Re: [PATCH v2 17/32] arm: define __smp_xxx
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2016-01-04 20:39:32
Also in:
linux-arch, linux-arm-kernel, linux-mips, linux-s390, linux-sh, linux-um, lkml, sparclinux
On Mon, Jan 04, 2016 at 02:54:20PM +0100, Peter Zijlstra wrote:
On Mon, Jan 04, 2016 at 02:36:58PM +0100, Peter Zijlstra wrote:quoted
On Sun, Jan 03, 2016 at 11:12:44AM +0200, Michael S. Tsirkin wrote:quoted
On Sat, Jan 02, 2016 at 11:24:38AM +0000, Russell King - ARM Linux wrote:quoted
quoted
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?Ah, I see, you add virt_*mb() stuff later on for that use case. So, assuming everybody does include asm-generic/barrier.h, you could simply #undef the __smp version at the end of that, once we've generated all the regular primitives from it, no?
Maybe I misunderstand, but I don't think so: ------> #define __smp_xxx FOO #define smp_xxx __smp_xxx #undef __smp_xxx smp_xxx <------ resolves to __smp_xxx, not FOO. That's why I went the checkpatch way. -- MST