On 17/01/2023 16:27, Ulf Hansson wrote: > On Mon, 19 Dec 2022 at 16:15, Krzysztof Kozlowski > <krzysztof.kozlowski@xxxxxxxxxx> wrote: >> >> The PSCI cpuidle power domain in power_off callback uses >> __this_cpu_write() so it is PREEMPT_RT safe. This allows to use it in >> Realtime kernels and solves errors like: >> >> BUG: scheduling while atomic: swapper/2/0/0x00000002 >> Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT) >> Call trace: >> dump_backtrace.part.0+0xe0/0xf0 >> show_stack+0x18/0x40 >> dump_stack_lvl+0x68/0x84 >> dump_stack+0x18/0x34 >> __schedule_bug+0x60/0x80 >> __schedule+0x628/0x800 >> schedule_rtlock+0x28/0x5c >> rtlock_slowlock_locked+0x360/0xd30 >> rt_spin_lock+0x88/0xb0 >> genpd_lock_nested_spin+0x1c/0x30 >> genpd_power_off.part.0.isra.0+0x20c/0x2a0 >> genpd_runtime_suspend+0x150/0x2bc >> __rpm_callback+0x48/0x170 >> rpm_callback+0x6c/0x7c >> rpm_suspend+0x108/0x660 >> __pm_runtime_suspend+0x4c/0x8c >> __psci_enter_domain_idle_state.constprop.0+0x54/0xe0 >> psci_enter_domain_idle_state+0x18/0x2c >> cpuidle_enter_state+0x8c/0x4e0 >> cpuidle_enter+0x38/0x50 >> do_idle+0x248/0x2f0 >> cpu_startup_entry+0x24/0x30 >> secondary_start_kernel+0x130/0x154 >> __secondary_switched+0xb0/0xb4 >> >> Cc: Adrien Thierry <athierry@xxxxxxxxxx> >> Cc: Brian Masney <bmasney@xxxxxxxxxx> >> Cc: linux-rt-users@xxxxxxxxxxxxxxx >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> >> --- >> drivers/cpuidle/cpuidle-psci-domain.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c >> index c80cf9ddabd8..d15a91fb7048 100644 >> --- a/drivers/cpuidle/cpuidle-psci-domain.c >> +++ b/drivers/cpuidle/cpuidle-psci-domain.c >> @@ -62,7 +62,8 @@ static int psci_pd_init(struct device_node *np, bool use_osi) >> if (!pd_provider) >> goto free_pd; >> >> - pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN; >> + pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_RT_SAFE | \ >> + GENPD_FLAG_CPU_DOMAIN; > > My main concern with this, is that it will affect the parent domains > too. Whether those would be able to use the GENPD_FLAG_RT_SAFE or not, > is a different story. > > In one way or the other, I think it would be better to limit the > GENPD_FLAG_RT_SAFE to be used only for PREEMPT_RT kernels. I can do it... or maybe we should just drop the flags (RT and IRQ safe) when parent domain does not have it? Best regards, Krzysztof
