[v1] i2c: atr: use kzalloc_flex

[PATCH] i2c: atr: use kzalloc_flex

Posted by Rosen Penev 3 weeks, 4 days ago

Convert kzalloc_obj + kcalloc to kzalloc_flex to save an allocation.

Add __counted_by to get extra runtime analysis. Move counting variable
assignment immediately after allocation as required by __counted_by.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/i2c/i2c-atr.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/i2c/i2c-atr.c b/drivers/i2c/i2c-atr.c
index f9fcb4793aaf..b0aedcf0bf71 100644
--- a/drivers/i2c/i2c-atr.c
+++ b/drivers/i2c/i2c-atr.c
@@ -58,8 +58,8 @@ struct i2c_atr_alias_pool {
 
 	/* Protects aliases and use_mask */
 	spinlock_t lock;
-	u16 *aliases;
 	unsigned long *use_mask;
+	u16 aliases[] __counted_by(size);
 };
 
 /**
@@ -137,22 +137,16 @@ static struct i2c_atr_alias_pool *i2c_atr_alloc_alias_pool(size_t num_aliases, b
 	struct i2c_atr_alias_pool *alias_pool;
 	int ret;
 
-	alias_pool = kzalloc_obj(*alias_pool);
+	alias_pool = kzalloc_flex(*alias_pool, aliases, num_aliases);
 	if (!alias_pool)
 		return ERR_PTR(-ENOMEM);
 
 	alias_pool->size = num_aliases;
 
-	alias_pool->aliases = kcalloc(num_aliases, sizeof(*alias_pool->aliases), GFP_KERNEL);
-	if (!alias_pool->aliases) {
-		ret = -ENOMEM;
-		goto err_free_alias_pool;
-	}
-
 	alias_pool->use_mask = bitmap_zalloc(num_aliases, GFP_KERNEL);
 	if (!alias_pool->use_mask) {
 		ret = -ENOMEM;
-		goto err_free_aliases;
+		goto err_free_alias_pool;
 	}
 
 	alias_pool->shared = shared;
@@ -161,8 +155,6 @@ static struct i2c_atr_alias_pool *i2c_atr_alloc_alias_pool(size_t num_aliases, b
 
 	return alias_pool;
 
-err_free_aliases:
-	kfree(alias_pool->aliases);
 err_free_alias_pool:
 	kfree(alias_pool);
 	return ERR_PTR(ret);
@@ -171,7 +163,6 @@ static struct i2c_atr_alias_pool *i2c_atr_alloc_alias_pool(size_t num_aliases, b
 static void i2c_atr_free_alias_pool(struct i2c_atr_alias_pool *alias_pool)
 {
 	bitmap_free(alias_pool->use_mask);
-	kfree(alias_pool->aliases);
 	kfree(alias_pool);
 }
 
-- 
2.53.0

Re: [PATCH] i2c: atr: use kzalloc_flex

Posted by Romain Gantois 1 week, 1 day ago

Hello Rosen,

On Friday, 13 March 2026 01:23:08 CEST Rosen Penev wrote:
> Convert kzalloc_obj + kcalloc to kzalloc_flex to save an allocation.
> 
> Add __counted_by to get extra runtime analysis. Move counting variable
> assignment immediately after allocation as required by __counted_by.
> 
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
> 
>  drivers/i2c/i2c-atr.c | 15 +++------------
>  1 file changed, 3 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-atr.c b/drivers/i2c/i2c-atr.c
> index f9fcb4793aaf..b0aedcf0bf71 100644
> --- a/drivers/i2c/i2c-atr.c
> +++ b/drivers/i2c/i2c-atr.c
> @@ -58,8 +58,8 @@ struct i2c_atr_alias_pool {
> 
>  	/* Protects aliases and use_mask */
>  	spinlock_t lock;
> 
> -	u16 *aliases;
> 
>  	unsigned long *use_mask;
> 
> +	u16 aliases[] __counted_by(size);
> 
>  };
>  
>  /**
> 
> @@ -137,22 +137,16 @@ static struct i2c_atr_alias_pool
> *i2c_atr_alloc_alias_pool(size_t num_aliases, b struct i2c_atr_alias_pool
> *alias_pool;
> 
>  	int ret;
> 
> -	alias_pool = kzalloc_obj(*alias_pool);
> +	alias_pool = kzalloc_flex(*alias_pool, aliases, num_aliases);
> 
>  	if (!alias_pool)
>  	
>  		return ERR_PTR(-ENOMEM);
>  	
>  	alias_pool->size = num_aliases;
> 
> -	alias_pool->aliases = kcalloc(num_aliases, sizeof(*alias_pool->aliases),
> GFP_KERNEL); -	if (!alias_pool->aliases) {
> -		ret = -ENOMEM;
> -		goto err_free_alias_pool;
> -	}
> -
> 
>  	alias_pool->use_mask = bitmap_zalloc(num_aliases, GFP_KERNEL);
>  	if (!alias_pool->use_mask) {
>  	
>  		ret = -ENOMEM;
> 
> -		goto err_free_aliases;
> +		goto err_free_alias_pool;
> 
>  	}
>  	
>  	alias_pool->shared = shared;
> 
> @@ -161,8 +155,6 @@ static struct i2c_atr_alias_pool
> *i2c_atr_alloc_alias_pool(size_t num_aliases, b
> 
>  	return alias_pool;
> 
> -err_free_aliases:
> -	kfree(alias_pool->aliases);
> 
>  err_free_alias_pool:
>  	kfree(alias_pool);
>  	return ERR_PTR(ret);
> 
> @@ -171,7 +163,6 @@ static struct i2c_atr_alias_pool
> *i2c_atr_alloc_alias_pool(size_t num_aliases, b static void
> i2c_atr_free_alias_pool(struct i2c_atr_alias_pool *alias_pool) {
> 
>  	bitmap_free(alias_pool->use_mask);
> 
> -	kfree(alias_pool->aliases);
> 
>  	kfree(alias_pool);
>  
>  }

