On Mon, Sep 23, 2024 at 09:28:31AM -0700, Linus Torvalds wrote: > On Wed, 18 Sept 2024 at 08:22, Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > On Wed, 18 Sept 2024 at 13:15, Christoph Lameter (Ampere) <cl@xxxxxxxxxx> wrote: > > > > > > Other arches do not have acquire / release and will create additional > > > barriers in the fallback implementation of smp_load_acquire. So it needs > > > to be an arch config option. > > > > Actually, I looked at a few cases, and it doesn't really seem to be true. > > Bah. I ended up just committing the minimal version of this all. I > gave Christoph credit for the commit, because I stole his commit > message, and he did most of the work, I just ended up going "simplify, > simplify, simplify". > > I doubt anybody will notice, and smp_load_acquire() is the future. Any > architecture that does badly on it just doesn't matter (and, as > mentioned, I don't think they even exist - "smp_rmb()" is generally at > least as expensive). Do we want to do the complementing patch and make write_seqcount_end() use smp_store_release() ? I think at least ARM (the 32bit thing) has wmb but uses mb for store_release. But I also think I don't really care about that.
