[PATCH 4.14 23/71] ASoC: stm32: spdifrx: fix race condition in irq handler

Greg Kroah-Hartman
2020-01-16T23:36:20Z

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

commit 86e1956af4c863d653136fd6e5694adf2054dbaa upstream.

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

Fixes: 03e4d5d56fa5 ("ASoC: stm32: Add SPDIFRX support")

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Link: https://lore.kernel.org/r/20191204154333.7152-3-olivier.moysan@st.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/soc/stm/stm32_spdifrx.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)

--- a/sound/soc/stm/stm32_spdifrx.c
+++ b/sound/soc/stm/stm32_spdifrx.c
@@ -213,6 +213,7 @@
* @slave_config: dma slave channel runtime config pointer
* @phys_addr: SPDIFRX registers physical base address
* @lock: synchronization enabling lock
+ * @irq_lock: prevent race condition with IRQ on stream state
* @cs: channel status buffer
* @ub: user data buffer
* @irq: SPDIFRX interrupt line
@@ -233,6 +234,7 @@ struct stm32_spdifrx_data {
struct dma_slave_config slave_config;
dma_addr_t phys_addr;
spinlock_t lock; /* Sync enabling lock */
+ spinlock_t irq_lock; /* Prevent race condition on stream state */
unsigned char cs[SPDIFRX_CS_BYTES_NB];
unsigned char ub[SPDIFRX_UB_BYTES_NB];
int irq;
@@ -646,7 +648,6 @@ static const struct regmap_config stm32_
static irqreturn_t stm32_spdifrx_isr(int irq, void *devid)
{
struct stm32_spdifrx_data *spdifrx = (struct stm32_spdifrx_data *)devid;
- struct snd_pcm_substream *substream = spdifrx->substream;
struct platform_device *pdev = spdifrx->pdev;
unsigned int cr, mask, sr, imr;
unsigned int flags;
@@ -714,14 +715,19 @@ static irqreturn_t stm32_spdifrx_isr(int
regmap_update_bits(spdifrx->regmap, STM32_SPDIFRX_CR,
SPDIFRX_CR_SPDIFEN_MASK, cr);

- if (substream)
- snd_pcm_stop(substream, SNDRV_PCM_STATE_DISCONNECTED);
+ spin_lock(&spdifrx->irq_lock);
+ if (spdifrx->substream)
+ snd_pcm_stop(spdifrx->substream,
+ SNDRV_PCM_STATE_DISCONNECTED);
+ spin_unlock(&spdifrx->irq_lock);

return IRQ_HANDLED;
}

- if (err_xrun && substream)
- snd_pcm_stop_xrun(substream);
+ spin_lock(&spdifrx->irq_lock);
+ if (err_xrun && spdifrx->substream)
+ snd_pcm_stop_xrun(spdifrx->substream);
+ spin_unlock(&spdifrx->irq_lock);

return IRQ_HANDLED;
}
@@ -730,9 +736,12 @@ static int stm32_spdifrx_startup(struct
struct snd_soc_dai *cpu_dai)
{
struct stm32_spdifrx_data *spdifrx = snd_soc_dai_get_drvdata(cpu_dai);
+ unsigned long flags;
int ret;

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

ret = clk_prepare_enable(spdifrx->kclk);
if (ret)
@@ -804,8 +813,12 @@ static void stm32_spdifrx_shutdown(struc
struct snd_soc_dai *cpu_dai)
{
struct stm32_spdifrx_data *spdifrx = snd_soc_dai_get_drvdata(cpu_dai);
+ unsigned long flags;

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

@@ -910,6 +923,7 @@ static int stm32_spdifrx_probe(struct pl
spdifrx->pdev = pdev;
init_completion(&spdifrx->cs_completion);
spin_lock_init(&spdifrx->lock);
+ spin_lock_init(&spdifrx->irq_lock);

platform_set_drvdata(pdev, spdifrx);