[PATCH -mm 0/5] b43: Fix suspend/resume deadlock

[PATCH -mm 0/5] b43: Fix suspend/resume deadlock

[Rafael J. Wysocki]

Hi,

The following series of patches is intended to fix the suspend/resume deadlock
occuring as a result of unregistering device objects, locked by the PM core,
during suspend/resume cycles by the b43 driver.

In short, the b43 driver is modified to avoid unregistering device objects
during suspend/resume cycles except for the resume code path, in which the
devices are unregistered using the recently introduced suspend-safe method.
For this purpose, it is necessary to introduce the possibility to safely remove
misc devices, leds classdevs and hwrng devices during suspend/resume cycles
(patches 2/5, 4/5, 3/5, respectively).

Please consider for applying.

Thanks,
Rafael

[PATCH -mm 1/5] PM: Export device_pm_schedule_removal

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Move the declaration of device_pm_schedule_removal() to device.h
and make it exported, as it will be used directly by some drivers
for unregistering device objects during suspend/resume cycles in a
safe way.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 drivers/base/power/main.c  |    1 +
 drivers/base/power/power.h |    1 -
 include/linux/device.h     |    6 ++++++
 3 files changed, 7 insertions(+), 1 deletion(-)

Index: linux-2.6.24-rc8-mm1/drivers/base/power/main.c
===================================================================
--- linux-2.6.24-rc8-mm1.orig/drivers/base/power/main.c
+++ linux-2.6.24-rc8-mm1/drivers/base/power/main.c
@@ -129,6 +129,7 @@ void device_pm_schedule_removal(struct d
 	list_move_tail(&dev->power.entry, &dpm_destroy);
 	mutex_unlock(&dpm_list_mtx);
 }
+EXPORT_SYMBOL_GPL(device_pm_schedule_removal);
 
 /**
  *	pm_sleep_lock - mutual exclusion for registration and suspend
Index: linux-2.6.24-rc8-mm1/include/linux/device.h
===================================================================
--- linux-2.6.24-rc8-mm1.orig/include/linux/device.h
+++ linux-2.6.24-rc8-mm1/include/linux/device.h
@@ -532,11 +532,17 @@ extern struct device *device_create(stru
 extern void device_destroy(struct class *cls, dev_t devt);
 #ifdef CONFIG_PM_SLEEP
 extern void destroy_suspended_device(struct class *cls, dev_t devt);
+extern void device_pm_schedule_removal(struct device *);
 #else /* !CONFIG_PM_SLEEP */
 static inline void destroy_suspended_device(struct class *cls, dev_t devt)
 {
 	device_destroy(cls, devt);
 }
+
+static inline void device_pm_schedule_removal(struct device *dev)
+{
+	device_unregister(dev);
+}
 #endif /* !CONFIG_PM_SLEEP */
 
 /*
Index: linux-2.6.24-rc8-mm1/drivers/base/power/power.h
===================================================================
--- linux-2.6.24-rc8-mm1.orig/drivers/base/power/power.h
+++ linux-2.6.24-rc8-mm1/drivers/base/power/power.h
@@ -13,7 +13,6 @@ static inline struct device *to_device(s
 
 extern void device_pm_add(struct device *);
 extern void device_pm_remove(struct device *);
-extern void device_pm_schedule_removal(struct device *);
 extern int pm_sleep_lock(void);
 extern void pm_sleep_unlock(void);
 

Re: [PATCH -mm 1/5] PM: Export device_pm_schedule_removal

[Pavel Machek]

On Fri 2008-01-25 01:30:25, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> 
> Move the declaration of device_pm_schedule_removal() to device.h
> and make it exported, as it will be used directly by some drivers
> for unregistering device objects during suspend/resume cycles in a
> safe way.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

ACK.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

patch pm-export-device_pm_schedule_removal.patch added to gregkh-2.6 tree

[gregkh]

This is a note to let you know that I've just added the patch titled

     Subject: PM: Export device_pm_schedule_removal

to my gregkh-2.6 tree.  Its filename is

     pm-export-device_pm_schedule_removal.patch

This tree can be found at 
    http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/


