Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [PATCH 3/3] sched/nohz: Remove weird error handling from find_new_ilb() | Date | Mon, 09 Oct 2023 17:11:53 +0200 |
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On 06/10/23 13:01, Ingo Molnar wrote: > * Peter Zijlstra <peterz@infradead.org> wrote: > >> On Fri, Oct 06, 2023 at 12:25:18PM +0200, Ingo Molnar wrote: >> > find_new_ilb() returns nr_cpu_ids on failure - which is a weird >> > choice in itself: not only is it a global variable, it is >> > a +1 out of bounds CPU index... >> >> FWIW this is what all the cpumask bitops return when they've exhausted >> the mask. Eg. no bits left set etc.. > > yeah, which then results in type-forcing uglies like: > > kernel/events/core.c: if ((unsigned)cpu >= nr_cpu_ids) { > kernel/events/core.c: if ((unsigned)cpu >= nr_cpu_ids) { > kernel/smp.c: if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
I can't see why we'd want smp_call_function_single*() / generic_exec_single() to take a signed int as input, shouldn't this just be unsigned?
The perf thing does look like it wants signed though...
> > :-/ > > So I don't think this is a particularly well thought-out interface. > > Thanks, > > Ingo
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