Re: [PATCH] backlight: lp855x: fix unintialized function return

[Daniel Thompson]

On Fri, Aug 11, 2023 at 03:15:53PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann 
>
> The function now returns an error code in some cases, but fails to initialize
> it in others:
>
> drivers/video/backlight/lp855x_bl.c:252:11: error: variable 'ret' is used 
> uninitialized whenever 'if' condition is false 
> [-Werror,-Wsometimes-uninitialized]
> else if (lp->mode == REGISTER_BASED)
>  ^~
> drivers/video/backlight/lp855x_bl.c:256:9: note: uninitialized use occurs here
> return ret;
>^~~
> drivers/video/backlight/lp855x_bl.c:252:7: note: remove the 'if' if its 
> condition is always true
> else if (lp->mode == REGISTER_BASED)
>  ^~~
>
> Since this case should not actually happen, return the -EINVAL code.
>
> Fixes: 5145531be5fba ("backlight: lp855x: Catch errors when changing 
> brightness")
> Signed-off-by: Arnd Bergmann 

I think we already received a patch for this:
https://lore.kernel.org/lkml/20230809163825.ga5...@aspen.lan/T/


Daniel.

[PATCH] backlight: lp855x: fix unintialized function return

[Arnd Bergmann]

From: Arnd Bergmann 

The function now returns an error code in some cases, but fails to initialize
it in others:

drivers/video/backlight/lp855x_bl.c:252:11: error: variable 'ret' is used 
uninitialized whenever 'if' condition is false 
[-Werror,-Wsometimes-uninitialized]
else if (lp->mode == REGISTER_BASED)
 ^~
drivers/video/backlight/lp855x_bl.c:256:9: note: uninitialized use occurs here
return ret;
   ^~~
drivers/video/backlight/lp855x_bl.c:252:7: note: remove the 'if' if its 
condition is always true
else if (lp->mode == REGISTER_BASED)
 ^~~

Since this case should not actually happen, return the -EINVAL code.

Fixes: 5145531be5fba ("backlight: lp855x: Catch errors when changing 
brightness")
Signed-off-by: Arnd Bergmann 
---
 drivers/video/backlight/lp855x_bl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/backlight/lp855x_bl.c 
b/drivers/video/backlight/lp855x_bl.c
index 61a7f45bfad84..ea4fa69e49a70 100644
--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -252,6 +252,8 @@ static int lp855x_bl_update_status(struct backlight_device 
*bl)
else if (lp->mode == REGISTER_BASED)
ret = lp855x_write_byte(lp, lp->cfg->reg_brightness,
(u8)brightness);
+   else
+   ret = -EINVAL;
 
return ret;
 }
-- 
2.39.2