>From rjw@sisk.pl  Mon Jan 28 08:57:01 2008
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Date: Fri, 25 Jan 2008 01:30:25 +0100
Subject: PM: Export device_pm_schedule_removal
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michael Buesch <mb@bu3sch.de>, pm list <linux-pm@lists.linux-foundation.org>, Alan Stern <stern@rowland.harvard.edu>, Len Brown <lenb@kernel.org>, LKML <linux-kernel@vger.kernel.org>, Pavel Machek <pavel@ucw.cz>, bcm43xx-dev@lists.berlios.de, Alessandro Rubini <rubini@ipvvis.unipv.it>, Richard Purdie <rpurdie@rpsys.net>, Greg KH <greg@kroah.com>
Message-ID: <200801250130.26591.rjw@sisk.pl>
Content-Disposition: inline


From: Rafael J. Wysocki <rjw@sisk.pl>

Move the declaration of device_pm_schedule_removal() to device.h
and make it exported, as it will be used directly by some drivers
for unregistering device objects during suspend/resume cycles in a
safe way.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/base/power/main.c  |    1 +
 drivers/base/power/power.h |    1 -
 include/linux/device.h     |    6 ++++++
 3 files changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -129,6 +129,7 @@ void device_pm_schedule_removal(struct d
 	list_move_tail(&dev->power.entry, &dpm_destroy);
 	mutex_unlock(&dpm_list_mtx);
 }
+EXPORT_SYMBOL_GPL(device_pm_schedule_removal);
 
 /**
  *	pm_sleep_lock - mutual exclusion for registration and suspend
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -13,7 +13,6 @@ static inline struct device *to_device(s
 
 extern void device_pm_add(struct device *);
 extern void device_pm_remove(struct device *);
-extern void device_pm_schedule_removal(struct device *);
 extern int pm_sleep_lock(void);
 extern void pm_sleep_unlock(void);
 
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -534,11 +534,17 @@ extern struct device *device_create(stru
 extern void device_destroy(struct class *cls, dev_t devt);
 #ifdef CONFIG_PM_SLEEP
 extern void destroy_suspended_device(struct class *cls, dev_t devt);
+extern void device_pm_schedule_removal(struct device *);
 #else /* !CONFIG_PM_SLEEP */
 static inline void destroy_suspended_device(struct class *cls, dev_t devt)
 {
 	device_destroy(cls, devt);
 }
+
+static inline void device_pm_schedule_removal(struct device *dev)
+{
+	device_unregister(dev);
+}
 #endif /* !CONFIG_PM_SLEEP */
 
 /*


Patches currently in gregkh-2.6 which might be from rjw@sisk.pl are

driver/pm-export-device_pm_schedule_removal.patch

[PATCH -mm 2/5] Misc: Add possibility to remove misc devices during suspend/resume

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Make it possible to unregister a misc device object in a safe way
during a suspend/resume cycle.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 drivers/char/misc.c        |   13 +++++++++----
 include/linux/miscdevice.h |   10 +++++++++-
 2 files changed, 18 insertions(+), 5 deletions(-)

Index: linux-2.6.24-rc8-mm1/include/linux/miscdevice.h
===================================================================
--- linux-2.6.24-rc8-mm1.orig/include/linux/miscdevice.h
+++ linux-2.6.24-rc8-mm1/include/linux/miscdevice.h
@@ -43,7 +43,15 @@ struct miscdevice  {
 };
 
 extern int misc_register(struct miscdevice * misc);
-extern int misc_deregister(struct miscdevice * misc);
+extern int __misc_deregister(struct miscdevice *misc, bool suspended);
+static inline int misc_deregister(struct miscdevice *misc)
+{
+	return __misc_deregister(misc, false);
+}
+static inline int misc_deregister_suspended(struct miscdevice *misc)
+{
+	return __misc_deregister(misc, true);
+}
 
 #define MODULE_ALIAS_MISCDEV(minor)				\
 	MODULE_ALIAS("char-major-" __stringify(MISC_MAJOR)	\
Index: linux-2.6.24-rc8-mm1/drivers/char/misc.c
===================================================================
--- linux-2.6.24-rc8-mm1.orig/drivers/char/misc.c
+++ linux-2.6.24-rc8-mm1/drivers/char/misc.c
@@ -232,8 +232,9 @@ int misc_register(struct miscdevice * mi
 }
 
