); > - struct temp_data *tdata = pdata->core_data[attr->index]; > + struct temp_data *tdata = get_temp_data(pdata, attr->index); > > if (tdata->is_pkg_data) > return sprintf(buf, "Physical id %u\n", pdata->phys_proc_id); > @@ -139,7 +155,7 @@ static ssize_t show_crit_alarm(struct device *dev, > u32 eax, edx; > struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); > struct platform_data *pdata = dev_get_drvdata(dev); > - struct temp_data *tdata = pdata->core_data[attr->index]; > + struct temp_data *tdata = get_temp_data(pdata, attr->index); > > rdmsr_on_cpu(tdata->cpu, tdata->status_reg, &eax, &edx); > > @@ -151,8 +167,9 @@ static ssize_t show_tjmax(struct device *dev, > { > struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); > struct platform_data *pdata = dev_get_drvdata(dev); > + struct temp_data *tdata = get_temp_data(pdata, attr->index); > > - return sprintf(buf, "%d\n", pdata->core_data[attr->index]->tjmax); > + return sprintf(buf, "%d\n", tdata->tjmax); > } > > static ssize_t show_ttarget(struct device *dev, > @@ -160,8 +177,9 @@ static ssize_t show_ttarget(struct device *dev, > { > struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); > struct platform_data *pdata = dev_get_drvdata(dev); > + struct temp_data *tdata = get_temp_data(pdata, attr->index); > > - return sprintf(buf, "%d\n", pdata->core_data[attr->index]->ttarget); > + return sprintf(buf, "%d\n", tdata->ttarget); > } > > static ssize_t show_temp(struct device *dev, > @@ -170,7 +188,7 @@ static ssize_t show_temp(struct device *dev, > u32 eax, edx; > struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); > struct platform_data *pdata = dev_get_drvdata(dev); > - struct temp_data *tdata = pdata->core_data[attr->index]; > + struct temp_data *tdata = get_temp_data(pdata, attr->index); > > mutex_lock(&tdata->update_lock); > > @@ -423,7 +441,7 @@ static struct temp_data __cpuinit *init_temp_data(unsigned int cpu, > return tdata; > } > > -static int __cpuinit create_core_data(struct platform_device *pdev, > +static int __cpuinit create_temp_data(struct platform_device *pdev, > unsigned int cpu, int pkg_flag) > { > struct temp_data *tdata; > @@ -440,9 +458,6 @@ static int __cpuinit create_core_data(struct platform_device *pdev, > */ > attr_no = pkg_flag ? 1 : TO_ATTR_NO(cpu); > > - if (attr_no > MAX_CORE_DATA - 1) > - return -ERANGE; > - > /* > * Provide a single set of attributes for all HT siblings of a core > * to avoid duplicate sensors (the processor ID and core ID of all > @@ -450,7 +465,8 @@ static int __cpuinit create_core_data(struct platform_device *pdev, > * Skip if a HT sibling of this core is already registered. > * This is not an error. > */ > - if (pdata->core_data[attr_no] != NULL) > + tdata = get_temp_data(pdata, attr_no); > + if (tdata) > return 0; > > tdata = init_temp_data(cpu, pkg_flag); > @@ -480,16 +496,23 @@ static int __cpuinit create_core_data(struct platform_device *pdev, > } > } > > - pdata->core_data[attr_no] = tdata; > + tdata->id = attr_no; > + > + mutex_lock(&pdata->temp_data_lock); > + list_add(&tdata->list, &pdata->temp_data_list); > + mutex_unlock(&pdata->temp_data_lock); > > /* Create sysfs interfaces */ > err = create_core_attrs(tdata, &pdev->dev, attr_no); > if (err) > - goto exit_free; > + goto exit_list_del; > > return 0; > +exit_list_del: > + mutex_lock(&pdata->temp_data_lock); > + list_del(&tdata->list); > + mutex_unlock(&pdata->temp_data_lock); > exit_free: > - pdata->core_data[attr_no] = NULL; > kfree(tdata); > return err; > } > @@ -502,23 +525,20 @@ static void __cpuinit coretemp_add_core(unsigned int cpu, int pkg_flag) > if (!pdev) > return; > > - err = create_core_data(pdev, cpu, pkg_flag); > + err = create_temp_data(pdev, cpu, pkg_flag); > if (err) > dev_err(&pdev->dev, "Adding Core %u failed\n", cpu); > } > > -static void coretemp_remove_core(struct platform_data *pdata, > - struct device *dev, int indx) > +static void coretemp_remove_core(struct temp_data *tdata, struct device *dev) > { > int i; > - struct temp_data *tdata = pdata->core_data[indx]; > > /* Remove the sysfs attributes */ > for (i = 0; i < tdata->attr_size; i++) > device_remove_file(dev, &tdata->sd_attrs[i].dev_attr); > > - kfree(pdata->core_data[indx]); > - pdata->core_data[indx] = NULL; > + kfree(tdata); > } > > static int __devinit coretemp_probe(struct platform_device *pdev) > @@ -536,6 +556,8 @@ static int __devinit coretemp_probe(struct platform_device *pdev) > goto exit_free; > > pdata->phys_proc_id = pdev->id; > + INIT_LIST_HEAD(&pdata->temp_data_list); > + mutex_init(&pdata->temp_data_lock); > platform_set_drvdata(pdev, pdata); > > pdata->hwmon_dev = hwmon_device_register(&pdev->dev); > @@ -557,11 +579,22 @@ exit_free: > static int __devexit coretemp_remove(struct platform_device *pdev) > { > struct platform_data *pdata = platform_get_drvdata(pdev); > - int i; > + struct temp_data *tdata; > > - for (i = MAX_CORE_DATA - 1; i >= 0; --i) > - if (pdata->core_data[i]) > - coretemp_remove_core(pdata, &pdev->dev, i); > + for (;;) { > + mutex_lock(&pdata->temp_data_lock); > + if (!list_empty(&pdata->temp_data_list)) { > + tdata = list_first_entry(&pdata->temp_data_list, > + struct temp_data, list); > + list_del(&tdata->list); > + } else > + tdata = NULL; > + mutex_unlock(&pdata->temp_data_lock); > + > + if (!tdata) > + break; > + coretemp_remove_core(tdata, &pdev->dev); > + } > Unfortunately, that results in a race condition, since the tdata list entry is gone before the attribute file is deleted. I think you can still use list_for_each_entry_safe, only outside the mutex, and remove the list entry at the end of coretemp_remove_core() after deleting the attribute file. Just keep the code as it was, and remove the list entry (mutex-protected) where core_data[] was set to NULL. > device_remove_file(&pdev->dev, &pdata->name_attr); > hwmon_device_unregister(pdata->hwmon_dev); > @@ -641,16 +674,18 @@ static void __cpuinit coretemp_device_remove(unsigned int cpu) > > static bool __cpuinit is_any_core_online(struct platform_data *pdata) > { > - int i; > + struct temp_data *tdata; > + bool ret = false; > > - /* Find online cores, except pkgtemp data */ > - for (i = MAX_CORE_DATA - 1; i >= 0; --i) { > - if (pdata->core_data[i] && > - !pdata->core_data[i]->is_pkg_data) { > - return true; > + mutex_lock(&pdata->temp_data_lock); > + list_for_each_entry(tdata, &pdata->temp_data_list, list) { > + if (!tdata->is_pkg_data) { Actually, we don't need is_pkg_data anymore at all. Just test for "tdata->id == 1" instead. That will simplify the code a bit. > + ret = true; > + break; > } > } > - return false; > + mutex_unlock(&pdata->temp_data_lock); > + return ret; > } > > static void __cpuinit get_core_online(unsigned int cpu) > @@ -697,9 +732,10 @@ static void __cpuinit get_core_online(unsigned int cpu) > > static void __cpuinit put_core_offline(unsigned int cpu) > { > - int i, indx; > + int i, attr_no; > struct platform_data *pdata; > struct platform_device *pdev = coretemp_get_pdev(cpu); > + struct temp_data *tdata; > > /* If the physical CPU device does not exist, just return */ > if (!pdev) > @@ -707,14 +743,15 @@ static void __cpuinit put_core_offline(unsigned int cpu) > > pdata = platform_get_drvdata(pdev); > > - indx = TO_ATTR_NO(cpu); > + attr_no = TO_ATTR_NO(cpu); > > - /* The core id is too big, just return */ > - if (indx > MAX_CORE_DATA - 1) > - return; > - > - if (pdata->core_data[indx] && pdata->core_data[indx]->cpu == cpu) > - coretemp_remove_core(pdata, &pdev->dev, indx); > + tdata = get_temp_data(pdata, attr_no); > + if (tdata && tdata->cpu == cpu) { > + mutex_lock(&pdata->temp_data_lock); > + list_del(&tdata->list); > + mutex_unlock(&pdata->temp_data_lock); > + coretemp_remove_core(tdata, &pdev->dev); Same race condition as above here. > + } > > /* > * If a HT sibling of a core is taken offline, but another HT sibling -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/