On Mon, Mar 27, 2017 at 10:24:40AM +0200, Peter Zijlstra wrote: > On Mon, Mar 27, 2017 at 09:40:46AM +0200, Nicholas Mc Guire wrote: > > > Found by coccinelle: bugon.cocci > > ./kernel/sched/core.c:5913:2-5: WARNING: Use BUG_ON instead of if condition > > followed by BUG. > > Right, so I disagree with that here. > > > @@ -5909,8 +5909,8 @@ void __init sched_init_smp(void) > > mutex_unlock(&sched_domains_mutex); > > > > /* Move init over to a non-isolated CPU */ > > - if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) > > - BUG(); > > + BUG_ON(set_cpus_allowed_ptr(current, non_isolated_cpus) < 0); > > + > > sched_init_granularity(); > > free_cpumask_var(non_isolated_cpus); > > If the condition were without side effects, that pattern would hold, but > here the function call set_cpus_allowed_ptr() is very much not a pure > function, so wrapping it in a BUG_ON() just fels wrong.
Got it - just looked throug core.c and there it seems only side-effect free test-functions are wrapped in BUG_ON() so this change is inconsistent. Other subsystems seem not to follow that logic - might be worth a note somewhere below Documentation/. thx! hofrat
