[PATCH v2 0/3] thermal: Cleanups

[PATCH v2 0/3] thermal: Cleanups

[Jean Delvare]

[PATCH 1/3] thermal: Hide CONFIG_THERMAL_HWMON
[PATCH 2/3] thermal: Split hwmon lookup to a separate function
[PATCH 3/3] thermal: Make THERMAL_HWMON implementation fully internal

-- 
Jean Delvare

[PATCH v2 1/3] thermal: Hide CONFIG_THERMAL_HWMON

[Jean Delvare]

It's about time to revert 16d752397301b95abaa95cbaf9e785d221872311.
Anybody running a kernel >= 2.6.40 would also be running a recent
enough version of lm-sensors.

Actually having CONFIG_THERMAL_HWMON is pretty convenient so instead
of dopping it, we keep it but hide it.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Rene Herman <rene.herman@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Guenter Roeck <guenter.roeck@ericsson.com>
---
 Documentation/feature-removal-schedule.txt |    9 ---------
 drivers/thermal/Kconfig                    |    8 ++------
 2 files changed, 2 insertions(+), 15 deletions(-)

--- linux-2.6.39-rc4.orig/Documentation/feature-removal-schedule.txt	2011-04-25 16:16:10.000000000 +0200
+++ linux-2.6.39-rc4/Documentation/feature-removal-schedule.txt	2011-04-26 09:29:09.000000000 +0200
@@ -295,15 +295,6 @@ Who:	Ravikiran Thirumalai <kiran@scalex8
 
 ---------------------------
 
-What:	CONFIG_THERMAL_HWMON
-When:	January 2009
-Why:	This option was introduced just to allow older lm-sensors userspace
-	to keep working over the upgrade to 2.6.26. At the scheduled time of
-	removal fixed lm-sensors (2.x or 3.x) should be readily available.
-Who:	Rene Herman <rene.herman@gmail.com>
-
----------------------------
-
 What:	Code that is now under CONFIG_WIRELESS_EXT_SYSFS
 	(in net/core/net-sysfs.c)
 When:	After the only user (hal) has seen a release with the patches
--- linux-2.6.39-rc4.orig/drivers/thermal/Kconfig	2011-04-25 16:16:10.000000000 +0200
+++ linux-2.6.39-rc4/drivers/thermal/Kconfig	2011-04-26 09:32:30.000000000 +0200
@@ -14,11 +14,7 @@ menuconfig THERMAL
 	  If you want this support, you should say Y or M here.
 
 config THERMAL_HWMON
-	bool "Hardware monitoring support"
+	bool
 	depends on THERMAL
 	depends on HWMON=y || HWMON=THERMAL
-	help
-	  The generic thermal sysfs driver's hardware monitoring support
-	  requires a 2.10.7/3.0.2 or later lm-sensors userspace.
-
-	  Say Y if your user-space is new enough.
+	default y

-- 
Jean Delvare

Re: [PATCH v2 1/3] thermal: Hide CONFIG_THERMAL_HWMON

[Guenter Roeck]

On Tue, Apr 26, 2011 at 11:02:08AM -0400, Jean Delvare wrote:
> It's about time to revert 16d752397301b95abaa95cbaf9e785d221872311.
> Anybody running a kernel >= 2.6.40 would also be running a recent
> enough version of lm-sensors.
> 
> Actually having CONFIG_THERMAL_HWMON is pretty convenient so instead
> of dopping it, we keep it but hide it.
> 
> Signed-off-by: Jean Delvare <khali@linux-fr.org>
> Cc: Rene Herman <rene.herman@gmail.com>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Guenter Roeck <guenter.roeck@ericsson.com>

Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>

[PATCH v2 2/3] thermal: Split hwmon lookup to a separate function

[Jean Delvare]

We'll soon need to reuse it.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Rene Herman <rene.herman@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Guenter Roeck <guenter.roeck@ericsson.com>
---
 drivers/thermal/thermal_sys.c |   25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

--- linux-2.6.39-rc4.orig/drivers/thermal/thermal_sys.c	2011-04-25 14:40:17.000000000 +0200
+++ linux-2.6.39-rc4/drivers/thermal/thermal_sys.c	2011-04-25 14:44:52.000000000 +0200
@@ -469,22 +469,35 @@ temp_crit_show(struct device *dev, struc
 }
 
