ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable
PATCH v4 1/1 ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable
Writes to /sys/.../cpuX/online fail if we determine the platform doesn't support hotplug for that CPU. Furthermore, if the cpu_die op isn't specified the system hangs when we try to offline a CPU and it comes right back online unexpectedly. Let's figure this stuff out before we make the sysfs nodes so that the online file doesn't even exist if it isn't (at least sometimes) possible to hotplug the CPU.
Add a new 'cpu_can_disable' op and repoint all 'cpu_disable' implementations at it because all implementers use the op to indicate if a CPU can be hotplugged or not in a static fashion. With PSCI we may need to add a 'cpu_disable' op so that the secure OS can be migrated off the CPU we're trying to hotplug. In this case, the 'cpu_can_disable' op will indicate that all CPUs are hotpluggable by returning true, but the 'cpu_disable' op will make a PSCI migration call and occasionally fail, denying the hotplug of a CPU. This shouldn't be any worse than x86 where we may indicate that all CPUs are hotpluggable but occasionally we can't offline a CPU due to check_irq_vectors_for_cpu_disable() failing to find a CPU to move vectors to.
---
Changes since v3:
* Return bool instead of int from 'cpu_can_disable' op
Changes since v2:
* Left cpu_disable op in place
* Split out shmobile function deletion
arch/arm/common/mcpm_platsmp.c | 12 ++++-------- arch/arm/include/asm/smp.h | 10 ++++++++++ arch/arm/kernel/setup.c | 2 +- arch/arm/kernel/smp.c | 15 ++++++++++++++- arch/arm/mach-shmobile/common.h | 2 +- arch/arm/mach-shmobile/platsmp.c | 4 ++-- arch/arm/mach-shmobile/smp-r8a7790.c | 2 +- arch/arm/mach-shmobile/smp-r8a7791.c | 2 +- arch/arm/mach-shmobile/smp-sh73a0.c | 2 +- 9 files changed, 35 insertions(+), 16 deletions(-)
arch/arm/common/mcpm_platsmp.c +4 -8
@@ -65,14 +65,10 @@ static int mcpm_cpu_kill(unsigned int cpu)return !mcpm_wait_for_cpu_powerdown (pcpu, pcluster); } -static int mcpm_cpu_disable (unsigned int cpu) +static bool mcpm_cpu_can_disable (unsigned int cpu) { -/* -* We assume all CPUs may be shut down. -* This would be the hook to use for eventual Secure -* OS migration requests as described in the PSCI spec. -*/ -return 0 ; +/* We assume all CPUs may be shut down. */ +return true; }static void mcpm_cpu_die (unsigned int cpu)
@@ -92,7 +88,7 @@ static struct smp_operations __initdata mcpm_smp_ops = { .smp_secondary_init = mcpm_secondary_init, #ifdef CONFIG_HOTPLUG_CPU .cpu_kill = mcpm_cpu_kill, - .cpu_disable = mcpm_cpu_disable, + .cpu_can_disable = mcpm_cpu_can_disable, .cpu_die = mcpm_cpu_die, #endif };
arch/arm/include/asm/smp.h +10 -0
@@ -104,6 +104,7 @@ struct smp_operations {#ifdef CONFIG_HOTPLUG_CPU int (*cpu_kill)(unsigned int cpu);void (*cpu_die)(unsigned int cpu); +bool (*cpu_can_disable)(unsigned int cpu);int (*cpu_disable)(unsigned int cpu);#endif #endif
@@ -123,4 +124,13 @@ struct of_cpu_method {*/ extern void smp_set_ops (struct smp_operations *); +#ifdef CONFIG_HOTPLUG_CPU +extern int platform_can_hotplug_cpu (unsigned int cpu); +#else +static inline int platform_can_hotplug_cpu (unsigned int cpu) +{ +return 0 ; +} +#endif +#endif /* ifndef __ASM_ARM_SMP_H */
arch/arm/kernel/setup.c +1 -1
