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* [PATCH] i2c: mux: Use struct_size() in devm_kzalloc()
@ 2019-05-29 16:20 Gustavo A. R. Silva
  2019-06-11  7:12 ` Peter Rosin
  0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2019-05-29 16:20 UTC (permalink / raw)
  To: Peter Rosin, Wolfram Sang; +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;
    struct boo entry[];
};

instance = devm_kzalloc(dev, sizeof(struct foo) + count * sizeof(struct boo), 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/i2c-mux.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 603252fa1284..8d5e4c6fdd8e 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -243,8 +243,7 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
 {
 	struct i2c_mux_core *muxc;
 
-	muxc = devm_kzalloc(dev, sizeof(*muxc)
-			    + max_adapters * sizeof(muxc->adapter[0])
+	muxc = devm_kzalloc(dev, struct_size(muxc, adapter, max_adapters)
 			    + sizeof_priv, GFP_KERNEL);
 	if (!muxc)
 		return NULL;
-- 
2.21.0


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] i2c: mux: Use struct_size() in devm_kzalloc()
  2019-05-29 16:20 [PATCH] i2c: mux: Use struct_size() in devm_kzalloc() Gustavo A. R. Silva
@ 2019-06-11  7:12 ` Peter Rosin
  0 siblings, 0 replies; 2+ messages in thread
From: Peter Rosin @ 2019-06-11  7:12 UTC (permalink / raw)
  To: Gustavo A. R. Silva, Wolfram Sang; +Cc: linux-i2c, linux-kernel

On 2019-05-29 18:20, Gustavo A. R. Silva wrote:
> 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;
>     struct boo entry[];
> };
> 
> instance = devm_kzalloc(dev, sizeof(struct foo) + count * sizeof(struct boo), 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.

Thanks, patch applied to i2c-mux/for-next

Cheers,
Peter

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2019-06-11  7:12 UTC | newest]

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2019-05-29 16:20 [PATCH] i2c: mux: Use struct_size() in devm_kzalloc() Gustavo A. R. Silva
2019-06-11  7:12 ` Peter Rosin

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