 /**
- *	misc_deregister - unregister a miscellaneous device
+ *	__misc_deregister - unregister a miscellaneous device
  *	@misc: device to unregister
+ *	@suspended: to be set if the function is used during suspend/resume
  *
  *	Unregister a miscellaneous device that was previously
  *	successfully registered with misc_register(). Success
@@ -241,7 +242,7 @@ int misc_register(struct miscdevice * mi
  *	indicates an error.
  */
 
-int misc_deregister(struct miscdevice * misc)
+int __misc_deregister(struct miscdevice *misc, bool suspended)
 {
 	int i = misc->minor;
 
@@ -250,7 +251,11 @@ int misc_deregister(struct miscdevice * 
 
 	mutex_lock(&misc_mtx);
 	list_del(&misc->list);
-	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
+	if (suspended)
+		destroy_suspended_device(misc_class,
+					MKDEV(MISC_MAJOR, misc->minor));
+	else
+		device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
 	if (i < DYNAMIC_MINORS && i>0) {
 		misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
 	}
@@ -259,7 +264,7 @@ int misc_deregister(struct miscdevice * 
 }
 
 EXPORT_SYMBOL(misc_register);
-EXPORT_SYMBOL(misc_deregister);
+EXPORT_SYMBOL(__misc_deregister);
 
 static int __init misc_init(void)
 {

[PATCH -mm 3/5] HWRNG: Add possibility to remove hwrng devices during suspend/resume

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Make it possible to unregister a Hardware Random Number Generator
device object in a safe way during a suspend/resume cycle.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Michael Buesch <mb@bu3sch.de>
---
 drivers/char/hw_random/core.c |   10 +++++-----
 include/linux/hw_random.h     |   10 +++++++++-
 2 files changed, 14 insertions(+), 6 deletions(-)

Index: linux-2.6.24-rc8-mm1/drivers/char/hw_random/core.c
===================================================================
--- linux-2.6.24-rc8-mm1.orig/drivers/char/hw_random/core.c
+++ linux-2.6.24-rc8-mm1/drivers/char/hw_random/core.c
@@ -234,11 +234,11 @@ static DEVICE_ATTR(rng_available, S_IRUG
 		   NULL);
 
 
-static void unregister_miscdev(void)
+static void unregister_miscdev(bool suspended)
 {
 	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
 	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
-	misc_deregister(&rng_miscdev);
+	__misc_deregister(&rng_miscdev, suspended);
 }
 
 static int register_miscdev(void)
@@ -313,7 +313,7 @@ out:
 }
 EXPORT_SYMBOL_GPL(hwrng_register);
 
-void hwrng_unregister(struct hwrng *rng)
+void __hwrng_unregister(struct hwrng *rng, bool suspended)
 {
 	int err;
 
@@ -332,11 +332,11 @@ void hwrng_unregister(struct hwrng *rng)
 		}
 	}
 	if (list_empty(&rng_list))
-		unregister_miscdev();
+		unregister_miscdev(suspended);
 
 	mutex_unlock(&rng_mutex);
 }
-EXPORT_SYMBOL_GPL(hwrng_unregister);
+EXPORT_SYMBOL_GPL(__hwrng_unregister);
 
 
 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
Index: linux-2.6.24-rc8-mm1/include/linux/hw_random.h
===================================================================
--- linux-2.6.24-rc8-mm1.orig/include/linux/hw_random.h
+++ linux-2.6.24-rc8-mm1/include/linux/hw_random.h
@@ -44,7 +44,15 @@ struct hwrng {
 /** Register a new Hardware Random Number Generator driver. */
 extern int hwrng_register(struct hwrng *rng);
 /** Unregister a Hardware Random Number Generator driver. */
-extern void hwrng_unregister(struct hwrng *rng);
+extern void __hwrng_unregister(struct hwrng *rng, bool suspended);
+static inline void hwrng_unregister(struct hwrng *rng)
+{
+	__hwrng_unregister(rng, false);
+}
+static inline void hwrng_unregister_suspended(struct hwrng *rng)
+{
+	__hwrng_unregister(rng, true);
+}
 
