[PATCH] mm/vmalloc.c: fix sparse warning

[PATCH] mm/vmalloc.c: fix sparse warning

[H Hartley Sweeten]

Fix sparse warning in mm/vmalloc.c.

  warning: symbol 'tmp' shadows an earlier one

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>

---

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index fab1987..4959a30 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -292,13 +292,13 @@ static void __insert_vmap_area(struct vmap_area
*va)
 	struct rb_node *tmp;
 
 	while (*p) {
-		struct vmap_area *tmp;
+		struct vmap_area *tmp_va;
 
 		parent = *p;
-		tmp = rb_entry(parent, struct vmap_area, rb_node);
-		if (va->va_start < tmp->va_end)
+		tmp_va = rb_entry(parent, struct vmap_area, rb_node);
+		if (va->va_start < tmp_va->va_end)
 			p = &(*p)->rb_left;
-		else if (va->va_end > tmp->va_start)
+		else if (va->va_end > tmp_va->va_start)
 			p = &(*p)->rb_right;
 		else
 			BUG(); 

Re: [PATCH] mm/vmalloc.c: fix sparse warning

[Andrew Morton]

On Fri, 17 Apr 2009 20:55:06 -0400
"H Hartley Sweeten" <hartleys@visionengravers.com> wrote:

> Fix sparse warning in mm/vmalloc.c.
> 
>   warning: symbol 'tmp' shadows an earlier one
> 
> Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
> 
> ---
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index fab1987..4959a30 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -292,13 +292,13 @@ static void __insert_vmap_area(struct vmap_area
> *va)
>  	struct rb_node *tmp;
>  
>  	while (*p) {
> -		struct vmap_area *tmp;
> +		struct vmap_area *tmp_va;
>  
>  		parent = *p;
> -		tmp = rb_entry(parent, struct vmap_area, rb_node);
> -		if (va->va_start < tmp->va_end)
> +		tmp_va = rb_entry(parent, struct vmap_area, rb_node);
> +		if (va->va_start < tmp_va->va_end)
>  			p = &(*p)->rb_left;
> -		else if (va->va_end > tmp->va_start)
> +		else if (va->va_end > tmp_va->va_start)
>  			p = &(*p)->rb_right;
>  		else
>  			BUG(); 

It would be sufficient to simply delete the inner definition of `tmp'.

Use of a variable called "tmp" is often bad - it's almost always a
result of plain old laziness and the code can be improved by using a
more meaningful identifier.

But in this case the code is sufficiently short and simple that I guess
we can live with "tmp".

Re: [PATCH] mm/vmalloc.c: fix sparse warning

[Al Viro]

On Thu, Apr 23, 2009 at 01:23:58PM -0700, Andrew Morton wrote:
> On Fri, 17 Apr 2009 20:55:06 -0400
> "H Hartley Sweeten" <hartleys@visionengravers.com> wrote:
> 
> > Fix sparse warning in mm/vmalloc.c.
> > 
> >   warning: symbol 'tmp' shadows an earlier one

Folks, could we please add to appropriate documentation (SubmittingPatches,
perhaps) a bit about using descriptive subjects?

In general, "$TOOL warning in $FILE" says nothing useful.  In this case
"Get rid of shadowed variable in mm/vmalloc.c:<function>" would be far
more useful, with "found by sparse" _maybe_ showing up in the commit
message more or less as a footnote.  Or even "shadowed variable in
mm/vmalloc.c:<function>".

Re: [PATCH] mm/vmalloc.c: fix sparse warning

[Andrew Morton]

On Thu, 23 Apr 2009 21:35:57 +0100
Al Viro <viro@ZenIV.linux.org.uk> wrote:

> On Thu, Apr 23, 2009 at 01:23:58PM -0700, Andrew Morton wrote:
> > On Fri, 17 Apr 2009 20:55:06 -0400
> > "H Hartley Sweeten" <hartleys@visionengravers.com> wrote:
> > 
> > > Fix sparse warning in mm/vmalloc.c.
> > > 
> > >   warning: symbol 'tmp' shadows an earlier one
> 
> Folks, could we please add to appropriate documentation (SubmittingPatches,
> perhaps) a bit about using descriptive subjects?

If everyone did that, my typing skillz would deteriorate.

> In general, "$TOOL warning in $FILE" says nothing useful.  In this case
> "Get rid of shadowed variable in mm/vmalloc.c:<function>" would be far
> more useful, with "found by sparse" _maybe_ showing up in the commit
> message more or less as a footnote.  Or even "shadowed variable in
> mm/vmalloc.c:<function>".

yup.