sparc: use struct_size() in kzalloc()

Message ID 20190108161356.GA23617@embeddedor
State Accepted
Delegated to: David Miller
Headers show
Series
  • sparc: use struct_size() in kzalloc()
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Commit Message

Gustavo A. R. Silva Jan. 8, 2019, 4:13 p.m.
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 = kzalloc(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 = kzalloc(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>
---
 arch/sparc/kernel/cpumap.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

David Miller Feb. 26, 2019, 12:37 a.m. | #1
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Tue, 8 Jan 2019 10:13:56 -0600

> 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 = kzalloc(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 = kzalloc(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>

Applied.
Gustavo A. R. Silva April 10, 2019, 7:05 p.m. | #2
Hi Dave,

I wonder if you can take this.

Thanks
--
Gustavo

On 1/8/19 10:13 AM, 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;
>     void *entry[];
> };
> 
> instance = kzalloc(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 = kzalloc(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>
> ---
>  arch/sparc/kernel/cpumap.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/sparc/kernel/cpumap.c b/arch/sparc/kernel/cpumap.c
> index d1d52822603d..1cb62bfeaa1f 100644
> --- a/arch/sparc/kernel/cpumap.c
> +++ b/arch/sparc/kernel/cpumap.c
> @@ -194,8 +194,7 @@ static struct cpuinfo_tree *build_cpuinfo_tree(void)
>  
>  	n = enumerate_cpuinfo_nodes(tmp_level);
>  
> -	new_tree = kzalloc(sizeof(struct cpuinfo_tree) +
> -	                   (sizeof(struct cpuinfo_node) * n), GFP_ATOMIC);
> +	new_tree = kzalloc(struct_size(new_tree, nodes, n), GFP_ATOMIC);
>  	if (!new_tree)
>  		return NULL;
>  
>

Patch

diff --git a/arch/sparc/kernel/cpumap.c b/arch/sparc/kernel/cpumap.c
index d1d52822603d..1cb62bfeaa1f 100644
--- a/arch/sparc/kernel/cpumap.c
+++ b/arch/sparc/kernel/cpumap.c
@@ -194,8 +194,7 @@  static struct cpuinfo_tree *build_cpuinfo_tree(void)
 
 	n = enumerate_cpuinfo_nodes(tmp_level);
 
-	new_tree = kzalloc(sizeof(struct cpuinfo_tree) +
-	                   (sizeof(struct cpuinfo_node) * n), GFP_ATOMIC);
+	new_tree = kzalloc(struct_size(new_tree, nodes, n), GFP_ATOMIC);
 	if (!new_tree)
 		return NULL;