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Commit d7a181da authored by Takashi Iwai's avatar Takashi Iwai
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ALSA: hda: Fix racy display power access 



snd_hdac_display_power() doesn't handle the concurrent calls carefully
enough, and it may lead to the doubly get_power or put_power calls,
when a runtime PM and an async work get called in racy way.

This patch addresses it by reusing the bus->lock mutex that has been
used for protecting the link state change in ext bus code, so that it
can protect against racy display state changes.  The initialization of
bus->lock was moved from snd_hdac_ext_bus_init() to
snd_hdac_bus_init() as well accordingly.

Testcase: igt/i915_pm_rpm/module-reload #glk-dsi
Reported-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent cae30527

sound/hda/ext/hdac_ext_bus.c

+0 −1
Original line number Diff line number Diff line
@@ -107,7 +107,6 @@ int snd_hdac_ext_bus_init(struct hdac_bus *bus, struct device *dev, 
	INIT_LIST_HEAD(&bus->hlink_list);

	bus->idx = idx++;



	mutex_init(&bus->lock);

	bus->cmd_dma_state = true;



	return 0;

sound/hda/hdac_bus.c

+1 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ int snd_hdac_bus_init(struct hdac_bus *bus, struct device *dev, 
	INIT_WORK(&bus->unsol_work, snd_hdac_bus_process_unsol_events);

	spin_lock_init(&bus->reg_lock);

	mutex_init(&bus->cmd_mutex);

	mutex_init(&bus->lock);

	bus->irq = -1;

	return 0;

}

sound/hda/hdac_component.c

+5 −1
Original line number Diff line number Diff line
@@ -69,13 +69,15 @@ void snd_hdac_display_power(struct hdac_bus *bus, unsigned int idx, bool enable) 


	dev_dbg(bus->dev, "display power %s\n",

		enable ? "enable" : "disable");



	mutex_lock(&bus->lock);

	if (enable)

		set_bit(idx, &bus->display_power_status);

	else

		clear_bit(idx, &bus->display_power_status);



	if (!acomp || !acomp->ops)

		return;

		goto unlock;



	if (bus->display_power_status) {

		if (!bus->display_power_active) {
@@ -92,6 +94,8 @@ void snd_hdac_display_power(struct hdac_bus *bus, unsigned int idx, bool enable) 
			bus->display_power_active = false;

		}

	}

 unlock:

	mutex_unlock(&bus->lock);

}

EXPORT_SYMBOL_GPL(snd_hdac_display_power);