ASoC: stm32: i2s: fix race condition in irq handler

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>

diff --git a/sound/soc/stm/stm32_i2s.c b/sound/soc/stm/stm32_i2s.c
index 9edb753..42ce87a 100644 (file)
--- a/sound/soc/stm/stm32_i2s.c
+++ b/sound/soc/stm/stm32_i2s.c
@@ -201,6 +201,7 @@ enum i2s_datlen {
  * @base:  mmio register base virtual address
  * @phys_addr: I2S registers physical base address
  * @lock_fd: lock to manage race conditions in full duplex mode
+ * @irq_lock: prevent race condition with IRQ
  * @dais_name: DAI name
  * @mclk_rate: master clock frequency (Hz)
  * @fmt: DAI protocol
@@ -222,6 +223,7 @@ struct stm32_i2s_data {
        void __iomem *base;
        dma_addr_t phys_addr;
        spinlock_t lock_fd; /* Manage race conditions for full duplex */
+       spinlock_t irq_lock; /* used to prevent race condition with IRQ */
        char dais_name[STM32_I2S_DAI_NAME_SIZE];
        unsigned int mclk_rate;
        unsigned int fmt;
@@ -263,8 +265,10 @@ static irqreturn_t stm32_i2s_isr(int irq, void *devid)
        if (flags & I2S_SR_TIFRE)
                dev_dbg(&pdev->dev, "Frame error\n");
 
-       if (err)
+       spin_lock(&i2s->irq_lock);
+       if (err && i2s->substream)
                snd_pcm_stop_xrun(i2s->substream);
+       spin_unlock(&i2s->irq_lock);
 
        return IRQ_HANDLED;
 }
@@ -540,9 +544,12 @@ static int stm32_i2s_startup(struct snd_pcm_substream *substream,
                             struct snd_soc_dai *cpu_dai)
 {
        struct stm32_i2s_data *i2s = snd_soc_dai_get_drvdata(cpu_dai);
+       unsigned long flags;
        int ret;
 
+       spin_lock_irqsave(&i2s->irq_lock, flags);
        i2s->substream = substream;
+       spin_unlock_irqrestore(&i2s->irq_lock, flags);
 
        ret = clk_prepare_enable(i2s->i2sclk);
        if (ret < 0) {
@@ -673,13 +680,16 @@ static void stm32_i2s_shutdown(struct snd_pcm_substream *substream,
                               struct snd_soc_dai *cpu_dai)
 {
        struct stm32_i2s_data *i2s = snd_soc_dai_get_drvdata(cpu_dai);
-
-       i2s->substream = NULL;
+       unsigned long flags;
 
        regmap_update_bits(i2s->regmap, STM32_I2S_CGFR_REG,
                           I2S_CGFR_MCKOE, (unsigned int)~I2S_CGFR_MCKOE);
 
        clk_disable_unprepare(i2s->i2sclk);
+
+       spin_lock_irqsave(&i2s->irq_lock, flags);
+       i2s->substream = NULL;
+       spin_unlock_irqrestore(&i2s->irq_lock, flags);
 }
 
 static int stm32_i2s_dai_probe(struct snd_soc_dai *cpu_dai)
@@ -874,6 +884,7 @@ static int stm32_i2s_probe(struct platform_device *pdev)
        i2s->pdev = pdev;
        i2s->ms_flg = I2S_MS_NOT_SET;
        spin_lock_init(&i2s->lock_fd);
+       spin_lock_init(&i2s->irq_lock);
        platform_set_drvdata(pdev, i2s);
 
        ret = stm32_i2s_dais_init(pdev, i2s);