[PATCH 4.4 19/50] ASoC: samsung: Use IRQ safe spin lock calls

Greg Kroah-Hartman
2016-03-14T18:20:22Z

From: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>

commit 316fa9e09ad76e095b9d7e9350c628b918370a22 upstream.

Lockdep warns of a potential lock inversion, i2s->lock is held numerous
times whilst we are under the substream lock (snd_pcm_stream_lock). If
we use the IRQ unsafe spin lock calls, you can also end up locking
snd_pcm_stream_lock whilst under i2s->lock (if an IRQ happens whilst we
are holding i2s->lock). This could result in deadlock.

[ 18.147001] CPU0 CPU1
[ 18.151509] ---- ----
[ 18.156022] lock(&(&pri_dai->spinlock)->rlock);
[ 18.160701] local_irq_disable();
[ 18.166622] lock(&(&substream->self_group.lock)->rlock);
[ 18.174595] lock(&(&pri_dai->spinlock)->rlock);
[ 18.181806] <Interrupt>
[ 18.184408] lock(&(&substream->self_group.lock)->rlock);
[ 18.190045]
[ 18.190045] *** DEADLOCK ***

This patch changes to using the irq safe spinlock calls, to avoid this
issue.

Fixes: ce8bcdbb61d9 ("ASoC: samsung: i2s: Protect more registers with a spinlock")
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Tested-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/soc/samsung/i2s.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)

--- a/sound/soc/samsung/i2s.c
+++ b/sound/soc/samsung/i2s.c
@@ -480,10 +480,11 @@ static int i2s_set_sysclk(struct snd_soc
unsigned int cdcon_mask = 1 << i2s_regs->cdclkcon_off;
unsigned int rsrc_mask = 1 << i2s_regs->rclksrc_off;
u32 mod, mask, val = 0;
+ unsigned long flags;

- spin_lock(i2s->lock);
+ spin_lock_irqsave(i2s->lock, flags);
mod = readl(i2s->addr + I2SMOD);
- spin_unlock(i2s->lock);
+ spin_unlock_irqrestore(i2s->lock, flags);

switch (clk_id) {
case SAMSUNG_I2S_OPCLK:
@@ -574,11 +575,11 @@ static int i2s_set_sysclk(struct snd_soc
return -EINVAL;
}

- spin_lock(i2s->lock);
+ spin_lock_irqsave(i2s->lock, flags);
mod = readl(i2s->addr + I2SMOD);
mod = (mod & ~mask) | val;
writel(mod, i2s->addr + I2SMOD);
- spin_unlock(i2s->lock);
+ spin_unlock_irqrestore(i2s->lock, flags);

return 0;
}
@@ -589,6 +590,7 @@ static int i2s_set_fmt(struct snd_soc_da
struct i2s_dai *i2s = to_info(dai);
int lrp_shift, sdf_shift, sdf_mask, lrp_rlow, mod_slave;
u32 mod, tmp = 0;
+ unsigned long flags;

lrp_shift = i2s->variant_regs->lrp_off;
sdf_shift = i2s->variant_regs->sdf_off;
@@ -648,7 +650,7 @@ static int i2s_set_fmt(struct snd_soc_da
return -EINVAL;
}

- spin_lock(i2s->lock);
+ spin_lock_irqsave(i2s->lock, flags);
mod = readl(i2s->addr + I2SMOD);
/*
* Don't change the I2S mode if any controller is active on this
@@ -656,7 +658,7 @@ static int i2s_set_fmt(struct snd_soc_da
*/
if (any_active(i2s) &&
((mod & (sdf_mask | lrp_rlow | mod_slave)) != tmp)) {
- spin_unlock(i2s->lock);
+ spin_unlock_irqrestore(i2s->lock, flags);
dev_err(&i2s->pdev->dev,
"%s:%d Other DAI busy\n", __func__, __LINE__);
return -EAGAIN;
@@ -665,7 +667,7 @@ static int i2s_set_fmt(struct snd_soc_da
mod &= ~(sdf_mask | lrp_rlow | mod_slave);
mod |= tmp;
writel(mod, i2s->addr + I2SMOD);
- spin_unlock(i2s->lock);
+ spin_unlock_irqrestore(i2s->lock, flags);

return 0;
}
@@ -675,6 +677,7 @@ static int i2s_hw_params(struct snd_pcm_
{
struct i2s_dai *i2s = to_info(dai);
u32 mod, mask = 0, val = 0;
+ unsigned long flags;

if (!is_secondary(i2s))
mask |= (MOD_DC2_EN | MOD_DC1_EN);
@@ -743,11 +746,11 @@ static int i2s_hw_params(struct snd_pcm_
return -EINVAL;
}

- spin_lock(i2s->lock);
+ spin_lock_irqsave(i2s->lock, flags);
mod = readl(i2s->addr + I2SMOD);
mod = (mod & ~mask) | val;
writel(mod, i2s->addr + I2SMOD);
- spin_unlock(i2s->lock);
+ spin_unlock_irqrestore(i2s->lock, flags);

samsung_asoc_init_dma_data(dai, &i2s->dma_playback, &i2s->dma_capture);