[PATCH] kconfig: Fix compiler warning

[PATCH] kconfig: Fix compiler warning

[Eddie Kovsky]

Fixes gcc warning when building linux-next:

In file included from scripts/kconfig/zconf.tab.c:2537:0:
scripts/kconfig/menu.c: In function ‘get_symbol_str’:
scripts/kconfig/menu.c:590:18: warning: ‘jump’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     jump->offset = strlen(r->s);
                  ^
scripts/kconfig/menu.c:551:19: note: ‘jump’ was declared here
  struct jump_key *jump;
                   ^
  HOSTLD  scripts/kconfig/conf

Moved the initialization of struct jump_key *jump outside the first
'if' branch so it can be available throughout the function.

Also uses the preferred pointer syntax for passing the size of a struct.

Tested on next-20141119.

Signed-off-by: Eddie Kovsky <ewk@edkovsky.org>
---
 scripts/kconfig/menu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index a26cc5d2a9b0..a728d23949e7 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -559,8 +559,8 @@ static void get_prompt_str(struct gstr *r, struct property *prop,
 		if (location == NULL && accessible)
 			location = menu;
 	}
+	jump = xmalloc(sizeof(*jump));
 	if (head && location) {
-		jump = xmalloc(sizeof(struct jump_key));
 
 		if (menu_is_visible(prop->menu)) {
 			/*
-- 
2.1.0

Re: [PATCH] kconfig: Fix compiler warning

[Michal Marek]

On 2014-11-20 06:44, Eddie Kovsky wrote:
> diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
> index a26cc5d2a9b0..a728d23949e7 100644
> --- a/scripts/kconfig/menu.c
> +++ b/scripts/kconfig/menu.c
> @@ -559,8 +559,8 @@ static void get_prompt_str(struct gstr *r, struct property *prop,
>  		if (location == NULL && accessible)
>  			location = menu;
>  	}
> +	jump = xmalloc(sizeof(*jump));
>  	if (head && location) {
> -		jump = xmalloc(sizeof(struct jump_key));

This creates a memory leak, because 'jump' is allocated, but not added
to the list, if the following condition is not met.

Michal

[PATCH] kconfig: Fix compiler warning

[Sascha Hauer]

gcc-4.9 is too silly to recognize that *jump cannot be used
uninitialized and issues a warning. Explicitly initialize
*jump to avoid the warning.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 scripts/kconfig/menu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index fd3f018..bea100b 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -525,7 +525,7 @@ static void get_prompt_str(struct gstr *r, struct property *prop,
 {
 	int i, j;
 	struct menu *submenu[8], *menu, *location = NULL;
-	struct jump_key *jump;
+	struct jump_key *jump = NULL;
 
 	str_printf(r, _("Prompt: %s\n"), _(prop->text));
 	menu = prop->menu->parent;
-- 
2.0.0


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Re: [PATCH] kconfig: Fix compiler warning

[Alexander Aring]

Hi Sascha,

I get this warning about 1 month and it makes me crazy and I am unsing
"gcc (GCC) 4.9.0 20140604 (prerelease)".


Why I didn't sent any patches?
Because you say it here it's a compiler bug and the linux world doesn't
fix it this way. Look at [0].

"... since we will still want to catch unitialised use in the future,
should we were to changethe code." - which sounds useful.

They already add a comment to this. I think otherwise they get much
patches because this warning.

When I look into the current mainline code [1]. Then this is currently
not fixed in any way (comment or setting to NULL

- Alex

[0] http://www.spinics.net/lists/linux-kbuild/msg08898.html
[1] https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/scripts/kconfig/menu.c?id=refs/tags/next-20140626

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Re: [PATCH] kconfig: Fix compiler warning

[Uwe Kleine-König]

On Thu, Jun 26, 2014 at 11:02:18AM +0200, Alexander Aring wrote:
> Hi Sascha,
> 
> I get this warning about 1 month and it makes me crazy and I am unsing
> "gcc (GCC) 4.9.0 20140604 (prerelease)".
> 
> 
> Why I didn't sent any patches?
> Because you say it here it's a compiler bug and the linux world doesn't
> fix it this way. Look at [0].
> 
> "... since we will still want to catch unitialised use in the future,
> should we were to changethe code." - which sounds useful.
> 
> They already add a comment to this. I think otherwise they get much
> patches because this warning.
> 
> When I look into the current mainline code [1]. Then this is currently
> not fixed in any way (comment or setting to NULL
There is also the macro uninitialized_var (in both kernel and barebox)
that could be used here instead of the explicit = NULL.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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