With RTlinux a race condition has been found that leads to NULL ptr crash: - On CPU 0: uni_player_irq_handler is called to treat XRUN "(player->state == UNIPERIF_STATE_STOPPED)" is FALSE so status is checked, dev_err(player->dev, "FIFO underflow error detected") is printed and then snd_pcm_stream_lock should be called to lock stream for stopping. - On CPU 1: application stop and close the stream. Issue is that the stop and shutdown functions are executed while "FIFO underflow error detected" is printed. So when CPU 0 calls snd_pcm_stream_lock, player->substream is already null.
Signed-off-by: Arnaud Pouliquen arnaud.pouliquen@st.com
--- V3: - Lower case for labels, - Fix lock-unlock balance.
V2: Add spinlock to protect player/reader->substream --- sound/soc/sti/uniperif.h | 1 + sound/soc/sti/uniperif_player.c | 35 ++++++++++++++++++++++++----------- sound/soc/sti/uniperif_reader.c | 24 ++++++++++++++++++++---- 3 files changed, 45 insertions(+), 15 deletions(-)
diff --git a/sound/soc/sti/uniperif.h b/sound/soc/sti/uniperif.h index d487dd2..cfcb0ea 100644 --- a/sound/soc/sti/uniperif.h +++ b/sound/soc/sti/uniperif.h @@ -1299,6 +1299,7 @@ struct uniperif { int ver; /* IP version, used by register access macros */ struct regmap_field *clk_sel; struct regmap_field *valid_sel; + spinlock_t irq_lock; /* use to prevent race condition with IRQ */
/* capabilities */ const struct snd_pcm_hardware *hw; diff --git a/sound/soc/sti/uniperif_player.c b/sound/soc/sti/uniperif_player.c index 60ae31a..d7e8dd4 100644 --- a/sound/soc/sti/uniperif_player.c +++ b/sound/soc/sti/uniperif_player.c @@ -65,10 +65,13 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id) unsigned int status; unsigned int tmp;
- if (player->state == UNIPERIF_STATE_STOPPED) { - /* Unexpected IRQ: do nothing */ - return IRQ_NONE; - } + spin_lock(&player->irq_lock); + if (!player->substream) + goto irq_spin_unlock; + + snd_pcm_stream_lock(player->substream); + if (player->state == UNIPERIF_STATE_STOPPED) + goto stream_unlock;
/* Get interrupt status & clear them immediately */ status = GET_UNIPERIF_ITS(player); @@ -88,9 +91,7 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id) SET_UNIPERIF_ITM_BCLR_FIFO_ERROR(player);
/* Stop the player */ - snd_pcm_stream_lock(player->substream); snd_pcm_stop(player->substream, SNDRV_PCM_STATE_XRUN); - snd_pcm_stream_unlock(player->substream); }
ret = IRQ_HANDLED; @@ -104,9 +105,7 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id) SET_UNIPERIF_ITM_BCLR_DMA_ERROR(player);
/* Stop the player */ - snd_pcm_stream_lock(player->substream); snd_pcm_stop(player->substream, SNDRV_PCM_STATE_XRUN); - snd_pcm_stream_unlock(player->substream);
ret = IRQ_HANDLED; } @@ -116,7 +115,8 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id) if (!player->underflow_enabled) { dev_err(player->dev, "unexpected Underflow recovering\n"); - return -EPERM; + ret = -EPERM; + goto stream_unlock; } /* Read the underflow recovery duration */ tmp = GET_UNIPERIF_STATUS_1_UNDERFLOW_DURATION(player); @@ -138,13 +138,16 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id) dev_err(player->dev, "Underflow recovery failed\n");
/* Stop the player */ - snd_pcm_stream_lock(player->substream); snd_pcm_stop(player->substream, SNDRV_PCM_STATE_XRUN); - snd_pcm_stream_unlock(player->substream);
ret = IRQ_HANDLED; }
+stream_unlock: + snd_pcm_stream_unlock(player->substream); +irq_spin_unlock: + spin_unlock(&player->irq_lock); + return ret; }
@@ -588,6 +591,7 @@ static int uni_player_ctl_iec958_put(struct snd_kcontrol *kcontrol, struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai); struct uniperif *player = priv->dai_data.uni; struct snd_aes_iec958 *iec958 = &player->stream_settings.iec958; + unsigned long flags;
mutex_lock(&player->ctrl_lock); iec958->status[0] = ucontrol->value.iec958.status[0]; @@ -596,12 +600,14 @@ static int uni_player_ctl_iec958_put(struct snd_kcontrol *kcontrol, iec958->status[3] = ucontrol->value.iec958.status[3]; mutex_unlock(&player->ctrl_lock);
+ spin_lock_irqsave(&player->irq_lock, flags); if (player->substream && player->substream->runtime) uni_player_set_channel_status(player, player->substream->runtime); else uni_player_set_channel_status(player, NULL);
+ spin_unlock_irqrestore(&player->irq_lock, flags); return 0; }
@@ -686,9 +692,12 @@ static int uni_player_startup(struct snd_pcm_substream *substream, { struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai); struct uniperif *player = priv->dai_data.uni; + unsigned long flags; int ret;
+ spin_lock_irqsave(&player->irq_lock, flags); player->substream = substream; + spin_unlock_irqrestore(&player->irq_lock, flags);
player->clk_adj = 0;
@@ -986,12 +995,15 @@ static void uni_player_shutdown(struct snd_pcm_substream *substream, { struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai); struct uniperif *player = priv->dai_data.uni; + unsigned long flags;
+ spin_lock_irqsave(&player->irq_lock, flags); if (player->state != UNIPERIF_STATE_STOPPED) /* Stop the player */ uni_player_stop(player);
player->substream = NULL; + spin_unlock_irqrestore(&player->irq_lock, flags); }
static int uni_player_parse_dt_audio_glue(struct platform_device *pdev, @@ -1096,6 +1108,7 @@ int uni_player_init(struct platform_device *pdev, }
mutex_init(&player->ctrl_lock); + spin_lock_init(&player->irq_lock);
/* Ensure that disabled by default */ SET_UNIPERIF_CONFIG_BACK_STALL_REQ_DISABLE(player); diff --git a/sound/soc/sti/uniperif_reader.c b/sound/soc/sti/uniperif_reader.c index 93a8df6..ee0055e 100644 --- a/sound/soc/sti/uniperif_reader.c +++ b/sound/soc/sti/uniperif_reader.c @@ -46,10 +46,15 @@ static irqreturn_t uni_reader_irq_handler(int irq, void *dev_id) struct uniperif *reader = dev_id; unsigned int status;
+ spin_lock(&reader->irq_lock); + if (!reader->substream) + goto irq_spin_unlock; + + snd_pcm_stream_lock(reader->substream); if (reader->state == UNIPERIF_STATE_STOPPED) { /* Unexpected IRQ: do nothing */ dev_warn(reader->dev, "unexpected IRQ\n"); - return IRQ_HANDLED; + goto stream_unlock; }
/* Get interrupt status & clear them immediately */ @@ -60,13 +65,16 @@ static irqreturn_t uni_reader_irq_handler(int irq, void *dev_id) if (unlikely(status & UNIPERIF_ITS_FIFO_ERROR_MASK(reader))) { dev_err(reader->dev, "FIFO error detected\n");
- snd_pcm_stream_lock(reader->substream); snd_pcm_stop(reader->substream, SNDRV_PCM_STATE_XRUN); - snd_pcm_stream_unlock(reader->substream);
- return IRQ_HANDLED; + ret = IRQ_HANDLED; }
+stream_unlock: + snd_pcm_stream_unlock(reader->substream); +irq_spin_unlock: + spin_unlock(&reader->irq_lock); + return ret; }
@@ -347,9 +355,12 @@ static int uni_reader_startup(struct snd_pcm_substream *substream, { struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai); struct uniperif *reader = priv->dai_data.uni; + unsigned long flags; int ret;
+ spin_lock_irqsave(&reader->irq_lock, flags); reader->substream = substream; + spin_unlock_irqrestore(&reader->irq_lock, flags);
if (!UNIPERIF_TYPE_IS_TDM(reader)) return 0; @@ -375,12 +386,15 @@ static void uni_reader_shutdown(struct snd_pcm_substream *substream, { struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai); struct uniperif *reader = priv->dai_data.uni; + unsigned long flags;
+ spin_lock_irqsave(&reader->irq_lock, flags); if (reader->state != UNIPERIF_STATE_STOPPED) { /* Stop the reader */ uni_reader_stop(reader); } reader->substream = NULL; + spin_unlock_irqrestore(&reader->irq_lock, flags); }
static const struct snd_soc_dai_ops uni_reader_dai_ops = { @@ -415,6 +429,8 @@ int uni_reader_init(struct platform_device *pdev, return -EBUSY; }
+ spin_lock_init(&reader->irq_lock); + return 0; } EXPORT_SYMBOL_GPL(uni_reader_init);