| Date | Sat, 12 Mar 2022 23:54:09 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 16/19] context_tracking: Convert state to atomic_t |
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On Wed, Mar 02, 2022 at 04:48:07PM +0100, Frederic Weisbecker wrote: > +static __always_inline int __ct_state(void) > +{ > + return atomic_read(this_cpu_ptr(&context_tracking.state)); > +}
One arguably horrible thing to do would be to write it like:
return __this_cpu_read(context_tracking.state.counter);
IIRC that will actually DTRT since atomic_read() is basically defined to be READ_ONCE() and this_cpu_read() implies the same.
Only PowerPC and s390 implement arch_atomic_read() in asm, but I don't think they have a particularly good reason to. The only other weird case is Alpha, where READ_ONCE() implies smp_mb() because Alpha. I'm not sure we care about that case, hmm?
The same can be done for ct_dynticks(), which is basically the same function with a different mask.
As mentioned elsewhere, ct_state() appears unused at the end of the ride.
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