2022-01-10 09:48:50

by Prabhakar Mahadev Lad

[permalink] [raw]
Subject: [PATCH 5/5] ASoC: sh: rz-ssi: Add functions to get/set substream pointer

A copy of substream pointer is stored in priv structure during
rz_ssi_dai_trigger() callback ie in SNDRV_PCM_TRIGGER_START case
and the pointer is assigned to NULL in case of SNDRV_PCM_TRIGGER_STOP.

The driver used the locks only in rz_ssi_stream_is_valid() and assigned
the local substream pointer to NULL in rz_ssi_dai_trigger() callback and
in rest of the driver no locking was used while assigning substream
pointer.

This patch adds functions to get/set substream pointer with locks acquired
and replaces the instances of access to substream pointer with the
get/set functions.

Reported-by: Pavel Machek <[email protected]>
Signed-off-by: Lad Prabhakar <[email protected]>
Reviewed-by: Biju Das <[email protected]>
---
sound/soc/sh/rz-ssi.c | 55 ++++++++++++++++++++++++++++++++-----------
1 file changed, 41 insertions(+), 14 deletions(-)

diff --git a/sound/soc/sh/rz-ssi.c b/sound/soc/sh/rz-ssi.c
index aabd15e9d515..057aedacedec 100644
--- a/sound/soc/sh/rz-ssi.c
+++ b/sound/soc/sh/rz-ssi.c
@@ -201,12 +201,36 @@ static bool rz_ssi_stream_is_valid(struct rz_ssi_priv *ssi,
return ret;
}

+static struct snd_pcm_substream *rz_ssi_get_substream(struct rz_ssi_stream *strm)
+{
+ struct rz_ssi_priv *ssi = strm->priv;
+ struct snd_pcm_substream *substream;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ssi->lock, flags);
+ substream = strm->substream;
+ spin_unlock_irqrestore(&ssi->lock, flags);
+
+ return substream;
+}
+
+static void rz_ssi_set_substream(struct rz_ssi_stream *strm,
+ struct snd_pcm_substream *substream)
+{
+ struct rz_ssi_priv *ssi = strm->priv;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ssi->lock, flags);
+ strm->substream = substream;
+ spin_unlock_irqrestore(&ssi->lock, flags);
+}
+
static void rz_ssi_stream_init(struct rz_ssi_stream *strm,
struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;

- strm->substream = substream;
+ rz_ssi_set_substream(strm, substream);
strm->sample_width = samples_to_bytes(runtime, 1);
strm->dma_buffer_pos = 0;
strm->period_counter = 0;
@@ -223,12 +247,13 @@ static void rz_ssi_stream_init(struct rz_ssi_stream *strm,
static void rz_ssi_stream_quit(struct rz_ssi_priv *ssi,
struct rz_ssi_stream *strm)
{
- struct snd_soc_dai *dai = rz_ssi_get_dai(strm->substream);
- unsigned long flags;
+ struct snd_pcm_substream *substream;
+ struct snd_soc_dai *dai;

- spin_lock_irqsave(&ssi->lock, flags);
- strm->substream = NULL;
- spin_unlock_irqrestore(&ssi->lock, flags);
+ substream = rz_ssi_get_substream(strm);
+ rz_ssi_set_substream(strm, NULL);
+
+ dai = rz_ssi_get_dai(substream);

if (strm->oerr_num > 0)
dev_info(dai->dev, "overrun = %d\n", strm->oerr_num);
@@ -301,7 +326,8 @@ static int rz_ssi_clk_setup(struct rz_ssi_priv *ssi, unsigned int rate,

static int rz_ssi_start(struct rz_ssi_priv *ssi, struct rz_ssi_stream *strm)
{
- bool is_play = rz_ssi_stream_is_play(ssi, strm->substream);
+ struct snd_pcm_substream *substream = rz_ssi_get_substream(strm);
+ bool is_play = rz_ssi_stream_is_play(ssi, substream);
u32 ssicr, ssifcr;

ssicr = rz_ssi_reg_readl(ssi, SSICR);
@@ -382,7 +408,7 @@ static int rz_ssi_stop(struct rz_ssi_priv *ssi, struct rz_ssi_stream *strm)

static void rz_ssi_pointer_update(struct rz_ssi_stream *strm, int frames)
{
- struct snd_pcm_substream *substream = strm->substream;
+ struct snd_pcm_substream *substream = rz_ssi_get_substream(strm);
struct snd_pcm_runtime *runtime;
int current_period;