@@ -992,7 +992,7 @@ static int __init topology_init(void)for_each_possible_cpu (cpu) {struct cpuinfo_arm *cpuinfo = &per_cpu (cpu_data, cpu); - cpuinfo->cpu.hotpluggable =1 ; + cpuinfo->cpu.hotpluggable =platform_can_hotplug_cpu (cpu);register_cpu (&cpuinfo->cpu, cpu); }
arch/arm/kernel/smp.c +14 -1
@@ -168,13 +168,26 @@ static int platform_cpu_disable(unsigned int cpu)if (smp_ops.cpu_disable)return smp_ops.cpu_disable (cpu); +return 0 ; +} + +int platform_can_hotplug_cpu (unsigned int cpu) +{ +/* cpu_die must be specified to support hotplug */ +if (!smp_ops.cpu_die) +return 0 ; + +if (smp_ops.cpu_can_disable) +return smp_ops.cpu_can_disable (cpu); +/* * By default, allow disabling all CPUs except the first one, * since this is special on a lot of platforms, e.g. because * of clock tick interrupts. */ -return cpu ==0 ? -EPERM :0 ; +return cpu !=0 ; } +/* * __cpu_disable runs on the processor to be shutdown. */
arch/arm/mach-shmobile/common.h +1 -1
@@ -13,7 +13,7 @@ extern void shmobile_smp_boot(void);extern void shmobile_smp_sleep (void );extern void shmobile_smp_hook (unsigned int cpu,unsigned long fn,unsigned long arg); -extern int shmobile_smp_cpu_disable (unsigned int cpu); +extern bool shmobile_smp_cpu_can_disable (unsigned int cpu);extern void shmobile_invalidate_start (void );extern void shmobile_boot_scu (void );extern void shmobile_smp_scu_prepare_cpus (unsigned int max_cpus);
arch/arm/mach-shmobile/platsmp.c +2 -2
@@ -31,8 +31,8 @@ void shmobile_smp_hook(unsigned int cpu, unsigned long fn, unsigned long arg) }#ifdef CONFIG_HOTPLUG_CPU -int shmobile_smp_cpu_disable (unsigned int cpu) +bool shmobile_smp_cpu_can_disable (unsigned int cpu) { -return 0 ;/* Hotplug of any CPU is supported */ +return true;/* Hotplug of any CPU is supported */ }#endif
arch/arm/mach-shmobile/smp-r8a7790.c +1 -1
@@ -64,7 +64,7 @@ struct smp_operations r8a7790_smp_ops __initdata = { .smp_prepare_cpus = r8a7790_smp_prepare_cpus, .smp_boot_secondary = shmobile_smp_apmu_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU - .cpu_disable = shmobile_smp_cpu_disable, + .cpu_can_disable = shmobile_smp_cpu_can_disable, .cpu_die = shmobile_smp_apmu_cpu_die, .cpu_kill = shmobile_smp_apmu_cpu_kill, #endif
arch/arm/mach-shmobile/smp-r8a7791.c +1 -1
@@ -58,7 +58,7 @@ struct smp_operations r8a7791_smp_ops __initdata = { .smp_prepare_cpus = r8a7791_smp_prepare_cpus, .smp_boot_secondary = r8a7791_smp_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU - .cpu_disable = shmobile_smp_cpu_disable, + .cpu_can_disable = shmobile_smp_cpu_can_disable, .cpu_die = shmobile_smp_apmu_cpu_die, .cpu_kill = shmobile_smp_apmu_cpu_kill, #endif
arch/arm/mach-shmobile/smp-sh73a0.c +1 -1
@@ -68,7 +68,7 @@ struct smp_operations sh73a0_smp_ops __initdata = { .smp_prepare_cpus = sh73a0_smp_prepare_cpus, .smp_boot_secondary = sh73a0_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU - .cpu_disable = shmobile_smp_cpu_disable, + .cpu_can_disable = shmobile_smp_cpu_can_disable, .cpu_die = shmobile_smp_scu_cpu_die, .cpu_kill = shmobile_smp_scu_cpu_kill, #endif
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Quoted 21 lines · Stephen Boyd
Writes to
/sys/.../cpuX/onlinefail if we determine the platform doesn't support hotplug for that CPU. Furthermore, if thecpu_dieop isn't specified the system hangs when we try to offline a CPU and it comes right back online unexpectedly. Let's figure this stuff out before we make the sysfs nodes so that the online file doesn't even exist if it isn't (at least sometimes) possible to hotplug the CPU.Add a new '
