[PATCH] drivers: Use kzalloc instead of 'kmalloc+memset', where possible.

[PATCH] drivers: Use kzalloc instead of 'kmalloc+memset', where possible.

[Rakib Mullick]

Following patch removes the uses of 'kmalloc+memset' from various drivers subsystems, which is replaced by kzalloc. kzalloc take care of setting allocated memory with null, so it helps to get rid from using memset.


Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
---

diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
index 1c4b3aa..168b78f 100644
--- a/drivers/ata/sata_dwc_460ex.c
+++ b/drivers/ata/sata_dwc_460ex.c
@@ -1638,13 +1638,12 @@ static int sata_dwc_probe(struct platform_device *ofdev)
 	const struct ata_port_info *ppi[] = { &pi, NULL };
 
 	/* Allocate DWC SATA device */
-	hsdev = kmalloc(sizeof(*hsdev), GFP_KERNEL);
+	hsdev = kzalloc(sizeof(*hsdev), GFP_KERNEL);
 	if (hsdev == NULL) {
 		dev_err(&ofdev->dev, "kmalloc failed for hsdev\n");
 		err = -ENOMEM;
 		goto error_out;
 	}
-	memset(hsdev, 0, sizeof(*hsdev));
 
 	/* Ioremap SATA registers */
 	base = of_iomap(ofdev->dev.of_node, 0);
diff --git a/drivers/gpu/drm/drm_scatter.c b/drivers/gpu/drm/drm_scatter.c
index d15e09b..37db1f8 100644
--- a/drivers/gpu/drm/drm_scatter.c
+++ b/drivers/gpu/drm/drm_scatter.c
@@ -83,30 +83,26 @@ int drm_sg_alloc(struct drm_device *dev, struct drm_scatter_gather * request)
 	if (dev->sg)
 		return -EINVAL;
 
-	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry)
 		return -ENOMEM;
 
-	memset(entry, 0, sizeof(*entry));
 	pages = (request->size + PAGE_SIZE - 1) / PAGE_SIZE;
 	DRM_DEBUG("size=%ld pages=%ld\n", request->size, pages);
 
 	entry->pages = pages;
-	entry->pagelist = kmalloc(pages * sizeof(*entry->pagelist), GFP_KERNEL);
+	entry->pagelist = kzalloc(pages * sizeof(*entry->pagelist), GFP_KERNEL);
 	if (!entry->pagelist) {
 		kfree(entry);
 		return -ENOMEM;
 	}
 
-	memset(entry->pagelist, 0, pages * sizeof(*entry->pagelist));
-
-	entry->busaddr = kmalloc(pages * sizeof(*entry->busaddr), GFP_KERNEL);
+	entry->busaddr = kzalloc(pages * sizeof(*entry->busaddr), GFP_KERNEL);
 	if (!entry->busaddr) {
 		kfree(entry->pagelist);
 		kfree(entry);
 		return -ENOMEM;
 	}
-	memset((void *)entry->busaddr, 0, pages * sizeof(*entry->busaddr));
 
 	entry->virtual = drm_vmalloc_dma(pages << PAGE_SHIFT);
 	if (!entry->virtual) {
diff --git a/drivers/gpu/drm/radeon/radeon_mem.c b/drivers/gpu/drm/radeon/radeon_mem.c
index ed95155..988548e 100644
--- a/drivers/gpu/drm/radeon/radeon_mem.c
+++ b/drivers/gpu/drm/radeon/radeon_mem.c
@@ -139,7 +139,7 @@ static int init_heap(struct mem_block **heap, int start, int size)
 	if (!blocks)
 		return -ENOMEM;
 
-	*heap = kmalloc(sizeof(**heap), GFP_KERNEL);
+	*heap = kzalloc(sizeof(**heap), GFP_KERNEL);
 	if (!*heap) {
 		kfree(blocks);
 		return -ENOMEM;
@@ -150,7 +150,6 @@ static int init_heap(struct mem_block **heap, int start, int size)
 	blocks->file_priv = NULL;
 	blocks->next = blocks->prev = *heap;
 
