ALSA: hda: hdac_ext_stream: fix potential locking issues

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: Pierre-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: Takashi Iwai <tiwai@suse.de>

diff --git a/include/sound/hdaudio_ext.h b/include/sound/hdaudio_ext.h
index 3755816..d4e31ea 100644 (file)
--- a/include/sound/hdaudio_ext.h
+++ b/include/sound/hdaudio_ext.h
@@ -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);

diff --git a/sound/hda/ext/hdac_ext_stream.c b/sound/hda/ext/hdac_ext_stream.c
index 0c005d6..37154ed 100644 (file)
--- a/sound/hda/ext/hdac_ext_stream.c
+++ b/sound/hda/ext/hdac_ext_stream.c
@@ -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);