On 18/08/22 15:38, Yury Norov wrote: > On Wed, Aug 17, 2022 at 06:58:09PM +0100, Valentin Schneider wrote: >> for_each_cpu_and() is very convenient as it saves having to allocate a >> temporary cpumask to store the result of cpumask_and(). The same issue >> applies to cpumask_andnot() which doesn't actually need temporary storage >> for iteration purposes. >> >> Following what has been done for for_each_cpu_and(), introduce >> for_each_cpu_andnot(). >> >> Signed-off-by: Valentin Schneider <vschneid@xxxxxxxxxx> > > I'm concerned that this series doesn't give us real examples and tests > for the new API. If we take it as-is, we'll end up with a dead code for > a while, quite probably for long. > Tariq has at least two uses of for_each_numa_hop_cpu() (which uses for_each_cpu_andnot()) in net/mlx5e and net/enic). My plan here is to make sure the cpumask and sched/topology changes are OK, and then I'd let Tariq carry the whole set with actual users on top. I wouldn't want to see this merged without users, especially given the EXPORT_SYMBOL_GPL() in 3/5. > Can you please submit a new code with a real application for the new API? > Alternatively, you can rework some existing code. > > Briefly grepping, I found good candidate in a core code: __sched_core_flip(), > and one candidate in arch code: arch/powerpc/kernel/smp.c: update_coregroup_mask. > I believe there are much more. > Some of these look fairly trivial, I'll have a look around. > Regarding the test, I don't think it's strictly necessary to have it as soon as > we'll have real users, but it's always good to backup with tests. > That sounds sensible enough, I'll have a look at that. > Thanks, > Yury
