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: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Miles Lane <miles.lane@gmail.com>
Tested-by: Ming Lei <tom.leiming@gmail.com>
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 69b4ddb..3e4bc69 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -357,6 +357,7 @@
{
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 @@
if (error)
pm_dev_err(dev, state, " early", error);
}
+ mutex_unlock(&dpm_list_mtx);
}
/**
@@ -614,6 +616,7 @@
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 @@
}
dev->power.status = DPM_OFF_IRQ;
}
+ mutex_unlock(&dpm_list_mtx);
if (error)
device_power_up(resume_event(state));
return error;
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 5a758c6e..e498377 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1451,7 +1451,6 @@
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 @@
enable_nonboot_cpus();
device_power_up(PMSG_RESTORE);
Resume_devices:
- device_pm_unlock();
device_resume(PMSG_RESTORE);
Resume_console:
resume_console();
diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index b0dc9e7..5cb080e 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -215,8 +215,6 @@
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 @@
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 @@
device_power_up(in_suspend ?
(error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
- Unlock:
- device_pm_unlock();
-
return error;
}
@@ -344,13 +339,11 @@
{
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 @@
device_power_up(PMSG_RECOVER);
- Unlock:
- device_pm_unlock();
-
return error;
}
@@ -464,11 +454,9 @@
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 @@
device_power_up(PMSG_RESTORE);
- Unlock:
- device_pm_unlock();
-
Resume_devices:
entering_platform_hibernation = false;
device_resume(PMSG_RESTORE);
diff --git a/kernel/power/main.c b/kernel/power/main.c
index f99ed6a..8680282 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -289,12 +289,10 @@
{
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 @@
if (suspend_ops->finish)
suspend_ops->finish();
- Done:
- device_pm_unlock();
-
return error;
}