cpu_can_disable' op and repoint all 'cpu_disable' implementations at it because all implementers use the op to indicate if a CPU can be hotplugged or not in a static fashion. With PSCI we may need to add a 'cpu_disable' op so that the secure OS can be migrated off the CPU we're trying to hotplug. In this case, the 'cpu_can_disable' op will indicate that all CPUs are hotpluggable by returning true, but the 'cpu_disable' op will make a PSCI migration call and occasionally fail, denying the hotplug of a CPU. This shouldn't be any worse than x86 where we may indicate that all CPUs are hotpluggable but occasionally we can't offline a CPU due tocheck_irq_vectors_for_cpu_disable()failing to find a CPU to move vectors to.
Quoted 9 lines
Cc Mark Rutland <[email protected]>Cc Nicolas Pitre <[email protected]>Cc Dave Martin <[email protected]>Cc Simon Horman <[email protected]>Cc Magnus Damm <[email protected]>Cc <[email protected]>Cc Tyler Baker <[email protected]>Cc Geert Uytterhoeven <[email protected]>Signed-off-by Stephen Boyd <[email protected]>
I think this is fine, but I'd like to see some acks for it. As it's mostly core ARM stuff, it should be merged through my tree unless there is a known conflict with arm-soc. Thanks.
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Quoted 32 lines · Russell King - ARM Linux
Quoted 21 lines · Stephen Boyd
Writes to
/sys/.../cpuX/onlinefail if we determine the platform doesn't support hotplug for that CPU. Furthermore, if thecpu_dieop isn't specified the system hangs when we try to offline a CPU and it comes right back online unexpectedly. Let's figure this stuff out before we make the sysfs nodes so that the online file doesn't even exist if it isn't (at least sometimes) possible to hotplug the CPU.Add a new '
cpu_can_disable' op and repoint all 'cpu_disable' implementations at it because all implementers use the op to indicate if a CPU can be hotplugged or not in a static fashion. With PSCI we may need to add a 'cpu_disable' op so that the secure OS can be migrated off the CPU we're trying to hotplug. In this case, the 'cpu_can_disable' op will indicate that all CPUs are hotpluggable by returning true, but the 'cpu_disable' op will make a PSCI migration call and occasionally fail, denying the hotplug of a CPU. This shouldn't be any worse than x86 where we may indicate that all CPUs are hotpluggable but occasionally we can't offline a CPU due tocheck_irq_vectors_for_cpu_disable()failing to find a CPU to move vectors to.Quoted 9 lines
Cc Mark Rutland <[email protected]>Cc Nicolas Pitre <[email protected]>Cc Dave Martin <[email protected]>Cc Simon Horman <[email protected]>Cc Magnus Damm <[email protected]>Cc <[email protected]>Cc Tyler Baker <[email protected]>Cc Geert Uytterhoeven <[email protected]>Signed-off-by Stephen Boyd <[email protected]>
Quoted 3 lines
I think this is fine, but I'd like to see some acks for it. As it's mostly core ARM stuff, it should be merged through my tree unless there is a known conflict with arm-soc. Thanks.
I'm happy with the shmobile portions and have verified that they don't conflict with anything I have queued up for v4.1.
So in the context of that release, for the shmobile portion:
I also tested, and the effected shmobile boards still seem to boot with this patch applied.