 
-static int
-thermal_add_hwmon_sysfs(struct thermal_zone_device *tz)
+static struct thermal_hwmon_device *
+thermal_hwmon_lookup_by_type(const struct thermal_zone_device *tz)
 {
 	struct thermal_hwmon_device *hwmon;
-	int new_hwmon_device = 1;
-	int result;
 
 	mutex_lock(&thermal_list_lock);
 	list_for_each_entry(hwmon, &thermal_hwmon_list, node)
 		if (!strcmp(hwmon->type, tz->type)) {
-			new_hwmon_device = 0;
 			mutex_unlock(&thermal_list_lock);
-			goto register_sys_interface;
+			return hwmon;
 		}
 	mutex_unlock(&thermal_list_lock);
 
+	return NULL;
+}
+
+static int
+thermal_add_hwmon_sysfs(struct thermal_zone_device *tz)
+{
+	struct thermal_hwmon_device *hwmon;
+	int new_hwmon_device = 1;
+	int result;
+
+	hwmon = thermal_hwmon_lookup_by_type(tz);
+	if (hwmon) {
+		new_hwmon_device = 0;
+		goto register_sys_interface;
+	}
+
 	hwmon = kzalloc(sizeof(struct thermal_hwmon_device), GFP_KERNEL);
 	if (!hwmon)
 		return -ENOMEM;

-- 
Jean Delvare

Re: [PATCH v2 2/3] thermal: Split hwmon lookup to a separate function

[Guenter Roeck]

On Tue, Apr 26, 2011 at 11:02:53AM -0400, Jean Delvare wrote:
> We'll soon need to reuse it.
> 
> Signed-off-by: Jean Delvare <khali@linux-fr.org>
> Cc: Rene Herman <rene.herman@gmail.com>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Guenter Roeck <guenter.roeck@ericsson.com>

Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>

[PATCH v2 3/3] thermal: Make THERMAL_HWMON implementation fully internal

[Jean Delvare]

THERMAL_HWMON is implemented inside the thermal_sys driver and has no
effect on drivers implementing thermal zones, so they shouldn't see
anything related to it in <linux/thermal.h>. Making the THERMAL_HWMON
implementation fully internal has two advantages beyond the cleaner
design:
* This avoids rebuilding all thermal drivers if the THERMAL_HWMON
  implementation changes, or if CONFIG_THERMAL_HWMON gets enabled or
  disabled.
* This avoids breaking the thermal kABI in these cases too, which
  should make distributions happy.

The only drawback I can see is slightly higher memory fragmentation,
as the number of kzalloc() calls will increase by one per thermal zone.
But I doubt it will be a problem in practice, as I've never seen a
system with more than two thermal zones.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Rene Herman <rene.herman@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Guenter Roeck <guenter.roeck@ericsson.com>
---
* If memory fragmentation is really a concern to anyone, it would be
  possible to save one kalloc for the first temperature input of each
  zone type, as the price of slightly more complex code.

* Removal code path is untested, as I have never been able to unload
the thermal_sys module on any of my systems. Something is pinning it
and I have no idea what it is.

 drivers/thermal/thermal_sys.c |  116 ++++++++++++++++++++++++++++++++---------
 include/linux/thermal.h       |   22 -------
 2 files changed, 91 insertions(+), 47 deletions(-)

--- linux-2.6.39-rc4.orig/drivers/thermal/thermal_sys.c	2011-04-26 10:30:29.000000000 +0200
+++ linux-2.6.39-rc4/drivers/thermal/thermal_sys.c	2011-04-26 11:05:38.000000000 +0200
@@ -420,6 +420,29 @@ thermal_cooling_device_trip_point_show(s
 