 #endif /* __KERNEL__ */
 #endif /* LINUX_HWRANDOM_H_ */

[PATCH -mm 4/5] Leds: Add possibility to remove leds classdevs during suspend/resume

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Make it possible to unregister a led classdev object in a safe way
during a suspend/resume cycle.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 drivers/leds/led-class.c |   13 +++++++++----
 include/linux/leds.h     |   10 +++++++++-
 2 files changed, 18 insertions(+), 5 deletions(-)

Index: linux-2.6.24-rc8-mm1/drivers/leds/led-class.c
===================================================================
--- linux-2.6.24-rc8-mm1.orig/drivers/leds/led-class.c
+++ linux-2.6.24-rc8-mm1/drivers/leds/led-class.c
@@ -137,12 +137,14 @@ err_out:
 EXPORT_SYMBOL_GPL(led_classdev_register);
 
 /**
- * led_classdev_unregister - unregisters a object of led_properties class.
+ * __led_classdev_unregister - unregisters a object of led_properties class.
  * @led_cdev: the led device to unregister
+ * @suspended: indicates whether system-wide suspend or resume is in progress
  *
  * Unregisters a previously registered via led_classdev_register object.
  */
-void led_classdev_unregister(struct led_classdev *led_cdev)
+void __led_classdev_unregister(struct led_classdev *led_cdev,
+				      bool suspended)
 {
 	device_remove_file(led_cdev->dev, &dev_attr_brightness);
 #ifdef CONFIG_LEDS_TRIGGERS
@@ -153,13 +155,16 @@ void led_classdev_unregister(struct led_
 	up_write(&led_cdev->trigger_lock);
 #endif
 
-	device_unregister(led_cdev->dev);
+	if (suspended)
+		device_pm_schedule_removal(led_cdev->dev);
+	else
+		device_unregister(led_cdev->dev);
 
 	down_write(&leds_list_lock);
 	list_del(&led_cdev->node);
 	up_write(&leds_list_lock);
 }
-EXPORT_SYMBOL_GPL(led_classdev_unregister);
+EXPORT_SYMBOL_GPL(__led_classdev_unregister);
 
 static int __init leds_init(void)
 {
Index: linux-2.6.24-rc8-mm1/include/linux/leds.h
===================================================================
--- linux-2.6.24-rc8-mm1.orig/include/linux/leds.h
+++ linux-2.6.24-rc8-mm1/include/linux/leds.h
@@ -59,7 +59,15 @@ struct led_classdev {
 
 extern int led_classdev_register(struct device *parent,
 				 struct led_classdev *led_cdev);
-extern void led_classdev_unregister(struct led_classdev *led_cdev);
+extern void __led_classdev_unregister(struct led_classdev *led_cdev, bool sus);
+static inline void led_classdev_unregister(struct led_classdev *lcd)
+{
+	__led_classdev_unregister(lcd, false);
+}
+static inline void led_classdev_unregister_suspended(struct led_classdev *lcd)
+{
+	__led_classdev_unregister(lcd, true);
+}
 extern void led_classdev_suspend(struct led_classdev *led_cdev);
 extern void led_classdev_resume(struct led_classdev *led_cdev);
 

[PATCH -mm 5/5] b43: Avoid unregistering device objects during suspend

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Modify the b43 driver to avoid deadlocking suspend and resume,
which happens as a result of attempting to unregister device objects
locked by the PM core during suspend/resume cycles.  Also, make it
use a suspend-safe method of unregistering device object in the
resume error path.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Michael Buesch <mb@bu3sch.de>
---
 drivers/net/wireless/b43/b43.h  |    1 +
 drivers/net/wireless/b43/leds.c |    5 ++++-
 drivers/net/wireless/b43/main.c |   25 ++++++++++++++++---------
 3 files changed, 21 insertions(+), 10 deletions(-)

