[PATCH V2] arm64: skip register_cpufreq_notifier on ACPI-based systems

[PATCH V2] arm64: skip register_cpufreq_notifier on ACPI-based systems

[Prashanth Prakash]

On ACPI based systems where the topology is setup using the API
store_cpu_topology, at the moment we do not have necessary code
to parse cpu capacity and handle cpufreq notifier, thus
resulting in a kernel panic.

Stack:
        init_cpu_capacity_callback+0xb4/0x1c8
        notifier_call_chain+0x5c/0xa0
        __blocking_notifier_call_chain+0x58/0xa0
        blocking_notifier_call_chain+0x3c/0x50
        cpufreq_set_policy+0xe4/0x328
        cpufreq_init_policy+0x80/0x100
        cpufreq_online+0x418/0x710
        cpufreq_add_dev+0x118/0x180
        subsys_interface_register+0xa4/0xf8
        cpufreq_register_driver+0x1c0/0x298
        cppc_cpufreq_init+0xdc/0x1000 [cppc_cpufreq]
        do_one_initcall+0x5c/0x168
        do_init_module+0x64/0x1e4
        load_module+0x130c/0x14d0
        SyS_finit_module+0x108/0x120
        el0_svc_naked+0x24/0x28

Fixes: 7202bde8b7ae ("arm64: parse cpu capacity-dmips-mhz from DT")
Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
---
 arch/arm64/kernel/topology.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 23e9e13..701f7a7 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -11,6 +11,7 @@
  * for more details.
  */
 
+#include <linux/acpi.h>
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/init.h>
@@ -209,7 +210,12 @@ static void normalize_cpu_capacity(void)
 
 static int __init register_cpufreq_notifier(void)
 {
-	if (cap_parsing_failed)
+	/*
+	 * on ACPI-based systems we need to use the default cpu capacity
+	 * until we have the necessary code to parse the cpu capacity, so
+	 * skip registering cpufreq notifier.
+	 */
+	if (!acpi_disabled || cap_parsing_failed)
 		return -EINVAL;
 
 	if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
-- 
Qualcomm Datacenter Technologies on behalf of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

[PATCH V2] arm64: skip register_cpufreq_notifier on ACPI-based systems

[Will Deacon]

On Thu, Jan 26, 2017 at 11:08:32AM -0700, Prashanth Prakash wrote:
> On ACPI based systems where the topology is setup using the API
> store_cpu_topology, at the moment we do not have necessary code
> to parse cpu capacity and handle cpufreq notifier, thus
> resulting in a kernel panic.
> 
> Stack:
>         init_cpu_capacity_callback+0xb4/0x1c8
>         notifier_call_chain+0x5c/0xa0
>         __blocking_notifier_call_chain+0x58/0xa0
>         blocking_notifier_call_chain+0x3c/0x50
>         cpufreq_set_policy+0xe4/0x328
>         cpufreq_init_policy+0x80/0x100
>         cpufreq_online+0x418/0x710
>         cpufreq_add_dev+0x118/0x180
>         subsys_interface_register+0xa4/0xf8
>         cpufreq_register_driver+0x1c0/0x298
>         cppc_cpufreq_init+0xdc/0x1000 [cppc_cpufreq]
>         do_one_initcall+0x5c/0x168
>         do_init_module+0x64/0x1e4
>         load_module+0x130c/0x14d0
>         SyS_finit_module+0x108/0x120
>         el0_svc_naked+0x24/0x28
> 
> Fixes: 7202bde8b7ae ("arm64: parse cpu capacity-dmips-mhz from DT")
> Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
> ---
>  arch/arm64/kernel/topology.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)

Acked-by: Will Deacon <will.deacon@arm.com>

Catalin -- this resolves a panic, so please take it for 4.10

Will

[PATCH V2] arm64: skip register_cpufreq_notifier on ACPI-based systems

[Catalin Marinas]

On Thu, Jan 26, 2017 at 06:11:17PM +0000, Will Deacon wrote:
> On Thu, Jan 26, 2017 at 11:08:32AM -0700, Prashanth Prakash wrote:
> > On ACPI based systems where the topology is setup using the API
> > store_cpu_topology, at the moment we do not have necessary code
> > to parse cpu capacity and handle cpufreq notifier, thus
> > resulting in a kernel panic.
> > 
> > Stack:
> >         init_cpu_capacity_callback+0xb4/0x1c8
> >         notifier_call_chain+0x5c/0xa0
> >         __blocking_notifier_call_chain+0x58/0xa0
> >         blocking_notifier_call_chain+0x3c/0x50
> >         cpufreq_set_policy+0xe4/0x328
> >         cpufreq_init_policy+0x80/0x100
> >         cpufreq_online+0x418/0x710
> >         cpufreq_add_dev+0x118/0x180
> >         subsys_interface_register+0xa4/0xf8
> >         cpufreq_register_driver+0x1c0/0x298
> >         cppc_cpufreq_init+0xdc/0x1000 [cppc_cpufreq]
> >         do_one_initcall+0x5c/0x168
> >         do_init_module+0x64/0x1e4
> >         load_module+0x130c/0x14d0
> >         SyS_finit_module+0x108/0x120
> >         el0_svc_naked+0x24/0x28
> > 
> > Fixes: 7202bde8b7ae ("arm64: parse cpu capacity-dmips-mhz from DT")
> > Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
> > ---
> >  arch/arm64/kernel/topology.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> Acked-by: Will Deacon <will.deacon@arm.com>
> 
> Catalin -- this resolves a panic, so please take it for 4.10

Applied. Thanks.

-- 
Catalin