 /* hwmon sys I/F */
 #include <linux/hwmon.h>
+
+/* thermal zone devices with the same type share one hwmon device */
+struct thermal_hwmon_device {
+	char type[THERMAL_NAME_LENGTH];
+	struct device *device;
+	int count;
+	struct list_head tz_list;
+	struct list_head node;
+};
+
+struct thermal_hwmon_attr {
+	struct device_attribute attr;
+	char name[16];
+};
+
+/* one temperature input for each thermal zone */
+struct thermal_hwmon_temp {
+	struct list_head hwmon_node;
+	struct thermal_zone_device *tz;
+	struct thermal_hwmon_attr temp_input;	/* hwmon sys attr */
+	struct thermal_hwmon_attr temp_crit;	/* hwmon sys attr */
+};
+
 static LIST_HEAD(thermal_hwmon_list);
 
 static ssize_t
@@ -437,9 +460,10 @@ temp_input_show(struct device *dev, stru
 	int ret;
 	struct thermal_hwmon_attr *hwmon_attr
 			= container_of(attr, struct thermal_hwmon_attr, attr);
-	struct thermal_zone_device *tz
-			= container_of(hwmon_attr, struct thermal_zone_device,
+	struct thermal_hwmon_temp *temp
+			= container_of(hwmon_attr, struct thermal_hwmon_temp,
 				       temp_input);
+	struct thermal_zone_device *tz = temp->tz;
 
 	ret = tz->ops->get_temp(tz, &temperature);
 
@@ -455,9 +479,10 @@ temp_crit_show(struct device *dev, struc
 {
 	struct thermal_hwmon_attr *hwmon_attr
 			= container_of(attr, struct thermal_hwmon_attr, attr);
-	struct thermal_zone_device *tz
-			= container_of(hwmon_attr, struct thermal_zone_device,
+	struct thermal_hwmon_temp *temp
+			= container_of(hwmon_attr, struct thermal_hwmon_temp,
 				       temp_crit);
+	struct thermal_zone_device *tz = temp->tz;
 	long temperature;
 	int ret;
 
@@ -485,10 +510,29 @@ thermal_hwmon_lookup_by_type(const struc
 	return NULL;
 }
 
+/* Find the temperature input matching a given thermal zone */
+static struct thermal_hwmon_temp *
+thermal_hwmon_lookup_temp(const struct thermal_hwmon_device *hwmon,
+			  const struct thermal_zone_device *tz)
+{
+	struct thermal_hwmon_temp *temp;
+
+	mutex_lock(&thermal_list_lock);
+	list_for_each_entry(temp, &hwmon->tz_list, hwmon_node)
+		if (temp->tz == tz) {
+			mutex_unlock(&thermal_list_lock);
+			return temp;
+		}
+	mutex_unlock(&thermal_list_lock);
+
+	return NULL;
+}
+
 static int
 thermal_add_hwmon_sysfs(struct thermal_zone_device *tz)
 {
 	struct thermal_hwmon_device *hwmon;
+	struct thermal_hwmon_temp *temp = NULL;
 	int new_hwmon_device = 1;
 	int result;
 
@@ -515,30 +559,36 @@ thermal_add_hwmon_sysfs(struct thermal_z
 		goto unregister_hwmon_device;
 
  register_sys_interface:
-	tz->hwmon = hwmon;
+	temp = kzalloc(sizeof(struct thermal_hwmon_temp), GFP_KERNEL);
+	if (!temp) {
+		result = -ENOMEM;
+		goto unregister_hwmon_device;
+	}
+
+	temp->tz = tz;
 	hwmon->count++;
 
-	snprintf(tz->temp_input.name, THERMAL_NAME_LENGTH,
+	snprintf(temp->temp_input.name, THERMAL_NAME_LENGTH,
 		 "temp%d_input", hwmon->count);
-	tz->temp_input.attr.attr.name = tz->temp_input.name;
-	tz->temp_input.attr.attr.mode = 0444;
-	tz->temp_input.attr.show = temp_input_show;
-	sysfs_attr_init(&tz->temp_input.attr.attr);
-	result = device_create_file(hwmon->device, &tz->temp_input.attr);
+	temp->temp_input.attr.attr.name = temp->temp_input.name;
+	temp->temp_input.attr.attr.mode = 0444;
+	temp->temp_input.attr.show = temp_input_show;
+	sysfs_attr_init(&temp->temp_input.attr.attr);
+	result = device_create_file(hwmon->device, &temp->temp_input.attr);
 	if (result)
 		goto unregister_hwmon_device;
 
