[v2] dma-buf: heaps: Support carved-out heaps

[PATCH v2 1/2] dma-buf: heaps: system: Remove global variable

Posted by Maxime Ripard 1 week, 2 days ago

The system heap has been using its struct dma_heap pointer but wasn't
using it anywhere.

Since we'll need additional parameters to attach to that heap type,
let's create a private structure and set it as the dma_heap drvdata,
removing the global variable in the process.

Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
 drivers/dma-buf/heaps/system_heap.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index 26d5dc89ea1663a0d078e3a5723ca3d8d12b935f..adf422eaa33a52794f952d9d4260b8743d37f421 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -19,11 +19,13 @@
 #include <linux/module.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 
-static struct dma_heap *sys_heap;
+struct system_heap {
+	struct dma_heap *heap;
+};
 
 struct system_heap_buffer {
 	struct dma_heap *heap;
 	struct list_head attachments;
 	struct mutex lock;
@@ -422,17 +424,22 @@ static const struct dma_heap_ops system_heap_ops = {
 };
 
 static int __init system_heap_create(void)
 {
 	struct dma_heap_export_info exp_info;
+	struct system_heap *sys_heap;
+
+	sys_heap = kzalloc(sizeof(*sys_heap), GFP_KERNEL);
+	if (!sys_heap)
+		return -ENOMEM;
 
 	exp_info.name = "system";
 	exp_info.ops = &system_heap_ops;
-	exp_info.priv = NULL;
+	exp_info.priv = sys_heap;
 
-	sys_heap = dma_heap_add(&exp_info);
-	if (IS_ERR(sys_heap))
-		return PTR_ERR(sys_heap);
+	sys_heap->heap = dma_heap_add(&exp_info);
+	if (IS_ERR(sys_heap->heap))
+		return PTR_ERR(sys_heap->heap);
 
 	return 0;
 }
 module_init(system_heap_create);

-- 
2.49.0

Re: [PATCH v2 1/2] dma-buf: heaps: system: Remove global variable

Posted by Christian König 1 week, 2 days ago


Am 01.04.25 um 17:12 schrieb Maxime Ripard:
> The system heap has been using its struct dma_heap pointer but wasn't
> using it anywhere.
>
> Since we'll need additional parameters to attach to that heap type,
> let's create a private structure and set it as the dma_heap drvdata,
> removing the global variable in the process.
>
> Signed-off-by: Maxime Ripard <mripard@kernel.org>
> ---
>  drivers/dma-buf/heaps/system_heap.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> index 26d5dc89ea1663a0d078e3a5723ca3d8d12b935f..adf422eaa33a52794f952d9d4260b8743d37f421 100644
> --- a/drivers/dma-buf/heaps/system_heap.c
> +++ b/drivers/dma-buf/heaps/system_heap.c
> @@ -19,11 +19,13 @@
>  #include <linux/module.h>
>  #include <linux/scatterlist.h>
>  #include <linux/slab.h>
>  #include <linux/vmalloc.h>
>  
> -static struct dma_heap *sys_heap;
> +struct system_heap {
> +	struct dma_heap *heap;
> +};
>  
>  struct system_heap_buffer {
>  	struct dma_heap *heap;
>  	struct list_head attachments;
>  	struct mutex lock;
> @@ -422,17 +424,22 @@ static const struct dma_heap_ops system_heap_ops = {
>  };
>  
>  static int __init system_heap_create(void)
>  {
>  	struct dma_heap_export_info exp_info;
> +	struct system_heap *sys_heap;
> +
> +	sys_heap = kzalloc(sizeof(*sys_heap), GFP_KERNEL);
> +	if (!sys_heap)
> +		return -ENOMEM;
>  
>  	exp_info.name = "system";
>  	exp_info.ops = &system_heap_ops;
> -	exp_info.priv = NULL;
> +	exp_info.priv = sys_heap;

Why do you even need this?

>  
> -	sys_heap = dma_heap_add(&exp_info);
> -	if (IS_ERR(sys_heap))
> -		return PTR_ERR(sys_heap);
> +	sys_heap->heap = dma_heap_add(&exp_info);
> +	if (IS_ERR(sys_heap->heap))
> +		return PTR_ERR(sys_heap->heap);

That's clearly missing freeing sys_heap again.

Christian.

>  
>  	return 0;
>  }
>  module_init(system_heap_create);
>

Re: [PATCH v2 1/2] dma-buf: heaps: system: Remove global variable

Posted by Maxime Ripard 1 week ago

On Tue, Apr 01, 2025 at 05:28:43PM +0200, Christian König wrote:
> 
> 
> Am 01.04.25 um 17:12 schrieb Maxime Ripard:
> > The system heap has been using its struct dma_heap pointer but wasn't
> > using it anywhere.
> >
> > Since we'll need additional parameters to attach to that heap type,
> > let's create a private structure and set it as the dma_heap drvdata,
> > removing the global variable in the process.
> >
> > Signed-off-by: Maxime Ripard <mripard@kernel.org>
> > ---
> >  drivers/dma-buf/heaps/system_heap.c | 17 ++++++++++++-----
> >  1 file changed, 12 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> > index 26d5dc89ea1663a0d078e3a5723ca3d8d12b935f..adf422eaa33a52794f952d9d4260b8743d37f421 100644
> > --- a/drivers/dma-buf/heaps/system_heap.c
> > +++ b/drivers/dma-buf/heaps/system_heap.c
> > @@ -19,11 +19,13 @@
> >  #include <linux/module.h>
> >  #include <linux/scatterlist.h>
> >  #include <linux/slab.h>
> >  #include <linux/vmalloc.h>
> >  
> > -static struct dma_heap *sys_heap;
> > +struct system_heap {
> > +	struct dma_heap *heap;
> > +};
> >  
> >  struct system_heap_buffer {
> >  	struct dma_heap *heap;
> >  	struct list_head attachments;
> >  	struct mutex lock;
> > @@ -422,17 +424,22 @@ static const struct dma_heap_ops system_heap_ops = {
> >  };
> >  
> >  static int __init system_heap_create(void)
> >  {
> >  	struct dma_heap_export_info exp_info;
> > +	struct system_heap *sys_heap;
> > +
> > +	sys_heap = kzalloc(sizeof(*sys_heap), GFP_KERNEL);
> > +	if (!sys_heap)
> > +		return -ENOMEM;
> >  
> >  	exp_info.name = "system";
> >  	exp_info.ops = &system_heap_ops;
> > -	exp_info.priv = NULL;
> > +	exp_info.priv = sys_heap;
> 
> Why do you even need this?

Urgh, sorry. I'm not even sure how I ended up with that patch, but
you're correct. I'll send a much simpler version.

Maxime