Re: [PATCH] cpumask: Omit terminating null byte in cpumap_print_{list,bitmask}_to_buf

[Barry Song]

On Thu, Sep 30, 2021 at 11:31 PM Antti Kervinen
<antti.kervinen@xxxxxxxxx> wrote:
>
>
> An original function, bitmap_print_to_pagebuf() in lib/bitmap.c,
> returns the number of printed characters, excluding terminating null.
>

a patch has been in
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c86a2d9058c5a4a05d20ef89e699b7a6b2c89da6

I guess it is on the way to linus' tree.

> Commit 1fae5629, a cause of this regression, introduced new functions
> to lib/bitmap.c:
>
> - bitmap_print_to_buf()
>   (return value doc missing)
>
> - bitmap_print_bitmask_to_buf()
>   (return value doc not explicit about terminating null, but
>   can be considered misleading)
>
> - bitmap_print_list_to_buf()
>   (the same as above)
>
> Unlike the original function, the return value of new functions
> include the terminating null.
>
> As this behavior is clearly opposite to the original function, and
> functions that print to buffers in general, I would suggest fixing
> this problem by alignign these new functions with the original one:
> excluding the terminating null. And documenting this behavior
> unambiguously.
>
> The suggested change to cpumask_print_{bitmask,list}_to_buf()
> functions decrements possible errors (like -ENOMEM) returned by
> bitmap_print_to_buf(). This must not happen.

Thanks
barry