 	if (tz->ops->get_crit_temp) {
 		unsigned long temperature;
 		if (!tz->ops->get_crit_temp(tz, &temperature)) {
-			snprintf(tz->temp_crit.name, THERMAL_NAME_LENGTH,
+			snprintf(temp->temp_crit.name, THERMAL_NAME_LENGTH,
 				"temp%d_crit", hwmon->count);
-			tz->temp_crit.attr.attr.name = tz->temp_crit.name;
-			tz->temp_crit.attr.attr.mode = 0444;
-			tz->temp_crit.attr.show = temp_crit_show;
-			sysfs_attr_init(&tz->temp_crit.attr.attr);
+			temp->temp_crit.attr.attr.name = temp->temp_crit.name;
+			temp->temp_crit.attr.attr.mode = 0444;
+			temp->temp_crit.attr.show = temp_crit_show;
+			sysfs_attr_init(&temp->temp_crit.attr.attr);
 			result = device_create_file(hwmon->device,
-						    &tz->temp_crit.attr);
+						    &temp->temp_crit.attr);
 			if (result)
 				goto unregister_hwmon_device;
 		}
@@ -547,14 +597,15 @@ thermal_add_hwmon_sysfs(struct thermal_z
 	mutex_lock(&thermal_list_lock);
 	if (new_hwmon_device)
 		list_add_tail(&hwmon->node, &thermal_hwmon_list);
-	list_add_tail(&tz->hwmon_node, &hwmon->tz_list);
+	list_add_tail(&temp->hwmon_node, &hwmon->tz_list);
 	mutex_unlock(&thermal_list_lock);
 
 	return 0;
 
  unregister_hwmon_device:
-	device_remove_file(hwmon->device, &tz->temp_crit.attr);
-	device_remove_file(hwmon->device, &tz->temp_input.attr);
+	device_remove_file(hwmon->device, &temp->temp_crit.attr);
+	device_remove_file(hwmon->device, &temp->temp_input.attr);
+	kfree(temp);
 	if (new_hwmon_device) {
 		device_remove_file(hwmon->device, &dev_attr_name);
 		hwmon_device_unregister(hwmon->device);
@@ -569,15 +620,30 @@ thermal_add_hwmon_sysfs(struct thermal_z
 static void
 thermal_remove_hwmon_sysfs(struct thermal_zone_device *tz)
 {
-	struct thermal_hwmon_device *hwmon = tz->hwmon;
+	struct thermal_hwmon_device *hwmon;
+	struct thermal_hwmon_temp *temp;
 
-	tz->hwmon = NULL;
-	device_remove_file(hwmon->device, &tz->temp_input.attr);
+	hwmon = thermal_hwmon_lookup_by_type(tz);
+	if (unlikely(!hwmon)) {
+		/* Should never happen... */
+		dev_dbg(&tz->device, "hwmon device lookup failed!\n");
+		return;
+	}
+
+	temp = thermal_hwmon_lookup_temp(hwmon, tz);
+	if (unlikely(!temp)) {
+		/* Should never happen... */
+		dev_dbg(&tz->device, "temperature input lookup failed!\n");
+		return;
+	}
+
+	device_remove_file(hwmon->device, &temp->temp_input.attr);
 	if (tz->ops->get_crit_temp)
-		device_remove_file(hwmon->device, &tz->temp_crit.attr);
+		device_remove_file(hwmon->device, &temp->temp_crit.attr);
 
 	mutex_lock(&thermal_list_lock);
-	list_del(&tz->hwmon_node);
+	list_del(&temp->hwmon_node);
+	kfree(temp);
 	if (!list_empty(&hwmon->tz_list)) {
 		mutex_unlock(&thermal_list_lock);
 		return;
--- linux-2.6.39-rc4.orig/include/linux/thermal.h	2011-04-25 16:16:10.000000000 +0200
+++ linux-2.6.39-rc4/include/linux/thermal.h	2011-04-26 10:40:46.000000000 +0200
@@ -85,22 +85,6 @@ struct thermal_cooling_device {
 				((long)t-2732+5)/10 : ((long)t-2732-5)/10)
 #define CELSIUS_TO_KELVIN(t)	((t)*10+2732)
 
