* [PATCH] i2c: mux: demux-pinctrl: use struct_size() in devm_kzalloc()
@ 2019-01-04 17:43 Gustavo A. R. Silva
2019-01-04 18:06 ` Wolfram Sang
0 siblings, 1 reply; 4+ messages in thread
From: Gustavo A. R. Silva @ 2019-01-04 17:43 UTC (permalink / raw)
To: Wolfram Sang, Peter Rosin; +Cc: linux-i2c, linux-kernel, Gustavo A. R. Silva
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct foo {
int stuff;
void *entry[];
};
instance = devm_kzalloc(dev, sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:
instance = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/i2c/muxes/i2c-demux-pinctrl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
index 035032e20327..012b45e447c3 100644
--- a/drivers/i2c/muxes/i2c-demux-pinctrl.c
+++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
@@ -219,8 +219,8 @@ static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
return -EINVAL;
}
- priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
- + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);
+ priv = devm_kzalloc(&pdev->dev, struct_size(priv, chan, num_chan),
+ GFP_KERNEL);
props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);
--
2.20.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] i2c: mux: demux-pinctrl: use struct_size() in devm_kzalloc()
2019-01-04 17:43 [PATCH] i2c: mux: demux-pinctrl: use struct_size() in devm_kzalloc() Gustavo A. R. Silva
@ 2019-01-04 18:06 ` Wolfram Sang
2019-04-21 18:15 ` Peter Rosin
0 siblings, 1 reply; 4+ messages in thread
From: Wolfram Sang @ 2019-01-04 18:06 UTC (permalink / raw)
To: Gustavo A. R. Silva; +Cc: Wolfram Sang, Peter Rosin, linux-i2c, linux-kernel
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> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
I am okay with this patch in general. However, I think the name of the
helper 'struct_size' is a bit unfortunate. I really wondered on the
first read why it needs 3 arguments to find out a struct size. I only
understood on the second read. I think 'trailing_array_struct_size'
would be way more clearer what it does.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] i2c: mux: demux-pinctrl: use struct_size() in devm_kzalloc()
2019-01-04 18:06 ` Wolfram Sang
@ 2019-04-21 18:15 ` Peter Rosin
2019-04-22 7:20 ` Wolfram Sang
0 siblings, 1 reply; 4+ messages in thread
From: Peter Rosin @ 2019-04-21 18:15 UTC (permalink / raw)
To: Wolfram Sang, Gustavo A. R. Silva; +Cc: Wolfram Sang, linux-i2c, linux-kernel
On 2019-01-04 19:06, Wolfram Sang wrote:
>
>> Instead of leaving these open-coded and prone to type mistakes, we can
>> now use the new struct_size() helper:
>
> I am okay with this patch in general. However, I think the name of the
> helper 'struct_size' is a bit unfortunate. I really wondered on the
> first read why it needs 3 arguments to find out a struct size. I only
> understood on the second read. I think 'trailing_array_struct_size'
> would be way more clearer what it does.
I read that as an Acked-by... :-)
Cheers,
Peter
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] i2c: mux: demux-pinctrl: use struct_size() in devm_kzalloc()
2019-04-21 18:15 ` Peter Rosin
@ 2019-04-22 7:20 ` Wolfram Sang
0 siblings, 0 replies; 4+ messages in thread
From: Wolfram Sang @ 2019-04-22 7:20 UTC (permalink / raw)
To: Peter Rosin; +Cc: Gustavo A. R. Silva, Wolfram Sang, linux-i2c, linux-kernel
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On Sun, Apr 21, 2019 at 06:15:21PM +0000, Peter Rosin wrote:
> On 2019-01-04 19:06, Wolfram Sang wrote:
> >
> >> Instead of leaving these open-coded and prone to type mistakes, we can
> >> now use the new struct_size() helper:
> >
> > I am okay with this patch in general. However, I think the name of the
> > helper 'struct_size' is a bit unfortunate. I really wondered on the
> > first read why it needs 3 arguments to find out a struct size. I only
> > understood on the second read. I think 'trailing_array_struct_size'
> > would be way more clearer what it does.
>
> I read that as an Acked-by... :-)
For this patch, yes. Thanks!
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-01-04 17:43 [PATCH] i2c: mux: demux-pinctrl: use struct_size() in devm_kzalloc() Gustavo A. R. Silva
2019-01-04 18:06 ` Wolfram Sang
2019-04-21 18:15 ` Peter Rosin
2019-04-22 7:20 ` Wolfram Sang
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