[PATCH AUTOSEL 5.0 06/79] ASoC: stm32: sai: fix race condition in irq handler

Sasha Levin
2019-04-27T01:56:48Z

From: Olivier Moysan <olivier.moysan@st.com>

[ Upstream commit 26f98e82dd49b7c3cc5ef0edd882aa732a62b672 ]

When snd_pcm_stop_xrun() is called in interrupt routine,
substream context may have already been released.
Add protection on substream context.

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/soc/stm/stm32_sai_sub.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/sound/soc/stm/stm32_sai_sub.c b/sound/soc/stm/stm32_sai_sub.c
index de4855b30e36..cc56102881be 100644
--- a/sound/soc/stm/stm32_sai_sub.c
+++ b/sound/soc/stm/stm32_sai_sub.c
@@ -102,6 +102,7 @@
* @spdif_frm_cnt: S/PDIF playback frame counter
* @iec958: iec958 data
* @ctrl_lock: control lock
+ * @irq_lock: prevent race condition with IRQ
*/
struct stm32_sai_sub_data {
struct platform_device *pdev;
@@ -133,6 +134,7 @@ struct stm32_sai_sub_data {
unsigned int spdif_frm_cnt;
struct snd_aes_iec958 iec958;
struct mutex ctrl_lock; /* protect resources accessed by controls */
+ spinlock_t irq_lock; /* used to prevent race condition with IRQ */
};

enum stm32_sai_fifo_th {
@@ -474,8 +476,10 @@ static irqreturn_t stm32_sai_isr(int irq, void *devid)
status = SNDRV_PCM_STATE_XRUN;
}

- if (status != SNDRV_PCM_STATE_RUNNING)
+ spin_lock(&sai->irq_lock);
+ if (status != SNDRV_PCM_STATE_RUNNING && sai->substream)
snd_pcm_stop_xrun(sai->substream);
+ spin_unlock(&sai->irq_lock);

return IRQ_HANDLED;
}
@@ -679,8 +683,11 @@ static int stm32_sai_startup(struct snd_pcm_substream *substream,
{
struct stm32_sai_sub_data *sai = snd_soc_dai_get_drvdata(cpu_dai);
int imr, cr2, ret;
+ unsigned long flags;

+ spin_lock_irqsave(&sai->irq_lock, flags);
sai->substream = substream;
+ spin_unlock_irqrestore(&sai->irq_lock, flags);

if (STM_SAI_PROTOCOL_IS_SPDIF(sai)) {
snd_pcm_hw_constraint_mask64(substream->runtime,
@@ -1061,6 +1068,7 @@ static void stm32_sai_shutdown(struct snd_pcm_substream *substream,
struct snd_soc_dai *cpu_dai)
{
struct stm32_sai_sub_data *sai = snd_soc_dai_get_drvdata(cpu_dai);
+ unsigned long flags;

regmap_update_bits(sai->regmap, STM_SAI_IMR_REGX, SAI_XIMR_MASK, 0);

@@ -1071,7 +1079,9 @@ static void stm32_sai_shutdown(struct snd_pcm_substream *substream,

clk_rate_exclusive_put(sai->sai_mclk);

+ spin_lock_irqsave(&sai->irq_lock, flags);
sai->substream = NULL;
+ spin_unlock_irqrestore(&sai->irq_lock, flags);
}

static int stm32_sai_pcm_new(struct snd_soc_pcm_runtime *rtd,
@@ -1435,6 +1445,7 @@ static int stm32_sai_sub_probe(struct platform_device *pdev)

sai->pdev = pdev;
mutex_init(&sai->ctrl_lock);
+ spin_lock_init(&sai->irq_lock);
platform_set_drvdata(pdev, sai);

sai->pdata = dev_get_drvdata(pdev->dev.parent);
--
2.19.1