Re: [PATCH] sbitmap: avoid maybe-uninitialized warning

[Jens Axboe]

On 09/19/2016 06:33 AM, Arnd Bergmann wrote:
> The sbitmap code that has just been turned into a library module
> returns uninitialized data for sbitmap_weight(), as pointed out by
> gcc when building with -Wmaybe-uninitialized:
>
> lib/sbitmap.c: In function 'sbitmap_weight':
> lib/sbitmap.c:179:9: error: 'weight' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> Note that the value is never initialized, we just add data on
> top, so it is wrong regardless of sb->map_nr.
>
> This adds the missing initialization.

Thanks Arnd, Colin sent the same patch and I applied it. Note that:

> Fixes: 88459642cba4 ("blk-mq: abstract tag allocation out into sbitmap library")

that isn't truly correct, that patch is just what moved the code. The 
bug predates that commit.

--
Jens Axboe