@@ -399,14 +425,14 @@ static void rz_ssi_pointer_update(struct rz_ssi_stream *strm, int frames)

current_period = strm->buffer_pos / runtime->period_size;
if (strm->period_counter != current_period) {
- snd_pcm_period_elapsed(strm->substream);
+ snd_pcm_period_elapsed(substream);
strm->period_counter = current_period;
}
}

static int rz_ssi_pio_recv(struct rz_ssi_priv *ssi, struct rz_ssi_stream *strm)
{
- struct snd_pcm_substream *substream = strm->substream;
+ struct snd_pcm_substream *substream = rz_ssi_get_substream(strm);
struct snd_pcm_runtime *runtime;
bool done = false;
u16 *buf;
@@ -464,7 +490,7 @@ static int rz_ssi_pio_recv(struct rz_ssi_priv *ssi, struct rz_ssi_stream *strm)

static int rz_ssi_pio_send(struct rz_ssi_priv *ssi, struct rz_ssi_stream *strm)
{
- struct snd_pcm_substream *substream = strm->substream;
+ struct snd_pcm_substream *substream = rz_ssi_get_substream(strm);
struct snd_pcm_runtime *runtime = substream->runtime;
int sample_space;
int samples = 0;
@@ -588,7 +614,7 @@ static int rz_ssi_dma_slave_config(struct rz_ssi_priv *ssi,
static int rz_ssi_dma_transfer(struct rz_ssi_priv *ssi,
struct rz_ssi_stream *strm)
{
- struct snd_pcm_substream *substream = strm->substream;
+ struct snd_pcm_substream *substream = rz_ssi_get_substream(strm);
struct dma_async_tx_descriptor *desc;
struct snd_pcm_runtime *runtime;
enum dma_transfer_direction dir;
@@ -646,12 +672,13 @@ static int rz_ssi_dma_transfer(struct rz_ssi_priv *ssi,
static void rz_ssi_dma_complete(void *data)
{
struct rz_ssi_stream *strm = (struct rz_ssi_stream *)data;
+ struct snd_pcm_substream *substream = rz_ssi_get_substream(strm);

- if (!strm->running || !strm->substream || !strm->substream->runtime)
+ if (!strm->running || !substream || !substream->runtime)
return;

/* Note that next DMA transaction has probably already started */
- rz_ssi_pointer_update(strm, strm->substream->runtime->period_size);
+ rz_ssi_pointer_update(strm, substream->runtime->period_size);

/* Queue up another DMA transaction */
rz_ssi_dma_transfer(strm->priv, strm);
--
2.17.1



2022-01-10 15:10:28

by Mark Brown

[permalink] [raw]
Subject: Re: [PATCH 5/5] ASoC: sh: rz-ssi: Add functions to get/set substream pointer

On Mon, Jan 10, 2022 at 09:47:11AM +0000, Lad Prabhakar wrote:

> +static struct snd_pcm_substream *rz_ssi_get_substream(struct rz_ssi_stream *strm)
> +{
> + struct rz_ssi_priv *ssi = strm->priv;
> + struct snd_pcm_substream *substream;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&ssi->lock, flags);
> + substream = strm->substream;
> + spin_unlock_irqrestore(&ssi->lock, flags);

This locking doesn't seem useful, we just take a copy of the lock and
then immediately return so the lock isn't protecting anything in
particular - the caller can happily continue using the substream after
the variable has been updated.


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2022-01-10 16:14:50

by Lad, Prabhakar

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Subject: Re: [PATCH 5/5] ASoC: sh: rz-ssi: Add functions to get/set substream pointer

Hi Mark,

Thank you for the review.

On Mon, Jan 10, 2022 at 3:10 PM Mark Brown <[email protected]> wrote:
>
> On Mon, Jan 10, 2022 at 09:47:11AM +0000, Lad Prabhakar wrote:
>
> > +static struct snd_pcm_substream *rz_ssi_get_substream(struct rz_ssi_stream *strm)
> > +{
> > + struct rz_ssi_priv *ssi = strm->priv;
> > + struct snd_pcm_substream *substream;
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&ssi->lock, flags);
> > + substream = strm->substream;
> > + spin_unlock_irqrestore(&ssi->lock, flags);
>
> This locking doesn't seem useful, we just take a copy of the lock and
> then immediately return so the lock isn't protecting anything in
> particular - the caller can happily continue using the substream after
> the variable has been updated.
>
Ok will drop the locking from get function.

Cheers,
Prabhakar