2023-12-05 11:12:21

by Marcus Folkesson

Subject: [PATCH v3] iio: adc: mcp3911: simplify code with guard macro

Use the guard(mutex) macro for handle mutex lock/unlocks.

Signed-off-by: Marcus Folkesson <[email protected]>
---
Changes in v3:
- Return early in good paths as well
- Rebase against master
- Link to v2: https://lore.kernel.org/r/[email protected]

Changes in v2:
- Return directly instead of goto label
- Link to v1: https://lore.kernel.org/r/[email protected]
---
drivers/iio/adc/mcp3911.c | 47 +++++++++++++++--------------------------------
1 file changed, 15 insertions(+), 32 deletions(-)

diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index d864558bc087..f4822ecece89 100644
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -7,6 +7,7 @@
*/
#include <linux/bitfield.h>
#include <linux/bits.h>
+#include <linux/cleanup.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
@@ -318,44 +319,34 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
struct mcp3911 *adc = iio_priv(indio_dev);
int ret = -EINVAL;

- mutex_lock(&adc->lock);
+ guard(mutex)(&adc->lock);
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = mcp3911_read(adc,
MCP3911_CHANNEL(channel->channel), val, 3);
if (ret)
- goto out;
+ return ret;

*val = sign_extend32(*val, 23);
-
- ret = IIO_VAL_INT;
+ return IIO_VAL_INT;
break;

case IIO_CHAN_INFO_OFFSET:
-
ret = adc->chip->get_offset(adc, channel->channel, val);
- if (ret)
- goto out;
-
- ret = IIO_VAL_INT;
+ return (ret) ? ret : IIO_VAL_INT;
break;
case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
ret = adc->chip->get_osr(adc, val);
- if (ret)
- goto out;
-
- ret = IIO_VAL_INT;
+ return (ret) ? ret : IIO_VAL_INT;
break;

case IIO_CHAN_INFO_SCALE:
*val = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][0];
*val2 = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][1];
- ret = IIO_VAL_INT_PLUS_NANO;
+ return IIO_VAL_INT_PLUS_NANO;
break;
}

-out:
- mutex_unlock(&adc->lock);
return ret;
}

@@ -364,9 +355,8 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
int val2, long mask)
{
struct mcp3911 *adc = iio_priv(indio_dev);
- int ret = -EINVAL;

- mutex_lock(&adc->lock);
+ guard(mutex)(&adc->lock);
switch (mask) {
case IIO_CHAN_INFO_SCALE:
for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
@@ -374,32 +364,26 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
val2 == mcp3911_scale_table[i][1]) {

adc->gain[channel->channel] = BIT(i);
- ret = adc->chip->set_scale(adc, channel->channel, i);
+ return adc->chip->set_scale(adc, channel->channel, i);
}
}
break;
case IIO_CHAN_INFO_OFFSET:
- if (val2 != 0) {
- ret = -EINVAL;
- goto out;
- }
+ if (val2 != 0)
+ return -EINVAL;

- ret = adc->chip->set_offset(adc, channel->channel, val);
+ return adc->chip->set_offset(adc, channel->channel, val);
break;

case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
for (int i = 0; i < ARRAY_SIZE(mcp3911_osr_table); i++) {
if (val == mcp3911_osr_table[i]) {
- ret = adc->chip->set_osr(adc, i);
- break;
+ return adc->chip->set_osr(adc, i);
}
}
break;
}
-
-out:
- mutex_unlock(&adc->lock);
- return ret;
+ return -EINVAL;
}

static int mcp3911_calc_scale_table(struct mcp3911 *adc)
@@ -532,7 +516,7 @@ static irqreturn_t mcp3911_trigger_handler(int irq, void *p)
int i = 0;
int ret;

- mutex_lock(&adc->lock);
+ guard(mutex)(&adc->lock);
adc->tx_buf = MCP3911_REG_READ(MCP3911_CHANNEL(0), adc->dev_addr);
ret = spi_sync_transfer(adc->spi, xfer, ARRAY_SIZE(xfer));
if (ret < 0) {
@@ -549,7 +533,6 @@ static irqreturn_t mcp3911_trigger_handler(int irq, void *p)
iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
iio_get_time_ns(indio_dev));
out:
- mutex_unlock(&adc->lock);
iio_trigger_notify_done(indio_dev->trig);

return IRQ_HANDLED;

---
base-commit: 33cc938e65a98f1d29d0a18403dbbee050dcad9a
change-id: 20231125-mcp3911-guard-866591e2c947

Best regards,
--
Marcus Folkesson <[email protected]>

2023-12-06 18:01:59

by Jonathan Cameron

Subject: Re: [PATCH v3] iio: adc: mcp3911: simplify code with guard macro

On Tue, 05 Dec 2023 12:16:33 +0100
Marcus Folkesson <[email protected]> wrote:

> Use the guard(mutex) macro for handle mutex lock/unlocks.
>
> Signed-off-by: Marcus Folkesson <[email protected]>
Hi Marcus,

One follow up issue inline.

> ---
> Changes in v3:
> - Return early in good paths as well
> - Rebase against master
> - Link to v2: https://lore.kernel.org/r/[email protected]
>
> Changes in v2:
> - Return directly instead of goto label
> - Link to v1: https://lore.kernel.org/r/[email protected]
> ---
> drivers/iio/adc/mcp3911.c | 47 +++++++++++++++--------------------------------
> 1 file changed, 15 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
> index d864558bc087..f4822ecece89 100644
> --- a/drivers/iio/adc/mcp3911.c
> +++ b/drivers/iio/adc/mcp3911.c
> @@ -7,6 +7,7 @@
> */
> #include <linux/bitfield.h>
> #include <linux/bits.h>
> +#include <linux/cleanup.h>
> #include <linux/clk.h>
> #include <linux/delay.h>
> #include <linux/err.h>
> @@ -318,44 +319,34 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
> struct mcp3911 *adc = iio_priv(indio_dev);
> int ret = -EINVAL;
>
> - mutex_lock(&adc->lock);
> + guard(mutex)(&adc->lock);
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> ret = mcp3911_read(adc,
> MCP3911_CHANNEL(channel->channel), val, 3);
> if (ret)
> - goto out;
> + return ret;
>
> *val = sign_extend32(*val, 23);
> -
> - ret = IIO_VAL_INT;
> + return IIO_VAL_INT;
> break;
Why keep the break? It's unreachable code.
Same for other similar cases.

Jonathan


>