[RFC] mm/memblock.c: using uninitialized value idx in memblock_add_range()

[RFC] mm/memblock.c: using uninitialized value idx in memblock_add_range()

[gurugio]

From: Gioh Kim <gurugio@hanmail.net>

In memblock_add_range(), idx variable is a local value
but I cannot find initialization of idx value.
I checked idx value on my Qemu emulator. It was zero.
Is there any hidden initialization code?

Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
---
 mm/memblock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index 7b8a5db..23374bc 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -515,7 +515,7 @@ int __init_memblock memblock_add_range(struct memblock_type *type,
 	bool insert = false;
 	phys_addr_t obase = base;
 	phys_addr_t end = base + memblock_cap_size(base, &size);
-	int idx, nr_new;
+	int idx = 0, nr_new;
 	struct memblock_region *rgn;
 
 	if (!size)
-- 
2.7.4

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Re: [RFC] mm/memblock.c: using uninitialized value idx in memblock_add_range()

[Michal Hocko]

On Sat 09-09-17 00:15:33, gurugio@gmail.com wrote:
> From: Gioh Kim <gurugio@hanmail.net>
> 
> In memblock_add_range(), idx variable is a local value
> but I cannot find initialization of idx value.
> I checked idx value on my Qemu emulator. It was zero.
> Is there any hidden initialization code?

Yes for_each_memblock_type. Ugly as hell! Something to clean up I guess.
Just make the index explicit argument of the macro.

> 
> Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
> ---
>  mm/memblock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 7b8a5db..23374bc 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -515,7 +515,7 @@ int __init_memblock memblock_add_range(struct memblock_type *type,
>  	bool insert = false;
>  	phys_addr_t obase = base;
>  	phys_addr_t end = base + memblock_cap_size(base, &size);
> -	int idx, nr_new;
> +	int idx = 0, nr_new;
>  	struct memblock_region *rgn;
>  
>  	if (!size)
> -- 
> 2.7.4

-- 
Michal Hocko
SUSE Labs

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