Index: linux-2.6.24-rc8-mm1/drivers/net/wireless/b43/b43.h
===================================================================
--- linux-2.6.24-rc8-mm1.orig/drivers/net/wireless/b43/b43.h
+++ linux-2.6.24-rc8-mm1/drivers/net/wireless/b43/b43.h
@@ -706,6 +706,7 @@ struct b43_wldev {
 	bool short_preamble;	/* TRUE, if short preamble is enabled. */
 	bool short_slot;	/* TRUE, if short slot timing is enabled. */
 	bool radio_hw_enable;	/* saved state of radio hardware enabled state */
+	bool suspend_in_progress;	/* TRUE, if we are in a suspend/resume cycle */
 
 	/* PHY/Radio device. */
 	struct b43_phy phy;
Index: linux-2.6.24-rc8-mm1/drivers/net/wireless/b43/main.c
===================================================================
--- linux-2.6.24-rc8-mm1.orig/drivers/net/wireless/b43/main.c
+++ linux-2.6.24-rc8-mm1/drivers/net/wireless/b43/main.c
@@ -2470,10 +2470,10 @@ static int b43_rng_read(struct hwrng *rn
 	return (sizeof(u16));
 }
 
-static void b43_rng_exit(struct b43_wl *wl)
+static void b43_rng_exit(struct b43_wl *wl, bool suspended)
 {
 	if (wl->rng_initialized)
-		hwrng_unregister(&wl->rng);
+		__hwrng_unregister(&wl->rng, suspended);
 }
 
 static int b43_rng_init(struct b43_wl *wl)
@@ -3298,8 +3298,10 @@ static void b43_wireless_core_exit(struc
 		return;
 	b43_set_status(dev, B43_STAT_UNINIT);
 
-	b43_leds_exit(dev);
-	b43_rng_exit(dev->wl);
+	if (!dev->suspend_in_progress) {
+		b43_leds_exit(dev);
+		b43_rng_exit(dev->wl, false);
+	}
 	b43_pio_free(dev);
 	b43_dma_free(dev);
 	b43_chip_exit(dev);
@@ -3420,11 +3422,13 @@ static int b43_wireless_core_init(struct
 	memset(wl->mac_addr, 0, ETH_ALEN);
 	b43_upload_card_macaddress(dev);
 	b43_security_init(dev);
-	b43_rng_init(wl);
+	if (!dev->suspend_in_progress)
+		b43_rng_init(wl);
 
 	b43_set_status(dev, B43_STAT_INITIALIZED);
 
-	b43_leds_init(dev);
+	if (!dev->suspend_in_progress)
+		b43_leds_init(dev);
 out:
 	return err;
 
@@ -4024,6 +4028,7 @@ static int b43_suspend(struct ssb_device
 	b43dbg(wl, "Suspending...\n");
 
 	mutex_lock(&wl->mutex);
+	wldev->suspend_in_progress = true;
 	wldev->suspend_init_status = b43_status(wldev);
 	if (wldev->suspend_init_status >= B43_STAT_STARTED)
 		b43_wireless_core_stop(wldev);
@@ -4055,15 +4060,17 @@ static int b43_resume(struct ssb_device 
 	if (wldev->suspend_init_status >= B43_STAT_STARTED) {
 		err = b43_wireless_core_start(wldev);
 		if (err) {
+			b43_leds_exit(wldev);
+			b43_rng_exit(wldev->wl, true);
 			b43_wireless_core_exit(wldev);
 			b43err(wl, "Resume failed at core start\n");
 			goto out;
 		}
 	}
-	mutex_unlock(&wl->mutex);
-
 	b43dbg(wl, "Device resumed.\n");
-      out:
+ out:
+	wldev->suspend_in_progress = false;
+	mutex_unlock(&wl->mutex);
 	return err;
 }
 
Index: linux-2.6.24-rc8-mm1/drivers/net/wireless/b43/leds.c
===================================================================
--- linux-2.6.24-rc8-mm1.orig/drivers/net/wireless/b43/leds.c
+++ linux-2.6.24-rc8-mm1/drivers/net/wireless/b43/leds.c
@@ -116,7 +116,10 @@ static void b43_unregister_led(struct b4
 {
 	if (!led->dev)
 		return;
-	led_classdev_unregister(&led->led_dev);
+	if (led->dev->suspend_in_progress)
+		led_classdev_unregister_suspended(&led->led_dev);
+	else
+		led_classdev_unregister(&led->led_dev);
 	b43_led_turn_off(led->dev, led->index, led->activelow);
 	led->dev = NULL;
 }

