[PATCH v2] arm64: tlbflush: Don't broadcast if mm was only active on local cpu

[Will Deacon]

On Sun, Jun 14, 2026 at 12:04:44PM +0100, Will Deacon wrote:
> Can you simplify the 'if' condition here?
> 
> 	if (active == ACTIVE_CPU_NONE) {
> 		if (!try_cmpxchg_relaxed(...))
> 			WRITE_ONCE(...);
> 
> 		dsb(ishst);
> 	}
> 
> (as an aside, maybe we should implement arch_try_cmpxchg{,_relaxed} so
>  we could drop the READ_ONCE() here as well?)

Mulling this over a little more, we probably can't drop the READ_ONCE()
even if we optimised our try_cmpxchg() implementation, as it would
prevent us from eliding the DSB on the fast path.

The rest of my comments (including the refactoring above) stand, however.

Will