[PATCH] Fix tst-pkey.c pkey_alloc return checks and manual

[Gabriel F. T. Gomes]

Hi, Lucas,

Thanks for doing this.  This failure has haunted my Debian systems for
a long time.

The patch looks good to me.  I only have a cosmetic suggestion.

Reviewed-by: Gabriel F. T. Gomes <gabriel@inconstante.net.br>

On Thu, 16 Jan 2020, Lucas A. M. Magalhaes wrote:

> This test was failing in some powerpc systems as it was not checking
> for ENOSPC return.
> 
> As said on the Linux man-pages and can be observed by the implementation
> at mm/mprotect.c in the Linux Kernel source.  The syscall pkey_alloc can
> return EINVAL or ENOSPC.  ENOSPC will indicate either that all keys are
> in use or that the kernel does not support pkeys.

Good commit message.

> --- a/manual/memory.texi
> +++ b/manual/memory.texi
> @@ -3288,6 +3288,10 @@ in which memory protection keys are disabled.
>  
>  @item ENOSPC
>  All available protection keys already have been allocated.
> +
> +The system does not implement memory protection keys or runs in a mode
> +in which memory protection keys are disabled.
> +

I think the wording at the commit message is better, because it makes
it clear that it's one situation or the other, so maybe:

  Either all available protection keys already have been allocated, or
  the system does not implement memory protection keys, or runs in a
  mode in which memory protection keys are disabled.