Hi Stephen,
Quoted 112 lines · Stephen Boyd
Writes to
/sys/.../cpuX/onlinefail if we determine the platform doesn't support hotplug for that CPU. Furthermore, if thecpu_dieop isn't specified the system hangs when we try to offline a CPU and it comes right back online unexpectedly. Let's figure this stuff out before we make the sysfs nodes so that the online file doesn't even exist if it isn't (at least sometimes) possible to hotplug the CPU.Add a new '
cpu_can_disable' op and repoint all 'cpu_disable' implementations at it because all implementers use the op to indicate if a CPU can be hotplugged or not in a static fashion. With PSCI we may need to add a 'cpu_disable' op so that the secure OS can be migrated off the CPU we're trying to hotplug. In this case, the 'cpu_can_disable' op will indicate that all CPUs are hotpluggable by returning true, but the 'cpu_disable' op will make a PSCI migration call and occasionally fail, denying the hotplug of a CPU. This shouldn't be any worse than x86 where we may indicate that all CPUs are hotpluggable but occasionally we can't offline a CPU due tocheck_irq_vectors_for_cpu_disable()failing to find a CPU to move vectors to.Cc Mark Rutland <[email protected]>Cc Nicolas Pitre <[email protected]>Cc Dave Martin <[email protected]>Cc Simon Horman <[email protected]>Cc Magnus Damm <[email protected]>Cc <[email protected]>Cc Tyler Baker <[email protected]>Cc Geert Uytterhoeven <[email protected]>Signed-off-by Stephen Boyd <[email protected]>---
Changes since v3:
* Return bool instead of int from 'cpu_can_disable' opChanges since v2:
* Leftcpu_disableop in place
* Split out shmobile function deletionarch/arm/common/mcpm_platsmp.c | 12 ++++-------- arch/arm/include/asm/smp.h | 10 ++++++++++ arch/arm/kernel/setup.c | 2 +- arch/arm/kernel/smp.c | 15 ++++++++++++++- arch/arm/mach-shmobile/common.h | 2 +- arch/arm/mach-shmobile/platsmp.c | 4 ++-- arch/arm/mach-shmobile/smp-r8a7790.c | 2 +- arch/arm/mach-shmobile/smp-r8a7791.c | 2 +- arch/arm/mach-shmobile/smp-sh73a0.c | 2 +- 9 files changed, 35 insertions(+), 16 deletions(-)arch/arm/common/mcpm_platsmp.c +4
-8@@ -65,14 +65,10 @@ static int mcpm_cpu_kill(unsigned int cpu)return !mcpm_wait_for_cpu_powerdown (pcpu, pcluster); } -static int mcpm_cpu_disable (unsigned int cpu) +static bool mcpm_cpu_can_disable (unsigned int cpu) { -/* -* We assume all CPUs may be shut down. -* This would be the hook to use for eventual Secure -* OS migration requests as described in the PSCI spec. -*/ -return 0 ; +/* We assume all CPUs may be shut down. */ +return true; }static void mcpm_cpu_die (unsigned int cpu)@@ -92,7 +88,7 @@ static struct smp_operations __initdata mcpm_smp_ops = { .smp_secondary_init = mcpm_secondary_init, #ifdef CONFIG_HOTPLUG_CPU .cpu_kill = mcpm_cpu_kill, - .cpu_disable = mcpm_cpu_disable, + .cpu_can_disable = mcpm_cpu_can_disable, .cpu_die = mcpm_cpu_die, #endif };arch/arm/include/asm/smp.h +10
-0@@ -104,6 +104,7 @@ struct smp_operations {#ifdef CONFIG_HOTPLUG_CPU int (*cpu_kill)(unsigned int cpu);void (*cpu_die)(unsigned int cpu); +bool (*cpu_can_disable)(unsigned int cpu);int (*cpu_disable)(unsigned int cpu);#endif #endif @@ -123,4 +124,13 @@ struct of_cpu_method {*/ extern void smp_set_ops (struct smp_operations *); +#ifdef CONFIG_HOTPLUG_CPU +extern int platform_can_hotplug_cpu (unsigned int cpu); +#else +static inline int platform_can_hotplug_cpu (unsigned int cpu) +{ +return 0 ; +} +#endif +#endif /* ifndef __ASM_ARM_SMP_H */ arch/arm/kernel/setup.c +0
-0
arch/arm/kernel/setup.c static int __init topology_init(void) · line 998
Quoted 8 lines
arch/arm/kernel/setup.c +1
-1@@ -992,7 +992,7 @@ static int __init topology_init(void)for_each_possible_cpu (cpu) {struct cpuinfo_arm *cpuinfo = &per_cpu (cpu_data, cpu); - cpuinfo->cpu.hotpluggable =1 ; + cpuinfo->cpu.hotpluggable =platform_can_hotplug_cpu (cpu);register_cpu (&cpuinfo->cpu, cpu); }
When I tested this patch before I only tried building multi_v7_defconfig (which built fine) however I've added this patch to my to-build branch and sent it through the CI loop. It appears that there quite a few build errors on the other defconfigs[0][1].
