linux-kernel - Re: [PATCH 1/6] ARM: fix memset size error

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Message-ID: <Pine.LNX.4.64.0711042302580.31550@localhost.localdomain>
Date:	Sun, 4 Nov 2007 23:06:32 -0500 (EST)
From:	"Robert P. J. Day" <rpjday@...shcourse.ca>
To:	Li Zefan <lizf@...fujitsu.com>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, buytenh@...tstofly.org
Subject: Re: [PATCH 1/6] ARM: fix memset size error

On Mon, 5 Nov 2007, Li Zefan wrote:

> The size passing to memset is wrong. And here we can replace
> kmalloc with kzalloc.
>
> Signed-off-by Li Zefan <lizf@...fujitsu.com>
>
> ---
>  arch/arm/common/uengine.c |    6 ++----
>  1 files changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/common/uengine.c b/arch/arm/common/uengine.c
> index 95c8508..117cab3 100644
> --- a/arch/arm/common/uengine.c
> +++ b/arch/arm/common/uengine.c
> @@ -374,8 +374,8 @@ static int set_initial_registers(int uengine, struct ixp2000_uengine_code *c)
>  	u8 *ucode;
>  	int i;
>
> -	gpr_a = kmalloc(128 * sizeof(u32), GFP_KERNEL);
> -	gpr_b = kmalloc(128 * sizeof(u32), GFP_KERNEL);
> +	gpr_a = kzalloc(128 * sizeof(u32), GFP_KERNEL);
> +	gpr_b = kzalloc(128 * sizeof(u32), GFP_KERNEL);
>  	ucode = kmalloc(513 * 5, GFP_KERNEL);
>  	if (gpr_a == NULL || gpr_b == NULL || ucode == NULL) {
>  		kfree(ucode);
> @@ -388,8 +388,6 @@ static int set_initial_registers(int uengine, struct ixp2000_uengine_code *c)
>  	if (c->uengine_parameters & IXP2000_UENGINE_4_CONTEXTS)
>  		per_ctx_regs = 32;
>
> -	memset(gpr_a, 0, sizeof(gpr_a));
> -	memset(gpr_b, 0, sizeof(gpr_b));
>  	for (i = 0; i < 256; i++) {
>  		struct ixp2000_reg_value *r = c->initial_reg_values + i;
>  		u32 *bank;
>
  it's unlikely that patch will cause any trouble whatsoever, but
notice that it *is* changing the underlying logic.  those original
memsets should probably have been written initially as
"sizeof(*gpr_a)" so they would previously have zeroed only memory the
        ^
size of a pointer, no?

  now, i'm guessing the logic is correct but i figured it's worth
noting what the code *used* to do.  unless i'm misreading something
horribly.



rday
-- 
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://crashcourse.ca
========================================================================
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