Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | Re: [Bug 10030] Suspend doesn't work when SD card is inserted | Date | Thu, 21 Feb 2008 01:02:11 +0100 |
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On Wednesday, 20 of February 2008, Alan Stern wrote: > On Wed, 20 Feb 2008, Rafael J. Wysocki wrote: > > > Well, below is an uncompiled and untested but illustrating the idea that > > might allow people not to bother with device_pm_schedule_removal() > > explicitly and can fix the issue at hand. > > > > [There are some cases that need handling and are not covered here.] > > > > Please have a look. > > > > Thanks, > > Rafael > > > +static struct task_struct *suspending_task; > > +static DEFINE_MUTEX(suspending_task_mtx); > > I suspect you don't really need this mutex. > > > +bool in_suspend_context(void) > > +{ > > + bool result; > > + > > + mutex_lock(&suspending_task_mtx); > > + result = (suspending_task == current); > > + mutex_unlock(&suspending_task_mtx); > > + return result; > > +} > > If suspending_task == current then you are guaranteed to be serialized, > because everything a single task does is serial.
As I said before (but that doesn't seem to reach the list, so I'm repeating), this is to protect other tasks from reading an inconsistent value of suspending_task in case they attempt to remove a device concurrently with respect to us.
While this is not likely to happen right now, because of the freezer, it may very well happen when the freezer is finally removed.
> > @@ -1162,7 +1162,10 @@ void device_destroy(struct class *class, > > dev = class_find_device(class, &devt, __match_devt); > > if (dev) { > > put_device(dev); > > - device_unregister(dev); > > + if (in_suspend_context()) > > + device_pm_schedule_removal(dev); > > + else > > + device_unregister(dev); > > } > > } > > But what about device_del()? Can a similar change be made there?
Something like the patch below, perhaps? Again, untested, but compiled this time. :-)
Thanks, Rafael
--- drivers/base/core.c | 5 +++++ drivers/base/power/main.c | 22 ++++++++++++++++++++++ drivers/base/power/power.h | 5 +++++ 3 files changed, 32 insertions(+)
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 @@ -59,6 +59,26 @@ static DECLARE_RWSEM(pm_sleep_rwsem); int (*platform_enable_wakeup)(struct device *dev, int is_on); +static struct task_struct *suspending_task; +static DEFINE_MUTEX(suspending_task_mtx); + +bool in_suspend_context(void) +{ + bool result; + + mutex_lock(&suspending_task_mtx); + result = (suspending_task == current); + mutex_unlock(&suspending_task_mtx); + return result; +} + +static void set_suspending_task(struct task_struct *task) +{ + mutex_lock(&suspending_task_mtx); + suspending_task = task; + mutex_unlock(&suspending_task_mtx); +} + /** * device_pm_add - add a device to the list of active devices * @dev: Device to be added to the list @@ -272,6 +292,7 @@ static void dpm_resume(void) mutex_lock(&dpm_list_mtx); } mutex_unlock(&dpm_list_mtx); + set_suspending_task(NULL); } /** @@ -460,6 +481,7 @@ static int dpm_suspend(pm_message_t stat { int error = 0; + set_suspending_task(current); mutex_lock(&dpm_list_mtx); while (!list_empty(&dpm_locked)) { struct list_head *entry = dpm_locked.prev; Index: linux-2.6/drivers/base/core.c =================================================================== --- linux-2.6.orig/drivers/base/core.c +++ linux-2.6/drivers/base/core.c @@ -929,6 +929,11 @@ void device_del(struct device *dev) struct device *parent = dev->parent; struct class_interface *class_intf; + if (in_suspend_context()) { + get_device(dev); + device_pm_schedule_removal(dev); + return; + } device_pm_remove(dev); if (parent) klist_del(&dev->knode_parent); Index: linux-2.6/drivers/base/power/power.h =================================================================== --- linux-2.6.orig/drivers/base/power/power.h +++ linux-2.6/drivers/base/power/power.h @@ -11,6 +11,7 @@ static inline struct device *to_device(s return container_of(entry, struct device, power.entry); } +extern bool in_suspend_context(void); extern void device_pm_add(struct device *); extern void device_pm_remove(struct device *); extern int pm_sleep_lock(void); @@ -18,6 +19,10 @@ extern void pm_sleep_unlock(void); #else /* CONFIG_PM_SLEEP */ +static inline bool in_suspend_context(void) +{ + return false; +} static inline void device_pm_add(struct device *dev) {
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