Re: [PATCH v2 2/5] cpuidle: psci: Mark as PREEMPT_RT safe
From: Ulf Hansson <hidden>
Date: 2023-01-17 15:28:53
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linux-pm, linux-rt-users, lkml
On Mon, 19 Dec 2022 at 16:15, Krzysztof Kozlowski [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> Cc: Brian Masney <bmasney@redhat.com> Cc: linux-rt-users@vger.kernel.org Signed-off-by: Krzysztof Kozlowski <redacted> --- 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.
/* Allow power off when OSI has been successfully enabled. */
if (use_osi)
--
2.34.1Kind regards Uffe _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel