Commit 32bdfac5 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PM: Do not hold dpm_list_mtx while disabling/enabling nonboot CPUs 

We shouldn't hold dpm_list_mtx while executing
[disable|enable]_nonboot_cpus(), because theoretically this may lead
to a deadlock as shown by the following example (provided by Johannes
Berg):

CPU 3       CPU 2                     CPU 1
                                      suspend/hibernate
            something:
            rtnl_lock()               device_pm_lock()
                                       -> mutex_lock(&dpm_list_mtx)

            mutex_lock(&dpm_list_mtx)

linkwatch_work
 -> rtnl_lock()
                                      disable_nonboot_cpus()
                                       -> flush CPU 3 workqueue

Fortunately, device drivers are supposed to stop any activities that
might lead to the registration of new device objects way before
disable_nonboot_cpus() is called, so it shouldn't be necessary to
hold dpm_list_mtx over the entire late part of device suspend and
early part of device resume.

Thus, during the late suspend and the early resume of devices acquire
dpm_list_mtx only when dpm_list is going to be traversed and release
it right after that.

This patch is reported to fix the regressions tracked as
http://bugzilla.kernel.org/show_bug.cgi?id=13245

.

Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Reported-by: default avatarMiles Lane <miles.lane@gmail.com>
Tested-by: default avatarMing Lei <tom.leiming@gmail.com>
parent 59a3759d

drivers/base/power/main.c

+4 −0
Original line number Diff line number Diff line
@@ -357,6 +357,7 @@ static void dpm_power_up(pm_message_t state) 
{

	struct device *dev;



	mutex_lock(&dpm_list_mtx);

	list_for_each_entry(dev, &dpm_list, power.entry)

		if (dev->power.status > DPM_OFF) {

			int error;
@@ -366,6 +367,7 @@ static void dpm_power_up(pm_message_t state) 
			if (error)

				pm_dev_err(dev, state, " early", error);

		}

	mutex_unlock(&dpm_list_mtx);

}



/**
@@ -614,6 +616,7 @@ int device_power_down(pm_message_t state) 
	int error = 0;



	suspend_device_irqs();

	mutex_lock(&dpm_list_mtx);

	list_for_each_entry_reverse(dev, &dpm_list, power.entry) {

		error = suspend_device_noirq(dev, state);

		if (error) {
@@ -622,6 +625,7 @@ int device_power_down(pm_message_t state) 
		}

		dev->power.status = DPM_OFF_IRQ;

	}

	mutex_unlock(&dpm_list_mtx);

	if (error)

		device_power_up(resume_event(state));

	return error;

kernel/kexec.c

+0 −2
Original line number Diff line number Diff line
@@ -1451,7 +1451,6 @@ int kernel_kexec(void) 
		error = device_suspend(PMSG_FREEZE);

		if (error)

			goto Resume_console;

		device_pm_lock();

		/* At this point, device_suspend() has been called,

		 * but *not* device_power_down(). We *must*

		 * device_power_down() now.  Otherwise, drivers for
@@ -1489,7 +1488,6 @@ int kernel_kexec(void) 
		enable_nonboot_cpus();

		device_power_up(PMSG_RESTORE);

 Resume_devices:

		device_pm_unlock();

		device_resume(PMSG_RESTORE);

 Resume_console:

		resume_console();

kernel/power/disk.c

+3 −18
Original line number Diff line number Diff line
@@ -215,8 +215,6 @@ static int create_image(int platform_mode) 
	if (error)

		return error;



	device_pm_lock();



	/* At this point, device_suspend() has been called, but *not*

	 * device_power_down(). We *must* call device_power_down() now.

	 * Otherwise, drivers for some devices (e.g. interrupt controllers)
@@ -227,7 +225,7 @@ static int create_image(int platform_mode) 
	if (error) {

		printk(KERN_ERR "PM: Some devices failed to power down, "

			"aborting hibernation\n");

		goto Unlock;

		return error;

	}



	error = platform_pre_snapshot(platform_mode);
@@ -280,9 +278,6 @@ static int create_image(int platform_mode) 
	device_power_up(in_suspend ?

		(error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);



 Unlock:

	device_pm_unlock();



	return error;

}
@@ -344,13 +339,11 @@ static int resume_target_kernel(bool platform_mode) 
{

	int error;



	device_pm_lock();



	error = device_power_down(PMSG_QUIESCE);

	if (error) {

		printk(KERN_ERR "PM: Some devices failed to power down, "

			"aborting resume\n");

		goto Unlock;

		return error;

	}



	error = platform_pre_restore(platform_mode);
@@ -403,9 +396,6 @@ static int resume_target_kernel(bool platform_mode) 


	device_power_up(PMSG_RECOVER);



 Unlock:

	device_pm_unlock();



	return error;

}
@@ -464,11 +454,9 @@ int hibernation_platform_enter(void) 
		goto Resume_devices;

	}



	device_pm_lock();



	error = device_power_down(PMSG_HIBERNATE);

	if (error)

		goto Unlock;

		goto Resume_devices;



	error = hibernation_ops->prepare();

	if (error)
@@ -493,9 +481,6 @@ int hibernation_platform_enter(void) 


	device_power_up(PMSG_RESTORE);



 Unlock:

	device_pm_unlock();



 Resume_devices:

	entering_platform_hibernation = false;

	device_resume(PMSG_RESTORE);

kernel/power/main.c

+1 −6
Original line number Diff line number Diff line
@@ -289,12 +289,10 @@ static int suspend_enter(suspend_state_t state) 
{

	int error;



	device_pm_lock();



	if (suspend_ops->prepare) {

		error = suspend_ops->prepare();

		if (error)

			goto Done;

			return error;

	}



	error = device_power_down(PMSG_SUSPEND);
@@ -343,9 +341,6 @@ static int suspend_enter(suspend_state_t state) 
	if (suspend_ops->finish)

		suspend_ops->finish();



 Done:

	device_pm_unlock();



	return error;

}

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