Re: [PATCH] drm/vblank: Fixup and document timestamp update/read barriers

On Thu, Apr 16, 2015 at 05:00:02AM -0400, Peter Hurley wrote:

On 04/16/2015 02:39 AM, Mario Kleiner wrote:

...

I think i'm still not getting something about why the compiler would be allowed to reorder in this way in absence of the additional smp_rmb? Or is that barrier required for other archs which are less strongly ordered?

Apologies for the confusion; I missed that it was data-dependent load.

Oh right missed that too. Well, alpha can do anything, we'd need at least a read_barrier_depends(); here. Tbh not sure that's worth it since with the plain smp_rmb() we match the seqlock code exactly. -Daniel