From: "Kirill A. Shutemov" <[email protected]>
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 <[email protected]>
---
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.
---
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 <linux/cpu.h>
#include <linux/pci.h>
#include <linux/smp.h>
+#include <linux/list.h>
#include <linux/moduleparam.h>
#include <asm/msr.h>
#include <asm/processor.h>
@@ -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);
+ }
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) {
+ 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);
+ }
/*
* If a HT sibling of a core is taken offline, but another HT sibling
--
1.7.9.1
On Tue, 2012-05-08 at 06:49 -0400, Kirill A. Shutemov wrote:
> From: "Kirill A. Shutemov" <[email protected]>
>
> 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 <[email protected]>
> ---
> 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 <linux/cpu.h>
> #include <linux/pci.h>
> #include <linux/smp.h>
> +#include <linux/list.h>
> #include <linux/moduleparam.h>
> #include <asm/msr.h>
> #include <asm/processor.h>
> @@ -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
On Tue, May 08, 2012 at 09:39:40AM -0700, Guenter Roeck wrote:
> On Tue, 2012-05-08 at 06:49 -0400, Kirill A. Shutemov wrote:
> > From: "Kirill A. Shutemov" <[email protected]>
> >
> > 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 <[email protected]>
> > ---
> > 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 ...
Ughh..
> > @@ -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.
I think
if (tdata)
return -ENODEV;
in show methods will fix the issue. Right?
>
> > 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.
Okay, I'll update this.
> > + 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
>
>
--
Kirill A. Shutemov
On Wed, May 09, 2012 at 10:09:06AM +0300, Kirill A. Shutemov wrote:
> On Tue, May 08, 2012 at 09:39:40AM -0700, Guenter Roeck wrote:
> > On Tue, 2012-05-08 at 06:49 -0400, Kirill A. Shutemov wrote:
> > > From: "Kirill A. Shutemov" <[email protected]>
> > >
> > > 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 <[email protected]>
> > > ---
> > > 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 ...
>
> Ughh..
>
> > > @@ -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()
I haven't got how list_for_each_entry_safe() will be really safe without
the lock.
> > 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.
>
> I think
>
> if (tdata)
> return -ENODEV;
>
> in show methods will fix the issue. Right?
It won't. Stupid me.
But the check + kref seems will work...
--
Kirill A. Shutemov
On Wed, May 09, 2012 at 03:23:39AM -0400, Kirill A. Shutemov wrote:
> On Wed, May 09, 2012 at 10:09:06AM +0300, Kirill A. Shutemov wrote:
> > On Tue, May 08, 2012 at 09:39:40AM -0700, Guenter Roeck wrote:
> > > On Tue, 2012-05-08 at 06:49 -0400, Kirill A. Shutemov wrote:
> > > > From: "Kirill A. Shutemov" <[email protected]>
> > > >
> > > > 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 <[email protected]>
> > > > ---
> > > > 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 ...
> >
> > Ughh..
> >
> > > > @@ -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()
>
> I haven't got how list_for_each_entry_safe() will be really safe without
> the lock.
>
We know that it by itself won't be called multiple times. So the only question is
if the functions to add/remove a core can be called while coretemp_remove is called,
or if that is mutually exclusive (not that the current code handles this case).
Fortunately, there is a function to block CPU removal/insertion: get_online_cpus()
and put_online_cpus(). I have no idea if it is necessary to protect coretemp_remove()
with it, but it might be on the safe side anyway.
> > > 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.
> >
> > I think
> >
> > if (tdata)
> > return -ENODEV;
> >
> > in show methods will fix the issue. Right?
>
> It won't. Stupid me.
>
> But the check + kref seems will work...
>
Yes, but would be way too complicated.
Guenter
On Wed, May 09, 2012 at 02:56:17AM -0700, Guenter Roeck wrote:
> On Wed, May 09, 2012 at 03:23:39AM -0400, Kirill A. Shutemov wrote:
> > On Wed, May 09, 2012 at 10:09:06AM +0300, Kirill A. Shutemov wrote:
> > > On Tue, May 08, 2012 at 09:39:40AM -0700, Guenter Roeck wrote:
> > > > On Tue, 2012-05-08 at 06:49 -0400, Kirill A. Shutemov wrote:
> > > > > From: "Kirill A. Shutemov" <[email protected]>
> > > > >
> > > > > 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 <[email protected]>
> > > > > ---
> > > > > 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 ...
> > >
> > > Ughh..
> > >
> > > > > @@ -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()
> >
> > I haven't got how list_for_each_entry_safe() will be really safe without
> > the lock.
> >
> We know that it by itself won't be called multiple times. So the only question is
> if the functions to add/remove a core can be called while coretemp_remove is called,
> or if that is mutually exclusive (not that the current code handles this case).
>
> Fortunately, there is a function to block CPU removal/insertion: get_online_cpus()
> and put_online_cpus(). I have no idea if it is necessary to protect coretemp_remove()
> with it, but it might be on the safe side anyway.
>
> > > > 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.
> > >
> > > I think
> > >
> > > if (tdata)
> > > return -ENODEV;
> > >
> > > in show methods will fix the issue. Right?
> >
> > It won't. Stupid me.
> >
> > But the check + kref seems will work...
> >
> Yes, but would be way too complicated.
More code, yes, but complicated? What you propose looks like a trick. It
has too many assumptions on context.
I personally prefer kref since it's straight forward and more friendly for
future changes.
--
Kirill A. Shutemov
On Wed, May 09, 2012 at 06:16:34AM -0400, Kirill A. Shutemov wrote:
> On Wed, May 09, 2012 at 02:56:17AM -0700, Guenter Roeck wrote:
> > On Wed, May 09, 2012 at 03:23:39AM -0400, Kirill A. Shutemov wrote:
> > > On Wed, May 09, 2012 at 10:09:06AM +0300, Kirill A. Shutemov wrote:
> > > > On Tue, May 08, 2012 at 09:39:40AM -0700, Guenter Roeck wrote:
> > > > > On Tue, 2012-05-08 at 06:49 -0400, Kirill A. Shutemov wrote:
> > > > > > From: "Kirill A. Shutemov" <[email protected]>
> > > > > >
> > > > > > 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 <[email protected]>
> > > > > > ---
> > > > > > 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 ...
> > > >
> > > > Ughh..
> > > >
> > > > > > @@ -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()
> > >
> > > I haven't got how list_for_each_entry_safe() will be really safe without
> > > the lock.
> > >
> > We know that it by itself won't be called multiple times. So the only question is
> > if the functions to add/remove a core can be called while coretemp_remove is called,
> > or if that is mutually exclusive (not that the current code handles this case).
> >
> > Fortunately, there is a function to block CPU removal/insertion: get_online_cpus()
> > and put_online_cpus(). I have no idea if it is necessary to protect coretemp_remove()
> > with it, but it might be on the safe side anyway.
> >
> > > > > 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.
> > > >
> > > > I think
> > > >
> > > > if (tdata)
> > > > return -ENODEV;
> > > >
> > > > in show methods will fix the issue. Right?
> > >
> > > It won't. Stupid me.
> > >
> > > But the check + kref seems will work...
> > >
> > Yes, but would be way too complicated.
>
> More code, yes, but complicated? What you propose looks like a trick. It
> has too many assumptions on context.
>
There is an even better solution: unregistering the hotplug notifier
before removing the driver. And, as you will notice, that is already done.
So list_for_each_entry_safe() is safe after all, since no other remove/add
activity will occur at the same time.
> I personally prefer kref since it's straight forward and more friendly for
> future changes.
>
Guess we have to agree to disagree on that one.
Thanks,
Guenter