../arch/arm/kernel/setup.c: In function 'topology_init':../arch/arm/kernel/setup.c:977:3: error: implicit declaration of function 'platform_can_hotplug_cpu' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[2]: *** [arch/arm/kernel/setup.o] Error 1
Quoted 100 lines
arch/arm/kernel/smp.c +14
-1@@ -168,13 +168,26 @@ static int platform_cpu_disable(unsigned int cpu)if (smp_ops.cpu_disable)return smp_ops.cpu_disable (cpu); +return 0 ; +} + +int platform_can_hotplug_cpu (unsigned int cpu) +{ +/* cpu_die must be specified to support hotplug */ +if (!smp_ops.cpu_die) +return 0 ; + +if (smp_ops.cpu_can_disable) +return smp_ops.cpu_can_disable (cpu); +/* * By default, allow disabling all CPUs except the first one, * since this is special on a lot of platforms, e.g. because * of clock tick interrupts. */ -return cpu ==0 ? -EPERM :0 ; +return cpu !=0 ; } +/* * __cpu_disable runs on the processor to be shutdown. */ arch/arm/mach-shmobile/common.h +1
-1@@ -13,7 +13,7 @@ extern void shmobile_smp_boot(void);extern void shmobile_smp_sleep (void );extern void shmobile_smp_hook (unsigned int cpu,unsigned long fn,unsigned long arg); -extern int shmobile_smp_cpu_disable (unsigned int cpu); +extern bool shmobile_smp_cpu_can_disable (unsigned int cpu);extern void shmobile_invalidate_start (void );extern void shmobile_boot_scu (void );extern void shmobile_smp_scu_prepare_cpus (unsigned int max_cpus);arch/arm/mach-shmobile/platsmp.c +2
-2@@ -31,8 +31,8 @@ void shmobile_smp_hook(unsigned int cpu, unsigned long fn, unsigned long arg) }#ifdef CONFIG_HOTPLUG_CPU -int shmobile_smp_cpu_disable (unsigned int cpu) +bool shmobile_smp_cpu_can_disable (unsigned int cpu) { -return 0 ;/* Hotplug of any CPU is supported */ +return true;/* Hotplug of any CPU is supported */ }#endif arch/arm/mach-shmobile/smp-r8a7790.c +1
-1@@ -64,7 +64,7 @@ struct smp_operations r8a7790_smp_ops __initdata = { .smp_prepare_cpus = r8a7790_smp_prepare_cpus, .smp_boot_secondary = shmobile_smp_apmu_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU - .cpu_disable = shmobile_smp_cpu_disable, + .cpu_can_disable = shmobile_smp_cpu_can_disable, .cpu_die = shmobile_smp_apmu_cpu_die, .cpu_kill = shmobile_smp_apmu_cpu_kill, #endifarch/arm/mach-shmobile/smp-r8a7791.c +1
-1@@ -58,7 +58,7 @@ struct smp_operations r8a7791_smp_ops __initdata = { .smp_prepare_cpus = r8a7791_smp_prepare_cpus, .smp_boot_secondary = r8a7791_smp_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU - .cpu_disable = shmobile_smp_cpu_disable, + .cpu_can_disable = shmobile_smp_cpu_can_disable, .cpu_die = shmobile_smp_apmu_cpu_die, .cpu_kill = shmobile_smp_apmu_cpu_kill, #endifarch/arm/mach-shmobile/smp-sh73a0.c +1
-2@@ -68,7 +68,7 @@ struct smp_operations sh73a0_smp_ops __initdata = { .smp_prepare_cpus = sh73a0_smp_prepare_cpus, .smp_boot_secondary = sh73a0_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU - .cpu_disable = shmobile_smp_cpu_disable, + .cpu_can_disable = shmobile_smp_cpu_can_disable, .cpu_die = shmobile_smp_scu_cpu_die, .cpu_kill = shmobile_smp_scu_cpu_kill, #endif --