-#if defined(CONFIG_THERMAL_HWMON)
-/* thermal zone devices with the same type share one hwmon device */
-struct thermal_hwmon_device {
-	char type[THERMAL_NAME_LENGTH];
-	struct device *device;
-	int count;
-	struct list_head tz_list;
-	struct list_head node;
-};
-
-struct thermal_hwmon_attr {
-	struct device_attribute attr;
-	char name[16];
-};
-#endif
-
 struct thermal_zone_device {
 	int id;
 	char type[THERMAL_NAME_LENGTH];
@@ -120,12 +104,6 @@ struct thermal_zone_device {
 	struct mutex lock;	/* protect cooling devices list */
 	struct list_head node;
 	struct delayed_work poll_queue;
-#if defined(CONFIG_THERMAL_HWMON)
-	struct list_head hwmon_node;
-	struct thermal_hwmon_device *hwmon;
-	struct thermal_hwmon_attr temp_input;	/* hwmon sys attr */
-	struct thermal_hwmon_attr temp_crit;	/* hwmon sys attr */
-#endif
 };
 /* Adding event notification support elements */
 #define THERMAL_GENL_FAMILY_NAME                "thermal_event"

-- 
Jean Delvare

Re: [PATCH v2 3/3] thermal: Make THERMAL_HWMON implementation fully internal

[Guenter Roeck]

On Tue, Apr 26, 2011 at 11:04:07AM -0400, Jean Delvare wrote:
> THERMAL_HWMON is implemented inside the thermal_sys driver and has no
> effect on drivers implementing thermal zones, so they shouldn't see
> anything related to it in <linux/thermal.h>. Making the THERMAL_HWMON
> implementation fully internal has two advantages beyond the cleaner
> design:
> * This avoids rebuilding all thermal drivers if the THERMAL_HWMON
>   implementation changes, or if CONFIG_THERMAL_HWMON gets enabled or
>   disabled.
> * This avoids breaking the thermal kABI in these cases too, which
>   should make distributions happy.
> 
> The only drawback I can see is slightly higher memory fragmentation,
> as the number of kzalloc() calls will increase by one per thermal zone.
> But I doubt it will be a problem in practice, as I've never seen a
> system with more than two thermal zones.
> 
> Signed-off-by: Jean Delvare <khali@linux-fr.org>
> Cc: Rene Herman <rene.herman@gmail.com>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Guenter Roeck <guenter.roeck@ericsson.com>
> ---
> * If memory fragmentation is really a concern to anyone, it would be
>   possible to save one kalloc for the first temperature input of each
>   zone type, as the price of slightly more complex code.
> 
> * Removal code path is untested, as I have never been able to unload
> the thermal_sys module on any of my systems. Something is pinning it
> and I have no idea what it is.
> 
Doesn't lsmod show the culprit ?

Otherwise

Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>

Re: [PATCH v2 3/3] thermal: Make THERMAL_HWMON implementation fully internal

[Jean Delvare]

On Tue, 26 Apr 2011 08:52:12 -0700, Guenter Roeck wrote:
> On Tue, Apr 26, 2011 at 11:04:07AM -0400, Jean Delvare wrote:
> > THERMAL_HWMON is implemented inside the thermal_sys driver and has no
> > effect on drivers implementing thermal zones, so they shouldn't see
> > anything related to it in <linux/thermal.h>. Making the THERMAL_HWMON
> > implementation fully internal has two advantages beyond the cleaner
> > design:
> > * This avoids rebuilding all thermal drivers if the THERMAL_HWMON
> >   implementation changes, or if CONFIG_THERMAL_HWMON gets enabled or
> >   disabled.
> > * This avoids breaking the thermal kABI in these cases too, which
> >   should make distributions happy.
> > 
> > The only drawback I can see is slightly higher memory fragmentation,
> > as the number of kzalloc() calls will increase by one per thermal zone.
> > But I doubt it will be a problem in practice, as I've never seen a
> > system with more than two thermal zones.
> > 
> > Signed-off-by: Jean Delvare <khali@linux-fr.org>
> > Cc: Rene Herman <rene.herman@gmail.com>
> > Cc: Len Brown <len.brown@intel.com>
> > Cc: Guenter Roeck <guenter.roeck@ericsson.com>
> > ---
> > * If memory fragmentation is really a concern to anyone, it would be
> >   possible to save one kalloc for the first temperature input of each
> >   zone type, as the price of slightly more complex code.
> > 
> > * Removal code path is untested, as I have never been able to unload
> > the thermal_sys module on any of my systems. Something is pinning it
> > and I have no idea what it is.
> > 
> Doesn't lsmod show the culprit ?

