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Commit 29338573 authored by Pierre-Louis Bossart's avatar Pierre-Louis Bossart Committed by Greg Kroah-Hartman
Browse files

ALSA: hda: hdac_ext_stream: fix potential locking issues 



commit 868ddfcef31ff93ea8961b2e81ea7fe12f6f144b upstream.

The code for hdac_ext_stream seems inherited from hdac_stream, and
similar locking issues are present: the use of the bus->reg_lock
spinlock is inconsistent, with only writes to specific fields being
protected.

Apply similar fix as in hdac_stream by protecting all accesses to
'link_locked' and 'decoupled' fields, with a new helper
snd_hdac_ext_stream_decouple_locked() added to simplify code
changes.

Signed-off-by: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210924192417.169243-4-pierre-louis.bossart@linux.intel.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 201340ca

include/sound/hdaudio_ext.h

+2 −0
Original line number Diff line number Diff line
@@ -88,6 +88,8 @@ struct hdac_ext_stream *snd_hdac_ext_stream_assign(struct hdac_bus *bus, 
					   struct snd_pcm_substream *substream,

					   int type);

void snd_hdac_ext_stream_release(struct hdac_ext_stream *azx_dev, int type);

void snd_hdac_ext_stream_decouple_locked(struct hdac_bus *bus,

				  struct hdac_ext_stream *azx_dev, bool decouple);

void snd_hdac_ext_stream_decouple(struct hdac_bus *bus,

				struct hdac_ext_stream *azx_dev, bool decouple);

void snd_hdac_ext_stop_streams(struct hdac_bus *bus);

sound/hda/ext/hdac_ext_stream.c

+28 −18
Original line number Diff line number Diff line
@@ -106,20 +106,14 @@ void snd_hdac_stream_free_all(struct hdac_bus *bus) 
}

EXPORT_SYMBOL_GPL(snd_hdac_stream_free_all);



/**

 * snd_hdac_ext_stream_decouple - decouple the hdac stream

 * @bus: HD-audio core bus

 * @stream: HD-audio ext core stream object to initialize

 * @decouple: flag to decouple

 */

void snd_hdac_ext_stream_decouple(struct hdac_bus *bus,

				struct hdac_ext_stream *stream, bool decouple)

void snd_hdac_ext_stream_decouple_locked(struct hdac_bus *bus,

					 struct hdac_ext_stream *stream,

					 bool decouple)

{

	struct hdac_stream *hstream = &stream->hstream;

	u32 val;

	int mask = AZX_PPCTL_PROCEN(hstream->index);



	spin_lock_irq(&bus->reg_lock);

	val = readw(bus->ppcap + AZX_REG_PP_PPCTL) & mask;



	if (decouple && !val)
@@ -128,6 +122,20 @@ void snd_hdac_ext_stream_decouple(struct hdac_bus *bus, 
		snd_hdac_updatel(bus->ppcap, AZX_REG_PP_PPCTL, mask, 0);



	stream->decoupled = decouple;

}

EXPORT_SYMBOL_GPL(snd_hdac_ext_stream_decouple_locked);



/**

 * snd_hdac_ext_stream_decouple - decouple the hdac stream

 * @bus: HD-audio core bus

 * @stream: HD-audio ext core stream object to initialize

 * @decouple: flag to decouple

 */

void snd_hdac_ext_stream_decouple(struct hdac_bus *bus,

				  struct hdac_ext_stream *stream, bool decouple)

{

	spin_lock_irq(&bus->reg_lock);

	snd_hdac_ext_stream_decouple_locked(bus, stream, decouple);

	spin_unlock_irq(&bus->reg_lock);

}

EXPORT_SYMBOL_GPL(snd_hdac_ext_stream_decouple);
@@ -252,6 +260,7 @@ hdac_ext_link_stream_assign(struct hdac_bus *bus, 
		return NULL;

	}



	spin_lock_irq(&bus->reg_lock);

	list_for_each_entry(stream, &bus->stream_list, list) {

		struct hdac_ext_stream *hstream = container_of(stream,

						struct hdac_ext_stream,
@@ -266,17 +275,16 @@ hdac_ext_link_stream_assign(struct hdac_bus *bus, 
		}



		if (!hstream->link_locked) {

			snd_hdac_ext_stream_decouple(bus, hstream, true);

			snd_hdac_ext_stream_decouple_locked(bus, hstream, true);

			res = hstream;

			break;

		}

	}

	if (res) {

		spin_lock_irq(&bus->reg_lock);

		res->link_locked = 1;

		res->link_substream = substream;

		spin_unlock_irq(&bus->reg_lock);

	}

	spin_unlock_irq(&bus->reg_lock);

	return res;

}
@@ -292,6 +300,7 @@ hdac_ext_host_stream_assign(struct hdac_bus *bus, 
		return NULL;

	}



	spin_lock_irq(&bus->reg_lock);

	list_for_each_entry(stream, &bus->stream_list, list) {

		struct hdac_ext_stream *hstream = container_of(stream,

						struct hdac_ext_stream,
@@ -301,18 +310,17 @@ hdac_ext_host_stream_assign(struct hdac_bus *bus, 


		if (!stream->opened) {

			if (!hstream->decoupled)

				snd_hdac_ext_stream_decouple(bus, hstream, true);

				snd_hdac_ext_stream_decouple_locked(bus, hstream, true);

			res = hstream;

			break;

		}

	}

	if (res) {

		spin_lock_irq(&bus->reg_lock);

		res->hstream.opened = 1;

		res->hstream.running = 0;

		res->hstream.substream = substream;

		spin_unlock_irq(&bus->reg_lock);

	}

	spin_unlock_irq(&bus->reg_lock);



	return res;

}
@@ -378,15 +386,17 @@ void snd_hdac_ext_stream_release(struct hdac_ext_stream *stream, int type) 
		break;



	case HDAC_EXT_STREAM_TYPE_HOST:

		spin_lock_irq(&bus->reg_lock);

		if (stream->decoupled && !stream->link_locked)

			snd_hdac_ext_stream_decouple(bus, stream, false);

			snd_hdac_ext_stream_decouple_locked(bus, stream, false);

		spin_unlock_irq(&bus->reg_lock);

		snd_hdac_stream_release(&stream->hstream);

		break;



	case HDAC_EXT_STREAM_TYPE_LINK:

		if (stream->decoupled && !stream->hstream.opened)

			snd_hdac_ext_stream_decouple(bus, stream, false);

		spin_lock_irq(&bus->reg_lock);

		if (stream->decoupled && !stream->hstream.opened)

			snd_hdac_ext_stream_decouple_locked(bus, stream, false);

		stream->link_locked = 0;

		stream->link_substream = NULL;

		spin_unlock_irq(&bus->reg_lock);