On Mon, Oct 03, 2022 at 04:34:15PM +0100, Valentin Schneider wrote:
> As suggested by Yury, this is the bitmap/cpumask specific bits of [1]. This now
> also contains an extra fix for blk_mq.
Patches ##2-5 look good to me, but I'd like to give them some testing.
Let's also wait for other comments, and if nothing wrong will be spotted,
I'll take it.
Thanks,
Yury
> This is based on top of Yury's bitmap-for-next [2].
>
> A note on treewide use of for_each_cpu_andnot()
> ===============================================
>
> I've used the below coccinelle script to find places that could be patched (I
> couldn't figure out the valid syntax to patch from coccinelle itself):
>
> ,-----
> @tmpandnot@
> expression tmpmask;
> iterator for_each_cpu;
> position p;
> statement S;
> @@
> cpumask_andnot(tmpmask, ...);
>
> ...
>
> (
> for_each_cpu@p(..., tmpmask, ...)
> S
> |
> for_each_cpu@p(..., tmpmask, ...)
> {
> ...
> }
> )
>
> @script:python depends on tmpandnot@
> p << tmpandnot.p;
> @@
> coccilib.report.print_report(p[0], "andnot loop here")
> '-----
>
> Which yields (against c40e8341e3b3):
>
> .//arch/powerpc/kernel/smp.c:1587:1-13: andnot loop here
> .//arch/powerpc/kernel/smp.c:1530:1-13: andnot loop here
> .//arch/powerpc/kernel/smp.c:1440:1-13: andnot loop here
> .//arch/powerpc/platforms/powernv/subcore.c:306:2-14: andnot loop here
> .//arch/x86/kernel/apic/x2apic_cluster.c:62:1-13: andnot loop here
> .//drivers/acpi/acpi_pad.c:110:1-13: andnot loop here
> .//drivers/cpufreq/armada-8k-cpufreq.c:148:1-13: andnot loop here
> .//drivers/cpufreq/powernv-cpufreq.c:931:1-13: andnot loop here
> .//drivers/net/ethernet/sfc/efx_channels.c:73:1-13: andnot loop here
> .//drivers/net/ethernet/sfc/siena/efx_channels.c:73:1-13: andnot loop here
> .//kernel/sched/core.c:345:1-13: andnot loop here
> .//kernel/sched/core.c:366:1-13: andnot loop here
> .//net/core/dev.c:3058:1-13: andnot loop here
>
> A lot of those are actually of the shape
>
> for_each_cpu(cpu, mask) {
> ...
> cpumask_andnot(mask, ...);
> }
>
> I think *some* of the powerpc ones would be a match for for_each_cpu_andnot(),
> but I decided to just stick to the one obvious one in __sched_core_flip().
>
> [1]: https://lore.kernel.org/all/20220923132527.1001870-1-vschneid@xxxxxxxxxx/
> [2]: https://github.com/norov/linux.git/ -b bitmap-for-next
>
> Cheers,
> Valentin
>
> Valentin Schneider (5):
> blk_mq: Fix cpumask_check() warning in blk_mq_hctx_next_cpu()
> lib/find_bit: Introduce find_next_andnot_bit()
> cpumask: Introduce for_each_cpu_andnot()
> lib/test_cpumask: Add for_each_cpu_and(not) tests
> sched/core: Merge cpumask_andnot()+for_each_cpu() into
> for_each_cpu_andnot()
>
> block/blk-mq.c | 9 +++++++--
> include/linux/cpumask.h | 18 ++++++++++++++++++
> include/linux/find.h | 38 ++++++++++++++++++++++++++++++++++++++
> kernel/sched/core.c | 5 +----
> lib/cpumask_kunit.c | 19 +++++++++++++++++++
> lib/find_bit.c | 9 +++++++++
> 6 files changed, 92 insertions(+), 6 deletions(-)
>
> --
> 2.31.1