No, it's not a module dependency. The reference counter is set to 1,
so somewhere in the kernel something is taking a reference to the
module and won't release it. I wish this was better instrumented so
that it would be possible to know who is doing that.

> Otherwise
> 
> Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>

Thanks for the reviews.

-- 
Jean Delvare

Re: [PATCH v2 3/3] thermal: Make THERMAL_HWMON implementation fully internal

[Guenter Roeck]

On Tue, 2011-04-26 at 12:29 -0400, Jean Delvare wrote:
> On Tue, 26 Apr 2011 08:52:12 -0700, Guenter Roeck wrote:
> > On Tue, Apr 26, 2011 at 11:04:07AM -0400, Jean Delvare wrote:
> > > THERMAL_HWMON is implemented inside the thermal_sys driver and has no
> > > effect on drivers implementing thermal zones, so they shouldn't see
> > > anything related to it in <linux/thermal.h>. Making the THERMAL_HWMON
> > > implementation fully internal has two advantages beyond the cleaner
> > > design:
> > > * This avoids rebuilding all thermal drivers if the THERMAL_HWMON
> > >   implementation changes, or if CONFIG_THERMAL_HWMON gets enabled or
> > >   disabled.
> > > * This avoids breaking the thermal kABI in these cases too, which
> > >   should make distributions happy.
> > > 
> > > The only drawback I can see is slightly higher memory fragmentation,
> > > as the number of kzalloc() calls will increase by one per thermal zone.
> > > But I doubt it will be a problem in practice, as I've never seen a
> > > system with more than two thermal zones.
> > > 
> > > Signed-off-by: Jean Delvare <khali@linux-fr.org>
> > > Cc: Rene Herman <rene.herman@gmail.com>
> > > Cc: Len Brown <len.brown@intel.com>
> > > Cc: Guenter Roeck <guenter.roeck@ericsson.com>
> > > ---
> > > * If memory fragmentation is really a concern to anyone, it would be
> > >   possible to save one kalloc for the first temperature input of each
> > >   zone type, as the price of slightly more complex code.
> > > 
> > > * Removal code path is untested, as I have never been able to unload
> > > the thermal_sys module on any of my systems. Something is pinning it
> > > and I have no idea what it is.
> > > 
> > Doesn't lsmod show the culprit ?
> 
> No, it's not a module dependency. The reference counter is set to 1,
> so somewhere in the kernel something is taking a reference to the
> module and won't release it. I wish this was better instrumented so
> that it would be possible to know who is doing that.

The most likely culprit seems to be acpi.

Guenter

Re: [PATCH v2 3/3] thermal: Make THERMAL_HWMON implementation fully internal

[Jean Delvare]

Hi Guenter,

On Tue, 26 Apr 2011 10:43:32 -0700, Guenter Roeck wrote:
> On Tue, 2011-04-26 at 12:29 -0400, Jean Delvare wrote:
> > On Tue, 26 Apr 2011 08:52:12 -0700, Guenter Roeck wrote:
> > > On Tue, Apr 26, 2011 at 11:04:07AM -0400, Jean Delvare wrote:
> > > > * Removal code path is untested, as I have never been able to unload
> > > > the thermal_sys module on any of my systems. Something is pinning it
> > > > and I have no idea what it is.
> > > > 
> > > Doesn't lsmod show the culprit ?
> > 
> > No, it's not a module dependency. The reference counter is set to 1,

Sorry I realize I have been inaccurate. thermal_sys indeed depends on
the processor module, and that's what prevents me from unloading it.
It's the processor module which has a reference count of 1, and no
dependency, so I have no idea how I could unload it.

> > so somewhere in the kernel something is taking a reference to the
> > module and won't release it. I wish this was better instrumented so
> > that it would be possible to know who is doing that.
> 
> The most likely culprit seems to be acpi.

