Commit 3e8eb22f authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390: enforce CONFIG_HOTPLUG_CPU 



x86 and powerpc (partially) enforce already CONFIG_HOTPLUG_CPU. On
s390 it is enabled on all distributions by default since ages.
The only exception is our zfcpdump kernel.

However to simplify testing, enforce HOTPLUG_CPU. This was suggested
by Paul McKenney, since his rcutorture test environments for CONFIG_SMP=y
only support HOTPLUG_CPU=y.

Suggested-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
Acked-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent 67626fad

arch/s390/Kconfig

+0 −5
Original line number Diff line number Diff line
@@ -413,11 +413,6 @@ config NR_CPUS 


config HOTPLUG_CPU

	def_bool y

	prompt "Support for hot-pluggable CPUs"

	help

	  Say Y here to be able to turn CPUs off and on. CPUs

	  can be controlled through /sys/devices/system/cpu/cpu#.

	  Say N if you want to disable CPU hotplug.



# Some NUMA nodes have memory ranges that span

# other nodes.	Even though a pfn is valid and

arch/s390/include/asm/smp.h

+0 −5
Original line number Diff line number Diff line
@@ -53,14 +53,9 @@ static inline int smp_get_base_cpu(int cpu) 
	return cpu - (cpu % (smp_cpu_mtid + 1));

}



#ifdef CONFIG_HOTPLUG_CPU

extern int smp_rescan_cpus(void);

extern void __noreturn cpu_die(void);

extern void __cpu_die(unsigned int cpu);

extern int __cpu_disable(void);

#else

static inline int smp_rescan_cpus(void) { return 0; }

static inline void cpu_die(void) { }

#endif



#endif /* __ASM_SMP_H */

arch/s390/kernel/smp.c

+0 −19
Original line number Diff line number Diff line
@@ -232,8 +232,6 @@ out: 
	return -ENOMEM;

}



#ifdef CONFIG_HOTPLUG_CPU



static void pcpu_free_lowcore(struct pcpu *pcpu)

{

	unsigned long async_stack, nodat_stack, lowcore;
@@ -253,8 +251,6 @@ static void pcpu_free_lowcore(struct pcpu *pcpu) 
	free_pages(lowcore, LC_ORDER);

}



#endif /* CONFIG_HOTPLUG_CPU */



static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)

{

	struct lowcore *lc = pcpu->lowcore;
@@ -895,8 +891,6 @@ static int __init _setup_possible_cpus(char *s) 
}

early_param("possible_cpus", _setup_possible_cpus);



#ifdef CONFIG_HOTPLUG_CPU



int __cpu_disable(void)

{

	unsigned long cregs[16];
@@ -937,8 +931,6 @@ void __noreturn cpu_die(void) 
	for (;;) ;

}



#endif /* CONFIG_HOTPLUG_CPU */



void __init smp_fill_possible_mask(void)

{

	unsigned int possible, sclp_max, cpu;
@@ -996,7 +988,6 @@ int setup_profiling_timer(unsigned int multiplier) 
	return 0;

}



#ifdef CONFIG_HOTPLUG_CPU

static ssize_t cpu_configure_show(struct device *dev,

				  struct device_attribute *attr, char *buf)

{
@@ -1073,7 +1064,6 @@ out: 
	return rc ? rc : count;

}

static DEVICE_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);

#endif /* CONFIG_HOTPLUG_CPU */



static ssize_t show_cpu_address(struct device *dev,

				struct device_attribute *attr, char *buf)
@@ -1083,9 +1073,7 @@ static ssize_t show_cpu_address(struct device *dev, 
static DEVICE_ATTR(address, 0444, show_cpu_address, NULL);



static struct attribute *cpu_common_attrs[] = {

#ifdef CONFIG_HOTPLUG_CPU

	&dev_attr_configure.attr,

#endif

	&dev_attr_address.attr,

	NULL,

};
@@ -1144,15 +1132,11 @@ static int smp_add_present_cpu(int cpu) 
out_topology:

	sysfs_remove_group(&s->kobj, &cpu_common_attr_group);

out_cpu:

#ifdef CONFIG_HOTPLUG_CPU

	unregister_cpu(c);

#endif

out:

	return rc;

}



#ifdef CONFIG_HOTPLUG_CPU



int __ref smp_rescan_cpus(void)

{

	struct sclp_core_info *info;
@@ -1188,17 +1172,14 @@ static ssize_t __ref rescan_store(struct device *dev, 
	return rc ? rc : count;

}

static DEVICE_ATTR_WO(rescan);

#endif /* CONFIG_HOTPLUG_CPU */



static int __init s390_smp_init(void)

{

	int cpu, rc = 0;



#ifdef CONFIG_HOTPLUG_CPU

	rc = device_create_file(cpu_subsys.dev_root, &dev_attr_rescan);

	if (rc)

		return rc;

#endif

	for_each_present_cpu(cpu) {

		rc = smp_add_present_cpu(cpu);

		if (rc)

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