linux-kernel - Re: [PATCH 08/15] powerpc/powernv: implement opal_put_chars

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87zi1bbvnl.fsf@concordia.ellerman.id.au>
Date:   Mon, 07 May 2018 20:35:42 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Nicholas Piggin <npiggin@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Jiri Slaby <jslaby@...e.com>
Subject: Re: [PATCH 08/15] powerpc/powernv: implement opal_put_chars_atomic

Nicholas Piggin <npiggin@...il.com> writes:

> On Tue, 01 May 2018 19:48:58 +1000
> Benjamin Herrenschmidt <benh@...nel.crashing.org> wrote:
>
>> On Tue, 2018-05-01 at 00:55 +1000, Nicholas Piggin wrote:
>> > The RAW console does not need writes to be atomic, so relax
>> > opal_put_chars to be able to do partial writes, and implement an
>> > _atomic variant which does not take a spinlock. This API is used
>> > in xmon, so the less locking that is used, the better chance there
>> > is that a crash can be debugged.  
>> 
>> Same comment I already had :-) "atomic" in Linux tends to mean
>> something else (ie, atomic context), so I'd rather have something
>> like opal_put_chars_sync() or such...
>
> Oh yeah, I didn't ignore you, just... I thought atomic was okay.
> atomic *also* tends to mean happens atomically. I think the in
> atomic context meaning actually tends to be inatomic.
>
> Sync I actually thought could be more easily confused with
> synchronous vs asynchronous here.

I think we probably want opal_put_chars() to stay as it is.

And then add a variant for the call (just xmon?) that want lock free
behaviour.

opal_put_chars_unlocked() or something?

cheers