From 9ca12ac04bb7d7cfb28aa549dcd3d15761f15543 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Thu, 11 Apr 2019 13:34:46 +1000 Subject: kernel/cpu: Allow non-zero CPU to be primary for suspend / kexec freeze This patch provides an arch option, ARCH_SUSPEND_NONZERO_CPU, to opt-in to allowing suspend to occur on one of the housekeeping CPUs rather than hardcoded CPU0. This will allow CPU0 to be a nohz_full CPU with a later change. It may be possible for platforms with hardware/firmware restrictions on suspend/wake effectively support this by handing off the final stage to CPU0 when kernel housekeeping is no longer required. Another option is to make housekeeping / nohz_full mask dynamic at runtime, but the complexity could not be justified at this time. Signed-off-by: Nicholas Piggin Signed-off-by: Peter Zijlstra (Intel) Cc: Frederic Weisbecker Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rafael J . Wysocki Cc: Thomas Gleixner Cc: linuxppc-dev@lists.ozlabs.org Link: https://lkml.kernel.org/r/20190411033448.20842-4-npiggin@gmail.com Signed-off-by: Ingo Molnar --- kernel/cpu.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'kernel/cpu.c') diff --git a/kernel/cpu.c b/kernel/cpu.c index 6754f3ecfd94..d1bf6e2b4752 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -1199,8 +1200,15 @@ int freeze_secondary_cpus(int primary) int cpu, error = 0; cpu_maps_update_begin(); - if (!cpu_online(primary)) + if (primary == -1) { primary = cpumask_first(cpu_online_mask); + if (!housekeeping_cpu(primary, HK_FLAG_TIMER)) + primary = housekeeping_any_cpu(HK_FLAG_TIMER); + } else { + if (!cpu_online(primary)) + primary = cpumask_first(cpu_online_mask); + } + /* * We take down all of the non-boot CPUs in one shot to avoid races * with the userspace trying to use the CPU hotplug at the same time -- cgit v1.2.3-58-ga151