Re: [PATCH v1] powerpc: Fix off-by-one bug

[Ritesh Harjani (IBM) <ritesh.list@gmail.com>]

Alejandro Colomar <alx@kernel.org> writes:

> From the surrounding similar calls, the intention seems obvious: this
> seems intended to check for a prefix.
>

Could be, however the existing code is not functionally wrong either.

I agree it would have been nicer if all three were consistent. However,
x86 handles the same parameters with exact matches, so if anything "auto"
is the one doing the right thing here :)

But making "on"/"off" exact matches on powerpc now could change
behaviour for someone passing e.g. "offline" today, so I'd rather leave
those alone too.

> However, I do not understand this code, so take my reading with a grain
> of salt.
>
> Fixes: a048a07d7f453 ("powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit")

IMHO, I don't think this patch fixes anything functional. So, I don't
think it will be correct to call this as: "Fix off-by-one bug" or 
add fixes tag to it.
And so, I would suggest, we leave leave today's code as is, based on the
previous reasoning.

> Signed-off-by: Alejandro Colomar <alx@kernel.org>
> ---
>
> I found this while looking into replacing this code with calls to
> strprefix().
>

For your conversion, I think, we should keep today's behaviour as is.
Maybe streq() for "auto" and strprefix() for "on" and "off", which means
there is is nothing to change or fix.

-ritesh