I'm not sure. I don't see any relevant call to try_module_get under
drivers/acpi, and I'm not aware of any other way to increase the
reference count.

-- 
Jean Delvare

Re: [PATCH v2 3/3] thermal: Make THERMAL_HWMON implementation fully internal

[Guenter Roeck]

On Tue, 2011-04-26 at 15:39 -0400, Jean Delvare wrote:
> Hi Guenter,
> 
> On Tue, 26 Apr 2011 10:43:32 -0700, Guenter Roeck wrote:
> > On Tue, 2011-04-26 at 12:29 -0400, Jean Delvare wrote:
> > > On Tue, 26 Apr 2011 08:52:12 -0700, Guenter Roeck wrote:
> > > > On Tue, Apr 26, 2011 at 11:04:07AM -0400, Jean Delvare wrote:
> > > > > * Removal code path is untested, as I have never been able to unload
> > > > > the thermal_sys module on any of my systems. Something is pinning it
> > > > > and I have no idea what it is.
> > > > > 
> > > > Doesn't lsmod show the culprit ?
> > > 
> > > No, it's not a module dependency. The reference counter is set to 1,
> 
> Sorry I realize I have been inaccurate. thermal_sys indeed depends on
> the processor module, and that's what prevents me from unloading it.
> It's the processor module which has a reference count of 1, and no
> dependency, so I have no idea how I could unload it.
> 
You mean the ACPI processor driver ? This comment might explain it:

/*
 * We keep the driver loaded even when ACPI is not running.
 * This is needed for the powernow-k8 driver, that works even without
 * ACPI, but needs symbols from this driver
 */

> > > so somewhere in the kernel something is taking a reference to the
> > > module and won't release it. I wish this was better instrumented so
> > > that it would be possible to know who is doing that.
> > 
> > The most likely culprit seems to be acpi.
> 
> I'm not sure. I don't see any relevant call to try_module_get under
> drivers/acpi, and I'm not aware of any other way to increase the
> reference count.
> 
What happens if the calling code (such as, in my case here, the acpi
video code) gets built into the kernel ? Would that force the module to
be and remain loaded ?

Guenter

Re: [PATCH v2 3/3] thermal: Make THERMAL_HWMON implementation fully internal

[Jean Delvare]

Hi Guenter,

On Tue, 26 Apr 2011 14:00:31 -0700, Guenter Roeck wrote:
> On Tue, 2011-04-26 at 15:39 -0400, Jean Delvare wrote:
> > Sorry I realize I have been inaccurate. thermal_sys indeed depends on
> > the processor module, and that's what prevents me from unloading it.
> > It's the processor module which has a reference count of 1, and no
> > dependency, so I have no idea how I could unload it.
> > 
> You mean the ACPI processor driver ? This comment might explain it:
> 
> /*
>  * We keep the driver loaded even when ACPI is not running.
>  * This is needed for the powernow-k8 driver, that works even without
>  * ACPI, but needs symbols from this driver
>  */

I doubt it. I don't have powernow-k8 loaded on the affected systems.
And if I did, that would be a regular inter-module dependency that
would be listed by lsmod.

> > (...)
> > I'm not sure. I don't see any relevant call to try_module_get under
> > drivers/acpi, and I'm not aware of any other way to increase the
> > reference count.
> > 
> What happens if the calling code (such as, in my case here, the acpi
> video code) gets built into the kernel ? Would that force the module to
> be and remain loaded ?

For regular inter-module dependencies, that's not even possible. You
can't build into the kernel a driver which depends on a symbol exported
by a driver which is built as a module. It will break at link time.

For reference counts increased by try_module_get(), it is possible, but
that doesn't necessarily make a difference from the all-modules case:
the reference count can be increased at any time, not only during
driver initialization, so the corresponding module_put doesn't
necessarily happen during module unloading (which indeed never happens
for a built-in driver.)

I tried booting in initlevel 1, but it didn't help, the reference count
of module processor is stuck to 1. So it's not user-space causing it...
it's something in the kernel itself. But I really don't have the time
to investigate this further, especially when I have no idea where to
look next.

-- 
Jean Delvare