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Date: Sat, 23 Feb 2008 21:43:31 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Julian Blake Kongslie <jblake@...wallhack.org>
Cc: linux-kernel@...r.kernel.org
Subject: Re: Hang on suspend
On Thursday, 21 of February 2008, Julian Blake Kongslie wrote:
> I'm getting a hang at suspend on 2.6.25-rc2. Booting with
> no_console_suspend let me catch the error, which I photographed and
> transcribed (hopefully without error) below.
>
> This is a Lenovo Thinkpad T43p.
>
> I've attached my config and a partial dmesg (this machine generates a
> lot of messages at boot, and overfills the buffer before klogd gets to
> it).
Can you please apply the appened patch and retest?
Thanks,
Rafael
---
drivers/base/power/main.c | 84 ++--------------------------------------------
1 file changed, 4 insertions(+), 80 deletions(-)
Index: linux-2.6/drivers/base/power/main.c
===================================================================
--- linux-2.6.orig/drivers/base/power/main.c
+++ linux-2.6/drivers/base/power/main.c
@@ -48,7 +48,6 @@
*/
LIST_HEAD(dpm_active);
-static LIST_HEAD(dpm_locked);
static LIST_HEAD(dpm_off);
static LIST_HEAD(dpm_off_irq);
static LIST_HEAD(dpm_destroy);
@@ -81,28 +80,6 @@ void device_pm_add(struct device *dev)
*/
void device_pm_remove(struct device *dev)
{
- /*
- * If this function is called during a suspend, it will be blocked,
- * because we're holding the device's semaphore at that time, which may
- * lead to a deadlock. In that case we want to print a warning.
- * However, it may also be called by unregister_dropped_devices() with
- * the device's semaphore released, in which case the warning should
- * not be printed.
- */
- if (down_trylock(&dev->sem)) {
- if (down_read_trylock(&pm_sleep_rwsem)) {
- /* No suspend in progress, wait on dev->sem */
- down(&dev->sem);
- up_read(&pm_sleep_rwsem);
- } else {
- /* Suspend in progress, we may deadlock */
- dev_warn(dev, "Suspicious %s during suspend\n",
- __FUNCTION__);
- dump_stack();
- /* The user has been warned ... */
- down(&dev->sem);
- }
- }
pr_debug("PM: Removing info for %s:%s\n",
dev->bus ? dev->bus->name : "No Bus",
kobject_name(&dev->kobj));
@@ -110,7 +87,6 @@ void device_pm_remove(struct device *dev
dpm_sysfs_remove(dev);
list_del_init(&dev->power.entry);
mutex_unlock(&dpm_list_mtx);
- up(&dev->sem);
}
/**
@@ -266,7 +242,7 @@ static void dpm_resume(void)
struct list_head *entry = dpm_off.next;
struct device *dev = to_device(entry);
- list_move_tail(entry, &dpm_locked);
+ list_move_tail(entry, &dpm_active);
mutex_unlock(&dpm_list_mtx);
resume_device(dev);
mutex_lock(&dpm_list_mtx);
@@ -275,25 +251,6 @@ static void dpm_resume(void)
}
/**
- * unlock_all_devices - Release each device's semaphore
- *
- * Go through the dpm_off list. Put each device on the dpm_active
- * list and unlock it.
- */
-static void unlock_all_devices(void)
-{
- mutex_lock(&dpm_list_mtx);
- while (!list_empty(&dpm_locked)) {
- struct list_head *entry = dpm_locked.prev;
- struct device *dev = to_device(entry);
-
- list_move(entry, &dpm_active);
- up(&dev->sem);
- }
- mutex_unlock(&dpm_list_mtx);
-}
-
-/**
* unregister_dropped_devices - Unregister devices scheduled for removal
*
* Unregister all devices on the dpm_destroy list.
@@ -305,7 +262,6 @@ static void unregister_dropped_devices(v
struct list_head *entry = dpm_destroy.next;
struct device *dev = to_device(entry);
- up(&dev->sem);
mutex_unlock(&dpm_list_mtx);
/* This also removes the device from the list */
device_unregister(dev);
@@ -324,7 +280,6 @@ void device_resume(void)
{
might_sleep();
dpm_resume();
- unlock_all_devices();
unregister_dropped_devices();
up_write(&pm_sleep_rwsem);
}
@@ -461,8 +416,8 @@ static int dpm_suspend(pm_message_t stat
int error = 0;
mutex_lock(&dpm_list_mtx);
- while (!list_empty(&dpm_locked)) {
- struct list_head *entry = dpm_locked.prev;
+ while (!list_empty(&dpm_active)) {
+ struct list_head *entry = dpm_active.prev;
struct device *dev = to_device(entry);
list_del_init(&dev->power.entry);
@@ -478,7 +433,7 @@ static int dpm_suspend(pm_message_t stat
""));
mutex_lock(&dpm_list_mtx);
if (list_empty(&dev->power.entry))
- list_add(&dev->power.entry, &dpm_locked);
+ list_add_tail(&dev->power.entry, &dpm_active);
break;
}
mutex_lock(&dpm_list_mtx);
@@ -491,36 +446,6 @@ static int dpm_suspend(pm_message_t stat
}
/**
- * lock_all_devices - Acquire every device's semaphore
- *
- * Go through the dpm_active list. Carefully lock each device's
- * semaphore and put it in on the dpm_locked list.
- */
-static void lock_all_devices(void)
-{
- mutex_lock(&dpm_list_mtx);
- while (!list_empty(&dpm_active)) {
- struct list_head *entry = dpm_active.next;
- struct device *dev = to_device(entry);
-
- /* Required locking order is dev->sem first,
- * then dpm_list_mutex. Hence this awkward code.
- */
- get_device(dev);
- mutex_unlock(&dpm_list_mtx);
- down(&dev->sem);
- mutex_lock(&dpm_list_mtx);
-
- if (list_empty(entry))
- up(&dev->sem); /* Device was removed */
- else
- list_move_tail(entry, &dpm_locked);
- put_device(dev);
- }
- mutex_unlock(&dpm_list_mtx);
-}
-
-/**
* device_suspend - Save state and stop all devices in system.
* @state: new power management state
*
@@ -533,7 +458,6 @@ int device_suspend(pm_message_t state)
might_sleep();
down_write(&pm_sleep_rwsem);
- lock_all_devices();
error = dpm_suspend(state);
if (error)
device_resume();
--
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