On Thu, Jan 16, 2025 at 12:02:34PM -0800, Paul E. McKenney wrote: > +The special cases where it makes sense do obtain a per-CPU pointer in s/do/to/ > +preemptible code are addressed by raw_cpu_ptr(), but please note that such s/please note that // > +use cases need to handle cases where two different CPUs are accessing > +the same per cpu variable, which might well be that of a third CPU. > +These use cases are typically performance optimizations. For example, > +SRCU implements a pair of counters as a pair of per-CPU variables, > +and rcu_read_lock_nmisafe() uses raw_cpu_ptr() to get a pointer to some > +CPU's counter, and uses atomic_inc_long() to handle migration between > +the raw_cpu_ptr() and the atomic_inc_long().
