On Thu, May 20, 2021 at 02:54:26AM +0200, Frederic Weisbecker wrote: > On Wed, May 19, 2021 at 11:51:07AM -0700, Paul E. McKenney wrote: > > On Wed, May 19, 2021 at 02:09:30AM +0200, Frederic Weisbecker wrote: > > > rcu_report_dead() is always called locally from the idle path. Passing > > > a CPU number to it suggests otherwise and is rather error-prone as the > > > code inside relies on locality. > > > > > > Robustify the function prototype and refine the name along the way. > > > > > > Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx> > > > > Makes a lot of sense, thank you! > > > > On the function name, here is the list: > > > > int rcutree_prepare_cpu(unsigned int cpu) -- notifier from any CPU. > > void rcu_cpu_starting(unsigned int cpu) -- direct call on incoming CPU. > > int rcutree_online_cpu(unsigned int cpu) -- notifier from any CPU. > > > > int rcutree_offline_cpu(unsigned int cpu) -- notifier from any CPU. > > void rcu_report_dead(unsigned int cpu) -- direct call on outgoing CPU. > > void rcutree_migrate_callbacks(int cpu) -- direct call from surviving CPU. > > int rcutree_dead_cpu(unsigned int cpu) -- notifier from any CPU. > > > > Note that rcu_report_dead() can also be invoked from cpu_die_early() on > > other CPU when onlining a CPU fails. This happens on arm64. Which might > > be an arm64 bug, but unless I am missing something it is a case where > > rcu_report_dead() is called non-locally. > > Hmm, I see it only called with smp_processor_id() from cpu_die_early(). I clearly should have looked at the initialization of that "cpu" local variable. Once again, right you are! > > And the naming is currently a bit random, isn't it? :-/ > > > > Maybe rcutree_*_cpu() if there is a CPU parameter and rcutree_*_self() > > if all calls run on the CPU in question? > > Makes sense. Or rcutree_*_curr_cpu() but it's going to produce long names. Either way, it should be a separate patch. > > I cannot immediately think of a reason to make names reflect whether > > the corresponding functions are directly called or are called via notifier. > > Thoughts? > > No indeed, let's wait for some convention to ever emerge :) Sounds like a long wait, but that works for me! Thanx, Paul
