From mboxrd@z Thu Jan  1 00:00:00 1970
From: peterz@infradead.org (Peter Zijlstra)
Date: Mon, 4 Jan 2016 14:36:58 +0100
Subject: [PATCH v2 17/32] arm: define __smp_xxx
In-Reply-To: <20160103110158-mutt-send-email-mst@redhat.com>
References: <1451572003-2440-1-git-send-email-mst@redhat.com>
 <1451572003-2440-18-git-send-email-mst@redhat.com>
 <20160102112438.GU8644@n2100.arm.linux.org.uk>
 <20160103110158-mutt-send-email-mst@redhat.com>
Message-ID: <20160104133658.GY6344@twins.programming.kicks-ass.net>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Sun, Jan 03, 2016 at 11:12:44AM +0200, Michael S. Tsirkin wrote:
> On Sat, Jan 02, 2016 at 11:24:38AM +0000, Russell King - ARM Linux wrote:

> > My only concern is that it gives people an additional handle onto a
> > "new" set of barriers - just because they're prefixed with __*
> > unfortunately doesn't stop anyone from using it (been there with
> > other arch stuff before.)
> > 
> > I wonder whether we should consider making the smp memory barriers
> > inline functions, so these __smp_xxx() variants can be undef'd
> > afterwards, thereby preventing drivers getting their hands on these
> > new macros?
> 
> That'd be tricky to do cleanly since asm-generic depends on
> ifndef to add generic variants where needed.
> 
> But it would be possible to add a checkpatch test for this.

Wasn't the whole purpose of these things for 'drivers' (namely
virtio/xen hypervisor interaction) to use these?

And I suppose most of virtio would actually be modules, so you cannot do
what I did with preempt_enable_no_resched() either.

But yes, it would be good to limit the use of these things.