On Tue, Nov 7, 2017 at 11:47 PM, Rafael J. Wysocki rafael@kernel.org wrote:
On Tue, Nov 7, 2017 at 10:08 PM, Ville Syrjala ville.syrjala@linux.intel.com wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
acpi_remove_pm_notifier() ends up calling flush_workqueue() while holding acpi_pm_notifier_lock, and that same lock is taken by by the work via acpi_pm_notify_handler(). This can deadlock.
OK, good catch!
[cut]
Cc: stable@vger.kernel.org Cc: Rafael J. Wysocki rafael.j.wysocki@intel.com Cc: Len Brown lenb@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Tejun Heo tj@kernel.org Cc: Ingo Molnar mingo@kernel.org Fixes: c072530f391e ("ACPI / PM: Revork the handling of ACPI device wakeup notifications") Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
drivers/acpi/device_pm.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-)
diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c index fbcc73f7a099..18af71057b44 100644 --- a/drivers/acpi/device_pm.c +++ b/drivers/acpi/device_pm.c @@ -387,6 +387,7 @@ EXPORT_SYMBOL(acpi_bus_power_manageable);
#ifdef CONFIG_PM static DEFINE_MUTEX(acpi_pm_notifier_lock); +static DEFINE_MUTEX(acpi_pm_notifier_install_lock);
void acpi_pm_wakeup_event(struct device *dev) { @@ -443,24 +444,25 @@ acpi_status acpi_add_pm_notifier(struct acpi_device *adev, struct device *dev, if (!dev && !func) return AE_BAD_PARAMETER;
mutex_lock(&acpi_pm_notifier_lock);
mutex_lock(&acpi_pm_notifier_install_lock); if (adev->wakeup.flags.notifier_present) goto out;
adev->wakeup.ws = wakeup_source_register(dev_name(&adev->dev));adev->wakeup.context.dev = dev;adev->wakeup.context.func = func;But this doesn't look good to me.
notifier_present should be checked under acpi_pm_notifier_lock.
Well, not really, so the above is OK.
However, I still would prefer to avoid adding the outer lock.
Thanks, Rafael