Reviewed-by: Romain Gantois <romain.gantois@bootlin.com>

Re: [PATCH] i2c: atr: use kzalloc_flex

Posted by Luca Ceresoli 3 weeks, 4 days ago

Hello Rosen,

On Fri Mar 13, 2026 at 1:23 AM CET, Rosen Penev wrote:
> Convert kzalloc_obj + kcalloc to kzalloc_flex to save an allocation.
>
> Add __counted_by to get extra runtime analysis. Move counting variable
> assignment immediately after allocation as required by __counted_by.

Not sure what you mean by the last sentence, you are not moving the
assignment.

> --- a/drivers/i2c/i2c-atr.c
> +++ b/drivers/i2c/i2c-atr.c
> @@ -58,8 +58,8 @@ struct i2c_atr_alias_pool {
>
>  	/* Protects aliases and use_mask */
>  	spinlock_t lock;
> -	u16 *aliases;
>  	unsigned long *use_mask;
> +	u16 aliases[] __counted_by(size);

Please reorder the parameters accordingly in the kdoc documentation above.

> @@ -137,22 +137,16 @@ static struct i2c_atr_alias_pool *i2c_atr_alloc_alias_pool(size_t num_aliases, b
>  	struct i2c_atr_alias_pool *alias_pool;
>  	int ret;
>
> -	alias_pool = kzalloc_obj(*alias_pool);
> +	alias_pool = kzalloc_flex(*alias_pool, aliases, num_aliases);
>  	if (!alias_pool)
>  		return ERR_PTR(-ENOMEM);
>
>  	alias_pool->size = num_aliases;

I'm not really sure about that, but I suspect kzalloc_flex() does set the
counter variable automatically if it's annotated using __counted_by. If
that's true, you can drop this line.

Otherwise LGTM.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH] i2c: atr: use kzalloc_flex

Posted by Rosen Penev 3 weeks, 3 days ago

On Fri, Mar 13, 2026 at 1:23 AM Luca Ceresoli <luca.ceresoli@bootlin.com> wrote:
>
> Hello Rosen,
>
> On Fri Mar 13, 2026 at 1:23 AM CET, Rosen Penev wrote:
> > Convert kzalloc_obj + kcalloc to kzalloc_flex to save an allocation.
> >
> > Add __counted_by to get extra runtime analysis. Move counting variable
> > assignment immediately after allocation as required by __counted_by.
>
> Not sure what you mean by the last sentence, you are not moving the
> assignment.
Yeah, will remove.
>
> > --- a/drivers/i2c/i2c-atr.c
> > +++ b/drivers/i2c/i2c-atr.c
> > @@ -58,8 +58,8 @@ struct i2c_atr_alias_pool {
> >
> >       /* Protects aliases and use_mask */
> >       spinlock_t lock;
> > -     u16 *aliases;
> >       unsigned long *use_mask;
> > +     u16 aliases[] __counted_by(size);
>
> Please reorder the parameters accordingly in the kdoc documentation above.
Will do.
>
> > @@ -137,22 +137,16 @@ static struct i2c_atr_alias_pool *i2c_atr_alloc_alias_pool(size_t num_aliases, b
> >       struct i2c_atr_alias_pool *alias_pool;
> >       int ret;
> >
> > -     alias_pool = kzalloc_obj(*alias_pool);
> > +     alias_pool = kzalloc_flex(*alias_pool, aliases, num_aliases);
> >       if (!alias_pool)
> >               return ERR_PTR(-ENOMEM);
> >
> >       alias_pool->size = num_aliases;
>
> I'm not really sure about that, but I suspect kzalloc_flex() does set the
> counter variable automatically if it's annotated using __counted_by. If
> that's true, you can drop this line.
It's automatic with GCC15+.
>
> Otherwise LGTM.
>
> Luca
>
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com