Quoted 3 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
Cheers,
Tyler
[0] http://kernelci.org/build/tbaker/kernel/v4.0-rc6-189-g9108e703ce6d/
[1] http://kernelci.org/boot/all/job/tbaker/kernel/v4.0-rc6-189-g9108e703ce6d/
Quoted 128 lines · Tyler Baker
Hi Stephen,
Quoted 112 lines · Stephen Boyd
Writes to
/sys/.../cpuX/onlinefail if we determine the platform doesn't support hotplug for that CPU. Furthermore, if thecpu_dieop isn't specified the system hangs when we try to offline a CPU and it comes right back online unexpectedly. Let's figure this stuff out before we make the sysfs nodes so that the online file doesn't even exist if it isn't (at least sometimes) possible to hotplug the CPU.Add a new '
cpu_can_disable' op and repoint all 'cpu_disable' implementations at it because all implementers use the op to indicate if a CPU can be hotplugged or not in a static fashion. With PSCI we may need to add a 'cpu_disable' op so that the secure OS can be migrated off the CPU we're trying to hotplug. In this case, the 'cpu_can_disable' op will indicate that all CPUs are hotpluggable by returning true, but the 'cpu_disable' op will make a PSCI migration call and occasionally fail, denying the hotplug of a CPU. This shouldn't be any worse than x86 where we may indicate that all CPUs are hotpluggable but occasionally we can't offline a CPU due tocheck_irq_vectors_for_cpu_disable()failing to find a CPU to move vectors to.Cc Mark Rutland <[email protected]>Cc Nicolas Pitre <[email protected]>Cc Dave Martin <[email protected]>Cc Simon Horman <[email protected]>Cc Magnus Damm <[email protected]>Cc <[email protected]>Cc Tyler Baker <[email protected]>Cc Geert Uytterhoeven <[email protected]>Signed-off-by Stephen Boyd <[email protected]>---
Changes since v3:
* Return bool instead of int from 'cpu_can_disable' opChanges since v2:
* Leftcpu_disableop in place
* Split out shmobile function deletionarch/arm/common/mcpm_platsmp.c | 12 ++++-------- arch/arm/include/asm/smp.h | 10 ++++++++++ arch/arm/kernel/setup.c | 2 +- arch/arm/kernel/smp.c | 15 ++++++++++++++- arch/arm/mach-shmobile/common.h | 2 +- arch/arm/mach-shmobile/platsmp.c | 4 ++-- arch/arm/mach-shmobile/smp-r8a7790.c | 2 +- arch/arm/mach-shmobile/smp-r8a7791.c | 2 +- arch/arm/mach-shmobile/smp-sh73a0.c | 2 +- 9 files changed, 35 insertions(+), 16 deletions(-)arch/arm/common/mcpm_platsmp.c +4
