[PATCH] dma-mapping: Use 'bitmap_zalloc()' when applicable

[PATCH] dma-mapping: Use 'bitmap_zalloc()' when applicable

[Christophe JAILLET]

'dma_mem->bitmap' is a bitmap. So use 'bitmap_zalloc()' to simplify code,
improve the semantic and avoid some open-coded arithmetic in allocator
arguments.

Also change the corresponding 'kfree()' into 'bitmap_free()' to keep
consistency.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 kernel/dma/coherent.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index 25fc85a7aebe..375fb3c9538d 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -40,7 +40,6 @@ static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
 {
 	struct dma_coherent_mem *dma_mem;
 	int pages = size >> PAGE_SHIFT;
-	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
 	void *mem_base;
 
 	if (!size)
@@ -53,7 +52,7 @@ static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
 	dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
 	if (!dma_mem)
 		goto out_unmap_membase;
-	dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+	dma_mem->bitmap = bitmap_zalloc(pages, GFP_KERNEL);
 	if (!dma_mem->bitmap)
 		goto out_free_dma_mem;
 
@@ -81,7 +80,7 @@ static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
 		return;
 
 	memunmap(mem->virt_base);
-	kfree(mem->bitmap);
+	bitmap_free(mem->bitmap);
 	kfree(mem);
 }
 
-- 
2.30.2

Re: [PATCH] dma-mapping: Use 'bitmap_zalloc()' when applicable

[Joe Perches]

On Sun, 2021-10-24 at 19:40 +0200, Christophe JAILLET wrote:
> 'dma_mem->bitmap' is a bitmap. So use 'bitmap_zalloc()' to simplify code,
> improve the semantic and avoid some open-coded arithmetic in allocator
> arguments.

There is a cocci script for some of these.

https://lore.kernel.org/all/08b89608cfb1280624d1a89ead6547069f9a4c31.camel@perches.com/

Re: [PATCH] dma-mapping: Use 'bitmap_zalloc()' when applicable

[Christophe JAILLET]

Le 24/10/2021 à 19:54, Joe Perches a écrit :
> On Sun, 2021-10-24 at 19:40 +0200, Christophe JAILLET wrote:
>> 'dma_mem->bitmap' is a bitmap. So use 'bitmap_zalloc()' to simplify code,
>> improve the semantic and avoid some open-coded arithmetic in allocator
>> arguments.
> 
> There is a cocci script for some of these.
> 
> https://lore.kernel.org/all/08b89608cfb1280624d1a89ead6547069f9a4c31.camel@perches.com/
> 

Hi Joe,

yes I know.
As it is public, I guess that new comers may have seen it and want to 
propose patches based on your cocci script.

So, for now, I'm more focused on things that are not spotted by your 
script. I look for places where the size computation is not done within 
the kmalloc() or eq. function.

CJ

Re: [PATCH] dma-mapping: Use 'bitmap_zalloc()' when applicable

[Christoph Hellwig]

Thanks, applied.