Re: [PATCH] staging: iio: adc: ad7280a: check for devm_kasprint() failure

From: Joe Perches
Date: Mon Nov 26 2018 - 11:56:16 EST

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In reply to: Dan Carpenter: "Re: [PATCH] staging: iio: adc: ad7280a: check for devm_kasprint() failure"
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On Mon, 2018-11-26 at 16:26 +0300, Dan Carpenter wrote:
> On Mon, Nov 26, 2018 at 02:10:09PM +0100, Nicholas Mc Guire wrote:
> > On Mon, Nov 26, 2018 at 04:00:32PM +0300, Dan Carpenter wrote:
> > > On Mon, Nov 26, 2018 at 10:39:04AM +0100, Nicholas Mc Guire wrote:
> > > > devm_kasprintf() may return NULL on failure of internal allocation thus
> > > > the assignments to attr.name are not safe if not checked. On error
> > > > ad7280_attr_init() returns a negative return so -ENOMEM should be
> > > > OK here (passed on as return value of the probe function).
> > > >
> > > > Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
> > > > Fixes: 2051f25d2a26 ("iio: adc: New driver for AD7280A Lithium Ion Battery Monitoring System2")
> > > > ---
> > > >
> > > > Problem located with an experimental coccinelle script
> > > >
> > > > As using if(!st->iio_attr[cnt].dev_attr.attr.name) seamed quite
> > > > unreadable in this case the (var == NULL) variant was used. Not
> > > ^^
> > > Why two spaces?
> >
> > just a typo
> >
> > > > sure if there are objections against this (checkpatch.pl issues
> > > > a CHECK on this).
> > > >
> > >
> > > You should just follow checkpatch rules here. If you don't, someone
> > > else will just send a patch to make it checkpatch compliant. One thing
> > > you could do is at the start of the loop do:
> > >
> > > struct iio_dev_attr *attr = &st->iio_attr[cnt];
> > >
> > > Then it becomes:
> > >
> > > if (!attr->dev_attr.attr.name)
> > >
> > > It's slightly more readable that way. Keep in mind that we increment o
> > > cnt++ in the middle of the loop so you'll have to update attr as well.
> > >
> > My understanding was that CHECK: notes are not strict rules but
> > those that may vary from case to case.
>
> Checkpatch is just a script. It's not a genius or the king of the
> world.

Or, as someone once wrote, more sentient than a squirrel.

> I actually agree with checkpatch on this one but it's a minor thing.
> Sometimes a maintainer will get obsessed with minor things.

Like #include file ordering by length or alphabet

> Btw, when I get annoyed with checkpatch, I feel like it's pretty obvious
> I am correct. I'm not like other kernel developers who have debatable
> style preferences... ;)

Yup.

btw: Using temporaries like the below can reduce object
size a bit too. (allyesconfig)

$ size drivers/staging/iio/adc/ad7280a.o*
text data bss dec hex filename
16287 2848 896 20031 4e3f drivers/staging/iio/adc/ad7280a.o.new
16623 2848 896 20367 4f8f drivers/staging/iio/adc/ad7280a.o.old

---
drivers/staging/iio/adc/ad7280a.c | 116 ++++++++++++++++++--------------------
1 file changed, 56 insertions(+), 60 deletions(-)

diff --git a/drivers/staging/iio/adc/ad7280a.c b/drivers/staging/iio/adc/ad7280a.c
index 0bb9ab174f2a..1542285b492c 100644
--- a/drivers/staging/iio/adc/ad7280a.c
+++ b/drivers/staging/iio/adc/ad7280a.c
@@ -499,6 +499,7 @@ static const struct attribute_group ad7280_attrs_group = {
static int ad7280_channel_init(struct ad7280_state *st)
{
int dev, ch, cnt;
+ struct iio_chan_spec *chan;

st->channels = devm_kcalloc(&st->spi->dev, (st->slave_num + 1) * 12 + 2,
sizeof(*st->channels), GFP_KERNEL);
@@ -508,51 +509,52 @@ static int ad7280_channel_init(struct ad7280_state *st)
for (dev = 0, cnt = 0; dev <= st->slave_num; dev++)
for (ch = AD7280A_CELL_VOLTAGE_1; ch <= AD7280A_AUX_ADC_6;
ch++, cnt++) {
+ chan = &st->channels[cnt];
if (ch < AD7280A_AUX_ADC_1) {
- st->channels[cnt].type = IIO_VOLTAGE;
- st->channels[cnt].differential = 1;
- st->channels[cnt].channel = (dev * 6) + ch;
- st->channels[cnt].channel2 =
- st->channels[cnt].channel + 1;
+ chan->type = IIO_VOLTAGE;
+ chan->differential = 1;
+ chan->channel = (dev * 6) + ch;
+ chan->channel2 = chan->channel + 1;
} else {
- st->channels[cnt].type = IIO_TEMP;
- st->channels[cnt].channel = (dev * 6) + ch - 6;
+ chan->type = IIO_TEMP;
+ chan->channel = (dev * 6) + ch - 6;
}
- st->channels[cnt].indexed = 1;
- st->channels[cnt].info_mask_separate =
- BIT(IIO_CHAN_INFO_RAW);
- st->channels[cnt].info_mask_shared_by_type =
+ chan->indexed = 1;
+ chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+ chan->info_mask_shared_by_type =
BIT(IIO_CHAN_INFO_SCALE);
- st->channels[cnt].address =
- ad7280a_devaddr(dev) << 8 | ch;
- st->channels[cnt].scan_index = cnt;
- st->channels[cnt].scan_type.sign = 'u';
- st->channels[cnt].scan_type.realbits = 12;
- st->channels[cnt].scan_type.storagebits = 32;
- st->channels[cnt].scan_type.shift = 0;
+ chan->address = ad7280a_devaddr(dev) << 8 | ch;
+ chan->scan_index = cnt;
+ chan->scan_type.sign = 'u';
+ chan->scan_type.realbits = 12;
+ chan->scan_type.storagebits = 32;
+ chan->scan_type.shift = 0;
}

