Re: [PATCH] drivers: Conversions from kmalloc+memset to k(z|c)alloc.

Paulo Marques
2006-07-19T13:53:36Z

Panagiotis Issaris wrote:
> [...]
> --- a/drivers/char/consolemap.c
> +++ b/drivers/char/consolemap.c
> @@ -192,11 +192,9 @@ static void set_inverse_transl(struct vc
> q = p->inverse_translations[i];
>
> if (!q) {
> - q = p->inverse_translations[i] = (unsigned char *)
> - kmalloc(MAX_GLYPH, GFP_KERNEL);
> + q = p->inverse_translations[i] = kzalloc(MAX_GLYPH, GFP_KERNEL);
> if (!q) return;
> }
> - memset(q, 0, MAX_GLYPH);

This changes semantics here. Before, the data pointed by q was always
cleared whether it was malloc'ed or not. Now it is only cleared if it is
malloc'ed. I haven't checked the code to find out if this is ok, though.

> @@ -2704,8 +2702,7 @@ static void cardmap_set(struct cardmap *
> if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
> do {
> /* need a new top level */
> - struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
> - memset(np, 0, sizeof(*np));
> + struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
> np->ptr[0] = p;
> if (p != NULL) {
> np->shift = p->shift + CARDMAP_ORDER;
> @@ -2719,8 +2716,7 @@ static void cardmap_set(struct cardmap *
> while (p->shift > 0) {
> i = (nr >> p->shift) & CARDMAP_MASK;
> if (p->ptr[i] == NULL) {
> - struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
> - memset(np, 0, sizeof(*np));
> + struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
> np->shift = p->shift - CARDMAP_ORDER;
> np->parent = p;
> p->ptr[i] = np;

This is not your fault, but this code is using the return value from
kmalloc (or kzalloc, now) without checking for NULL.

> diff --git a/drivers/scsi/megaraid.c b/drivers/scsi/megaraid.c
> index 76edbb6..71d4743 100644
> --- a/drivers/scsi/megaraid.c
> +++ b/drivers/scsi/megaraid.c
> @@ -4487,8 +4487,7 @@ mega_internal_command(adapter_t *adapter
> scmd = &adapter->int_scmd;
> memset(scmd, 0, sizeof(Scsi_Cmnd));
>
> - sdev = kmalloc(sizeof(struct scsi_device), GFP_KERNEL);
> - memset(sdev, 0, sizeof(struct scsi_device));
> + sdev = kzalloc(sizeof(struct scsi_device), GFP_KERNEL);
> scmd->device = sdev;
>
> scmd->device->host = adapter->host;

Same here.

> --- a/drivers/video/offb.c
> +++ b/drivers/video/offb.c
> @@ -376,13 +376,12 @@ static void __init offb_init_fb(const ch
>
> size = sizeof(struct fb_info) + sizeof(u32) * 17;
>
> - info = kmalloc(size, GFP_ATOMIC);
> + info = kzalloc(size, GFP_ATOMIC);
>
> if (info == 0) {

Again, not your fault, but "info == 0"? If you're doing a new version of
the patch, please change this to NULL or !info, so that we don't confuse
human readers :)

--
Paulo Marques - www.grupopie.com

"I can picture in my mind a world without war, a world
without hate. And I can picture us attacking that world,
because they'd never expect it."