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authorRafael J. Wysocki <rjw@sisk.pl>2009-05-24 21:15:07 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2009-05-24 21:15:07 +0200
commit32bdfac5462d777f35b00838893c4f87baf23efe (patch)
tree92e4ef3af7b68007e8004eaca978865a29e543b0 /drivers/base/power/main.c
parent59a3759d0fe8d969888c741bb33f4946e4d3750d (diff)
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>
Diffstat (limited to 'drivers/base/power/main.c')
-rw-r--r--drivers/base/power/main.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 69b4ddb7de3..3e4bc699bc0 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -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;