-8@@ -65,14 +65,10 @@ static int mcpm_cpu_kill(unsigned int cpu)return !mcpm_wait_for_cpu_powerdown (pcpu, pcluster); } -static int mcpm_cpu_disable (unsigned int cpu) +static bool mcpm_cpu_can_disable (unsigned int cpu) { -/* -* We assume all CPUs may be shut down. -* This would be the hook to use for eventual Secure -* OS migration requests as described in the PSCI spec. -*/ -return 0 ; +/* We assume all CPUs may be shut down. */ +return true; }static void mcpm_cpu_die (unsigned int cpu)@@ -92,7 +88,7 @@ static struct smp_operations __initdata mcpm_smp_ops = { .smp_secondary_init = mcpm_secondary_init, #ifdef CONFIG_HOTPLUG_CPU .cpu_kill = mcpm_cpu_kill, - .cpu_disable = mcpm_cpu_disable, + .cpu_can_disable = mcpm_cpu_can_disable, .cpu_die = mcpm_cpu_die, #endif };arch/arm/include/asm/smp.h +10
-0@@ -104,6 +104,7 @@ struct smp_operations {#ifdef CONFIG_HOTPLUG_CPU int (*cpu_kill)(unsigned int cpu);void (*cpu_die)(unsigned int cpu); +bool (*cpu_can_disable)(unsigned int cpu);int (*cpu_disable)(unsigned int cpu);#endif #endif @@ -123,4 +124,13 @@ struct of_cpu_method {*/ extern void smp_set_ops (struct smp_operations *); +#ifdef CONFIG_HOTPLUG_CPU +extern int platform_can_hotplug_cpu (unsigned int cpu); +#else +static inline int platform_can_hotplug_cpu (unsigned int cpu) +{ +return 0 ; +} +#endif +#endif /* ifndef __ASM_ARM_SMP_H */ arch/arm/kernel/setup.c +0
-0arch/arm/kernel/setup.c static int __init topology_init(void) · line 998
Quoted 8 lines
arch/arm/kernel/setup.c +1
-1@@ -992,7 +992,7 @@ static int __init topology_init(void)for_each_possible_cpu (cpu) {struct cpuinfo_arm *cpuinfo = &per_cpu (cpu_data, cpu); - cpuinfo->cpu.hotpluggable =1 ; + cpuinfo->cpu.hotpluggable =platform_can_hotplug_cpu (cpu);register_cpu (&cpuinfo->cpu, cpu); }When I tested this patch before I only tried building
multi_v7_defconfig(which built fine) however I've added this patch to my to-build branch and sent it through the CI loop. It appears that there quite a few build errors on the other defconfigs[0][1].
Quoted 7 lines
../arch/arm/kernel/setup.c: In function 'topology_init':../arch/arm/kernel/setup.c:977:3: error: implicit declaration of function 'platform_can_hotplug_cpu' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[2]: *** [arch/arm/kernel/setup.o] Error 1
Ah right. asm/smp.h is not included unless CONFIG_SMP=y. We can move it into smp_plat.h. I'll wait to see if there any other comments before sending an update.
---8<---
arch/arm/include/asm/smp.h +0 -9
@@ -124,13 +124,4 @@ struct of_cpu_method {*/ extern void smp_set_ops (struct smp_operations *); -#ifdef CONFIG_HOTPLUG_CPU -extern int platform_can_hotplug_cpu (unsigned int cpu); -#else -static inline int platform_can_hotplug_cpu (unsigned int cpu) -{ -return 0 ; -} -#endif -#endif /* ifndef __ASM_ARM_SMP_H */
arch/arm/include/asm/smp_plat.h +9 -0
@@ -106,4 +106,13 @@ static inline u32 mpidr_hash_size(void)extern int platform_can_cpu_hotplug (void ); +#ifdef CONFIG_HOTPLUG_CPU +extern int platform_can_hotplug_cpu (unsigned int cpu); +#else +static inline int platform_can_hotplug_cpu (unsigned int cpu) +{ +return 0 ; +} +#endif +#endif
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