On Mon, 20 Mar 2017 18:09:15 +0100, Arnaud Pouliquen wrote:
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 call snd_pcm_stream_lock is player->substream is already null.
Hrm, how the first call of snd_pcm_stream_lock() with player->substream to be guaranteed to be non-NULL?
Takashi
Signed-off-by: Arnaud Pouliquen arnaud.pouliquen@st.com
sound/soc/sti/uniperif_player.c | 9 +++------ sound/soc/sti/uniperif_reader.c | 8 +++++--- 2 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/sound/soc/sti/uniperif_player.c b/sound/soc/sti/uniperif_player.c index 60ae31a..6fa9eee 100644 --- a/sound/soc/sti/uniperif_player.c +++ b/sound/soc/sti/uniperif_player.c @@ -65,8 +65,10 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id) unsigned int status; unsigned int tmp;
- snd_pcm_stream_lock(player->substream); if (player->state == UNIPERIF_STATE_STOPPED) { /* Unexpected IRQ: do nothing */
snd_pcm_stream_unlock(player->substream);@@ -88,9 +90,7 @@ 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 +104,7 @@ 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; }
@@ -138,13 +136,12 @@ 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; }
- snd_pcm_stream_unlock(player->substream); return ret;
}
diff --git a/sound/soc/sti/uniperif_reader.c b/sound/soc/sti/uniperif_reader.c index 5992c6a..9273f59 100644 --- a/sound/soc/sti/uniperif_reader.c +++ b/sound/soc/sti/uniperif_reader.c @@ -46,9 +46,11 @@ static irqreturn_t uni_reader_irq_handler(int irq, void *dev_id) struct uniperif *reader = dev_id; unsigned int status;
- snd_pcm_stream_lock(reader->substream); if (reader->state == UNIPERIF_STATE_STOPPED) { /* Unexpected IRQ: do nothing */ dev_warn(reader->dev, "unexpected IRQ\n");
snd_pcm_stream_unlock(reader->substream);@@ -60,13 +62,13 @@ 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;}
snd_pcm_stream_unlock(reader->substream);
return ret;
}
-- 1.9.1