lkml.org 
[lkml]   [2023]   [Jan]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 2/5] cpuidle: psci: Mark as PREEMPT_RT safe
From
On 17/01/2023 16:27, Ulf Hansson wrote:
> On Mon, 19 Dec 2022 at 16:15, Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> 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@redhat.com>
>> Cc: Brian Masney <bmasney@redhat.com>
>> Cc: linux-rt-users@vger.kernel.org
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> ---
>> 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

\
 
 \ /
  Last update: 2023-03-26 23:47    [W:0.064 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site