-	memset(*heap, 0, sizeof(**heap));
 	(*heap)->file_priv = (struct drm_file *) - 1;
 	(*heap)->next = (*heap)->prev = blocks;
 	return 0;
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c b/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c
index f1a52f9..07ce02d 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c
@@ -585,11 +585,10 @@ int vmw_overlay_init(struct vmw_private *dev_priv)
 		return -ENOSYS;
 	}
 
-	overlay = kmalloc(sizeof(*overlay), GFP_KERNEL);
+	overlay = kzalloc(sizeof(*overlay), GFP_KERNEL);
 	if (!overlay)
 		return -ENOMEM;
 
-	memset(overlay, 0, sizeof(*overlay));
 	mutex_init(&overlay->mutex);
 	for (i = 0; i < VMW_MAX_NUM_STREAMS; i++) {
 		overlay->stream[i].buf = NULL;
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index 5408b1b..bfe1bcc 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -612,11 +612,9 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
 	    srf->sizes[0].height == 64 &&
 	    srf->format == SVGA3D_A8R8G8B8) {
 
-		srf->snooper.image = kmalloc(64 * 64 * 4, GFP_KERNEL);
-		/* clear the image */
-		if (srf->snooper.image) {
-			memset(srf->snooper.image, 0x00, 64 * 64 * 4);
-		} else {
+		/* allocate image area and clear it */
+		srf->snooper.image = kzalloc(64 * 64 * 4, GFP_KERNEL);
+		if (!srf->snooper.image) {
 			DRM_ERROR("Failed to allocate cursor_image\n");
 			ret = -ENOMEM;
 			goto out_err1;
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index be8d4cb..370de0b 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -1094,10 +1094,9 @@ static int vga_arb_open(struct inode *inode, struct file *file)
 
 	pr_debug("%s\n", __func__);
 
-	priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (priv == NULL)
 		return -ENOMEM;
-	memset(priv, 0, sizeof(*priv));
 	spin_lock_init(&priv->lock);
 	file->private_data = priv;
 

Re: [PATCH] drivers: Use kzalloc instead of 'kmalloc+memset', where possible.

[Joe Perches]

On Mon, 2011-05-23 at 23:40 +0600, Rakib Mullick wrote:
> Following patch removes the uses of 'kmalloc+memset' from various
> drivers subsystems, which is replaced by kzalloc. kzalloc take care of
> setting allocated memory with null, so it helps to get rid from using
> memset.
> diff --git a/drivers/gpu/drm/drm_scatter.c b/drivers/gpu/drm/drm_scatter.c
[]
> -	entry->pagelist = kmalloc(pages * sizeof(*entry->pagelist), GFP_KERNEL);
> +	entry->pagelist = kzalloc(pages * sizeof(*entry->pagelist), GFP_KERNEL);

Perhaps it's better to use:

	entry->pagelist =  kcalloc(pages, sizeof(*entry->pagelist), GFP_KERNEL);

> -	entry->busaddr = kmalloc(pages * sizeof(*entry->busaddr), GFP_KERNEL);
> +	entry->busaddr = kzalloc(pages * sizeof(*entry->busaddr), GFP_KERNEL);

here too.

Re: [PATCH] drivers: Use kzalloc instead of 'kmalloc+memset', where possible.

[Rakib Mullick]

On 5/23/11, Joe Perches <joe@perches.com> wrote:
> On Mon, 2011-05-23 at 23:40 +0600, Rakib Mullick wrote:
>> Following patch removes the uses of 'kmalloc+memset' from various
>> drivers subsystems, which is replaced by kzalloc. kzalloc take care of
>> setting allocated memory with null, so it helps to get rid from using
>> memset.
>> diff --git a/drivers/gpu/drm/drm_scatter.c b/drivers/gpu/drm/drm_scatter.c
> []
>> -	entry->pagelist = kmalloc(pages * sizeof(*entry->pagelist), GFP_KERNEL);
>> +	entry->pagelist = kzalloc(pages * sizeof(*entry->pagelist), GFP_KERNEL);
>
> Perhaps it's better to use:
>
> 	entry->pagelist =  kcalloc(pages, sizeof(*entry->pagelist), GFP_KERNEL);
>
>> -	entry->busaddr = kmalloc(pages * sizeof(*entry->busaddr), GFP_KERNEL);
>> +	entry->busaddr = kzalloc(pages * sizeof(*entry->busaddr), GFP_KERNEL);
>
> here too.
>
Is there any significant benefit of using kcalloc here?


Thanks,
Rakib
>

Re: [PATCH] drivers: Use kzalloc instead of 'kmalloc+memset', where possible.

[Joe Perches]

On Tue, 2011-05-24 at 22:59 +0600, Rakib Mullick wrote:
> On 5/23/11, Joe Perches <joe@perches.com> wrote:
> > On Mon, 2011-05-23 at 23:40 +0600, Rakib Mullick wrote:
> >> Following patch removes the uses of 'kmalloc+memset' from various
> >> drivers subsystems, which is replaced by kzalloc. kzalloc take care of
> >> setting allocated memory with null, so it helps to get rid from using
> >> memset.
> >> diff --git a/drivers/gpu/drm/drm_scatter.c b/drivers/gpu/drm/drm_scatter.c
> > []
> >> -	entry->pagelist = kmalloc(pages * sizeof(*entry->pagelist), GFP_KERNEL);
> >> +	entry->pagelist = kzalloc(pages * sizeof(*entry->pagelist), GFP_KERNEL);
> > Perhaps it's better to use:
> > 	entry->pagelist =  kcalloc(pages, sizeof(*entry->pagelist), GFP_KERNEL);
> >> -	entry->busaddr = kmalloc(pages * sizeof(*entry->busaddr), GFP_KERNEL);
> >> +	entry->busaddr = kzalloc(pages * sizeof(*entry->busaddr), GFP_KERNEL);
> > here too.
> Is there any significant benefit of using kcalloc here?

Overflow and tradition.

static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
{
	if (size != 0 && n > ULONG_MAX / size)
		return NULL;
	return __kmalloc(n * size, flags | __GFP_ZERO);
}

Re: [PATCH] drivers: Use kzalloc instead of 'kmalloc+memset', where possible.

[Rakib Mullick]

[-- Attachment #1.1: Type: text/plain, Size: 1893 bytes --]

On Tue, May 24, 2011 at 11:09 PM, Joe Perches <joe@perches.com> wrote:

> On Tue, 2011-05-24 at 22:59 +0600, Rakib Mullick wrote:
> > On 5/23/11, Joe Perches <joe@perches.com> wrote:
> > > On Mon, 2011-05-23 at 23:40 +0600, Rakib Mullick wrote:
> > >> Following patch removes the uses of 'kmalloc+memset' from various
> > >> drivers subsystems, which is replaced by kzalloc. kzalloc take care of
> > >> setting allocated memory with null, so it helps to get rid from using
> > >> memset.
> > >> diff --git a/drivers/gpu/drm/drm_scatter.c
> b/drivers/gpu/drm/drm_scatter.c
> > > []
> > >> -  entry->pagelist = kmalloc(pages * sizeof(*entry->pagelist),
> GFP_KERNEL);
> > >> +  entry->pagelist = kzalloc(pages * sizeof(*entry->pagelist),
> GFP_KERNEL);
> > > Perhaps it's better to use:
> > >     entry->pagelist =  kcalloc(pages, sizeof(*entry->pagelist),
> GFP_KERNEL);
> > >> -  entry->busaddr = kmalloc(pages * sizeof(*entry->busaddr),
> GFP_KERNEL);
> > >> +  entry->busaddr = kzalloc(pages * sizeof(*entry->busaddr),
> GFP_KERNEL);
> > > here too.
> > Is there any significant benefit of using kcalloc here?
>
> Overflow and tradition.
>
> static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
> {
>        if (size != 0 && n > ULONG_MAX / size)
>                return NULL;
>        return __kmalloc(n * size, flags | __GFP_ZERO);
> }
>
> It's been used for allocating memory for an array. Maybe, using kcalloc in
entry->pagelist could be useful. But, not that much sure though. There's no
problem with current implementation.

This patch touches few drivers subsystems, they are added to the CC list.

Thanks,
Rakib

>
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