Messages in this thread | | | Date | Mon, 05 Nov 2007 13:09:51 +0800 | From | Li Zefan <> | Subject | Re: [PATCH 1/6] ARM: fix memset size error |
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Robert P. J. Day wrote: > 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@cn.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. >
In the for loop, some elems of gpr_a and gpr_b will be assigned with a value, but not all elems. So those unassigned elems should be filled with 0.
I think it happens now and then to mistake to regard a pointer as a static array, and I guess this is what sizeof(gpr_a) means.
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