Re: [PATCH 12/16] asm-generic: siginfo: remove obsolete #ifdefs

From: Arnd Bergmann <arnd@arndb.de>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-arch <linux-arch@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 12/16] asm-generic: siginfo: remove obsolete #ifdefs
Date: Thu, 15 Mar 2018 13:50:36 +0100	[thread overview]
Message-ID: <CAK8P3a2ii0aQ6sSB_B_KeMWw51Y8mbX0eL6EPj5fQ8b8bJqmUQ@mail.gmail.com> (raw)
In-Reply-To: <87o9jpbmcy.fsf@xmission.com>

On Thu, Mar 15, 2018 at 12:37 PM, Eric W. Biederman
<ebiederm@xmission.com> wrote:
>> On Thu, Mar 15, 2018 at 11:06 AM, Eric W. Biederman

>> That seems reasonable. If you send me a patch with a proper
>> changelog (I don't think I could explain this well enough), I'll
>> add it to the series.
>
> I just realized you can also remove the #ifdefs for BUS_MCEERR_AR,
> BUS_MCEERR_AO, and SEGV_BNDERR.  As those si_codes are now always
> defined.  That description I expect you can handle.

My existing patch already does this, and I've added a note to the changelog
as well now.

> For a description of the above change how does this sound?
>
> Unlike system call numbers the assignment of si_codes has never had a
> reason to be made per architecture.  Some architectures have had unique
> conditions to report and reporting those conditions needed new si_codes.
> Nothing has ever needed si_codes to have different values on different
> architectures.  The si_code space is vast so even with defining all
> si_codes on all architectures there is no danger in running out of
> si_code values.
>
> The history of the si_codes BUS_MCEERR_AR, BUS_MCEER_AO, SEGV_BNDERR,
> and SEGV_PKUERR show that a need of one architecture frequently becomes
> a need of another architecture which makes sharing si_codes between
> architectures a positive benefit and something to be encouraged.
>
> Where there are no conflicts with the historical ia64 arch specific
> si_codes and any other si_codes make them generic si_codes.  We might
> need them on another architecture someday.
>
> This leaves only the good example of arch generic si_codes in the kernel
> for future architectures and architecture enhancments to follow.
> Without bad examples to follow it should be easy to avoid the mistakes
> of the past.

Ok, done. I've listed you as 'Suggested-by' for that patch. Since the
changelog is way more work than the actual change, I would have
made you the author of that patch, but I don't have a Signed-off-by
from you for it.

      Arnd