[PATCH] powerpc/mm: match variable types to API

[PATCH] powerpc/mm: match variable types to API

[Paul Gortmaker]

From: Joe MacDonald <joe.macdonald@windriver.com>

sys_subpage_prot() takes an unsigned long for 'addr' then does some stuff
with it and the result is stored in a signed int, i, which is eventually
used as the size parameter in a copy_from_user call.  Update 'i' to be an
unsigned long as well and since 'nw' is used in a size_t context which,
depending on whether this is 32- or 64-bit may be unsigned int or unsigned
long, switch that to a size_t and always be right.

Finally, since we're in the neighbourhood, make the same changes to
subpage_prot_clear().

Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Joe MacDonald <joe.macdonald@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 arch/powerpc/mm/subpage-prot.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c
index e4f8f1f..7c415dd 100644
--- a/arch/powerpc/mm/subpage-prot.c
+++ b/arch/powerpc/mm/subpage-prot.c
@@ -95,7 +95,8 @@ static void subpage_prot_clear(unsigned long addr, unsigned long len)
 	struct mm_struct *mm = current->mm;
 	struct subpage_prot_table *spt = &mm->context.spt;
 	u32 **spm, *spp;
-	int i, nw;
+	unsigned long i;
+	size_t nw;
 	unsigned long next, limit;
 
 	down_write(&mm->mmap_sem);
@@ -144,7 +145,8 @@ long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
 	struct mm_struct *mm = current->mm;
 	struct subpage_prot_table *spt = &mm->context.spt;
 	u32 **spm, *spp;
-	int i, nw;
+	unsigned long i;
+	size_t nw;
 	unsigned long next, limit;
 	int err;
 
-- 
1.7.11.1

Re: [PATCH] powerpc/mm: match variable types to API

[Paul Mackerras]

On Tue, Aug 21, 2012 at 02:22:28PM -0400, Paul Gortmaker wrote:
> From: Joe MacDonald <joe.macdonald@windriver.com>
> 
> sys_subpage_prot() takes an unsigned long for 'addr' then does some stuff
> with it and the result is stored in a signed int, i, which is eventually
> used as the size parameter in a copy_from_user call.  Update 'i' to be an
> unsigned long as well and since 'nw' is used in a size_t context which,
> depending on whether this is 32- or 64-bit may be unsigned int or unsigned
> long, switch that to a size_t and always be right.
> 
> Finally, since we're in the neighbourhood, make the same changes to
> subpage_prot_clear().
> 
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Joe MacDonald <joe.macdonald@windriver.com>
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

This change won't hurt; in fact it won't make any difference since (a)
this code is only ever used on 64-bit and (b) i and nw are restricted
to the range 0 .. PTRS_PER_PTE - 1, but I agree the code is slightly
cleaner this way.

Acked-by: Paul Mackerras <paulus@samba.org>