- st->channels[cnt].type = IIO_VOLTAGE;
- st->channels[cnt].differential = 1;
- st->channels[cnt].channel = 0;
- st->channels[cnt].channel2 = dev * 6;
- st->channels[cnt].address = AD7280A_ALL_CELLS;
- st->channels[cnt].indexed = 1;
- st->channels[cnt].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
- st->channels[cnt].info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
- st->channels[cnt].scan_index = cnt;
- st->channels[cnt].scan_type.sign = 'u';
- st->channels[cnt].scan_type.realbits = 32;
- st->channels[cnt].scan_type.storagebits = 32;
- st->channels[cnt].scan_type.shift = 0;
+ chan = &st->channels[cnt];
+ chan->type = IIO_VOLTAGE;
+ chan->differential = 1;
+ chan->channel = 0;
+ chan->channel2 = dev * 6;
+ chan->address = AD7280A_ALL_CELLS;
+ chan->indexed = 1;
+ chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+ chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
+ chan->scan_index = cnt;
+ chan->scan_type.sign = 'u';
+ chan->scan_type.realbits = 32;
+ chan->scan_type.storagebits = 32;
+ chan->scan_type.shift = 0;
+
cnt++;
- st->channels[cnt].type = IIO_TIMESTAMP;
- st->channels[cnt].channel = -1;
- st->channels[cnt].scan_index = cnt;
- st->channels[cnt].scan_type.sign = 's';
- st->channels[cnt].scan_type.realbits = 64;
- st->channels[cnt].scan_type.storagebits = 64;
- st->channels[cnt].scan_type.shift = 0;
+ chan = &st->channels[cnt];
+ chan->type = IIO_TIMESTAMP;
+ chan->channel = -1;
+ chan->scan_index = cnt;
+ chan->scan_type.sign = 's';
+ chan->scan_type.realbits = 64;
+ chan->scan_type.storagebits = 64;
+ chan->scan_type.shift = 0;

return cnt + 1;
}
@@ -561,6 +563,7 @@ static int ad7280_attr_init(struct ad7280_state *st)
{
int dev, ch, cnt;
unsigned int index;
+ struct iio_dev_attr *iio;

st->iio_attr = devm_kcalloc(&st->spi->dev, 2, sizeof(*st->iio_attr) *
(st->slave_num + 1) * AD7280A_CELLS_PER_DEV,
@@ -571,37 +574,30 @@ static int ad7280_attr_init(struct ad7280_state *st)
for (dev = 0, cnt = 0; dev <= st->slave_num; dev++)
for (ch = AD7280A_CELL_VOLTAGE_1; ch <= AD7280A_CELL_VOLTAGE_6;
ch++, cnt++) {
+ iio = &st->iio_attr[cnt];
index = dev * AD7280A_CELLS_PER_DEV + ch;
- st->iio_attr[cnt].address =
- ad7280a_devaddr(dev) << 8 | ch;
- st->iio_attr[cnt].dev_attr.attr.mode =
- 0644;
- st->iio_attr[cnt].dev_attr.show =
- ad7280_show_balance_sw;
- st->iio_attr[cnt].dev_attr.store =
- ad7280_store_balance_sw;
- st->iio_attr[cnt].dev_attr.attr.name =
+ iio->address = ad7280a_devaddr(dev) << 8 | ch;
+ iio->dev_attr.attr.mode = 0644;
+ iio->dev_attr.show = ad7280_show_balance_sw;
+ iio->dev_attr.store = ad7280_store_balance_sw;
+ iio->dev_attr.attr.name =
devm_kasprintf(&st->spi->dev, GFP_KERNEL,
"in%d-in%d_balance_switch_en",
index, index + 1);
- ad7280_attributes[cnt] =
- &st->iio_attr[cnt].dev_attr.attr;
+ ad7280_attributes[cnt] = &iio->dev_attr.attr;
+
cnt++;
- st->iio_attr[cnt].address =
- ad7280a_devaddr(dev) << 8 |
+ iio = &st->iio_attr[cnt];
+ iio->address = ad7280a_devaddr(dev) << 8 |
(AD7280A_CB1_TIMER + ch);
- st->iio_attr[cnt].dev_attr.attr.mode =
- 0644;
- st->iio_attr[cnt].dev_attr.show =
- ad7280_show_balance_timer;
- st->iio_attr[cnt].dev_attr.store =
- ad7280_store_balance_timer;
- st->iio_attr[cnt].dev_attr.attr.name =
+ iio->dev_attr.attr.mode = 0644;
+ iio->dev_attr.show = ad7280_show_balance_timer;
+ iio->dev_attr.store = ad7280_store_balance_timer;
+ iio->dev_attr.attr.name =
devm_kasprintf(&st->spi->dev, GFP_KERNEL,
"in%d-in%d_balance_timer",
index, index + 1);
- ad7280_attributes[cnt] =
- &st->iio_attr[cnt].dev_attr.attr;
+ ad7280_attributes[cnt] = &iio->dev_attr.attr;
}

ad7280_attributes[cnt] = NULL;

Next message: Andrea Parri: "Re: [PATCH 2/4] fscache: Fix race in fscache_op_complete() due to split atomic_sub & read"
Previous message: David Lechner: "Re: [PATCH 15/17] ARM: dts: AM33xx: Add the PRU-ICSS DT nodes"
In reply to: Dan Carpenter: "Re: [PATCH] staging: iio: adc: ad7280a: check for devm_kasprint() failure"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]