Re: [PATCH -mm 5/5] b43: Avoid unregistering device objects during suspend

[Pavel Machek]

On Fri 2008-01-25 01:37:33, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> 
> Modify the b43 driver to avoid deadlocking suspend and resume,
> which happens as a result of attempting to unregister device objects
> locked by the PM core during suspend/resume cycles.  Also, make it
> use a suspend-safe method of unregistering device object in the
> resume error path.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> Acked-by: Michael Buesch <mb@bu3sch.de>

Maybe we should have global suspend_in_progress (or maybe system_state
== suspending?) and automatically switch to schedule_removal() while
it is set?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH -mm 5/5] b43: Avoid unregistering device objects during suspend

[Michael Buesch]

On Friday 25 January 2008 08:47:46 Pavel Machek wrote:
> On Fri 2008-01-25 01:37:33, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> > 
> > Modify the b43 driver to avoid deadlocking suspend and resume,
> > which happens as a result of attempting to unregister device objects
> > locked by the PM core during suspend/resume cycles.  Also, make it
> > use a suspend-safe method of unregistering device object in the
> > resume error path.
> > 
> > Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> > Acked-by: Michael Buesch <mb@bu3sch.de>
> 
> Maybe we should have global suspend_in_progress (or maybe system_state
> == suspending?) and automatically switch to schedule_removal() while
> it is set?
> 

That would be great, from my perspective :)

-- 
Greetings Michael.

Re: [PATCH -mm 5/5] b43: Avoid unregistering device objects during suspend

[Rafael J. Wysocki]

On Friday, 25 of January 2008, Michael Buesch wrote:
> On Friday 25 January 2008 08:47:46 Pavel Machek wrote:
> > On Fri 2008-01-25 01:37:33, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rjw@sisk.pl>
> > > 
> > > Modify the b43 driver to avoid deadlocking suspend and resume,
> > > which happens as a result of attempting to unregister device objects
> > > locked by the PM core during suspend/resume cycles.  Also, make it
> > > use a suspend-safe method of unregistering device object in the
> > > resume error path.
> > > 
> > > Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> > > Acked-by: Michael Buesch <mb@bu3sch.de>
> > 
> > Maybe we should have global suspend_in_progress (or maybe system_state
> > == suspending?) and automatically switch to schedule_removal() while
> > it is set?
> > 
> 
> That would be great, from my perspective :)

Let's see how many drivers are going to need that.  If there's more than a
couple, it will certainly make sense to have a global variable like this.

Thanks,
Rafael

Re: [PATCH -mm 5/5] b43: Avoid unregistering device objects during suspend

[Alan Stern]

On Fri, 25 Jan 2008, Pavel Machek wrote:

> Maybe we should have global suspend_in_progress (or maybe system_state
> == suspending?) and automatically switch to schedule_removal() while
> it is set?

:-)  There was a time a couple of years ago when you objected violently 
to the mere suggestion of such a global variable!

It's not a bad idea IMO.  But if it does get implemented, a global
function would be better than a global variable.  It would provide
more encapsulation.

Alan Stern

Re: [PATCH -mm 5/5] b43: Avoid unregistering device objects during suspend

[Pavel Machek]

On Fri 2008-01-25 09:58:00, Alan Stern wrote:
> On Fri, 25 Jan 2008, Pavel Machek wrote:
> 
> > Maybe we should have global suspend_in_progress (or maybe system_state
> > == suspending?) and automatically switch to schedule_removal() while
> > it is set?
> 
> :-)  There was a time a couple of years ago when you objected violently 
> to the mere suggestion of such a global variable!

Lets say I was young at stupid...? ;-).

> It's not a bad idea IMO.  But if it does get implemented, a global
> function would be better than a global variable.  It would provide
> more encapsulation.

Agreed.
								Pavel

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