Commit d80512f8 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

s390/smp: improve setup of possible cpu mask 



Since under z/VM we cannot have more than 64 cpus, make sure the
cpu_possible_mask does not contain more bits.
This avoids wasting memory for dynamic per-cpu allocations if
CONFIG_NR_CPUS is larger than 64.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 319e2e3f

arch/s390/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -135,7 +135,6 @@ config S390 
	select HAVE_SYSCALL_TRACEPOINTS

	select HAVE_UID16 if 32BIT

	select HAVE_VIRT_CPU_ACCOUNTING

	select INIT_ALL_POSSIBLE

	select KTIME_SCALAR if 32BIT

	select MODULES_USE_ELF_RELA

	select OLD_SIGACTION

arch/s390/include/asm/smp.h

+2 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ extern void smp_yield(void); 
extern void smp_stop_cpu(void);

extern void smp_cpu_set_polarization(int cpu, int val);

extern int smp_cpu_get_polarization(int cpu);

extern void smp_fill_possible_mask(void);



#else /* CONFIG_SMP */
@@ -50,6 +51,7 @@ static inline int smp_vcpu_scheduled(int cpu) { return 1; } 
static inline void smp_yield_cpu(int cpu) { }

static inline void smp_yield(void) { }

static inline void smp_stop_cpu(void) { }

static inline void smp_fill_possible_mask(void) { }



#endif /* CONFIG_SMP */

arch/s390/kernel/setup.c

+1 −0
Original line number Diff line number Diff line
@@ -1023,6 +1023,7 @@ void __init setup_arch(char **cmdline_p) 
	setup_vmcoreinfo();

	setup_lowcore();



	smp_fill_possible_mask();

        cpu_init();

	s390_init_cpu_topology();

arch/s390/kernel/smp.c

+16 −9
Original line number Diff line number Diff line
@@ -721,18 +721,14 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle) 
	return 0;

}



static int __init setup_possible_cpus(char *s)

{

	int max, cpu;

static unsigned int setup_possible_cpus __initdata;



	if (kstrtoint(s, 0, &max) < 0)

		return 0;

	init_cpu_possible(cpumask_of(0));

	for (cpu = 1; cpu < max && cpu < nr_cpu_ids; cpu++)

		set_cpu_possible(cpu, true);

static int __init _setup_possible_cpus(char *s)

{

	get_option(&s, &setup_possible_cpus);

	return 0;

}

early_param("possible_cpus", setup_possible_cpus);

early_param("possible_cpus", _setup_possible_cpus);



#ifdef CONFIG_HOTPLUG_CPU
@@ -775,6 +771,17 @@ void __noreturn cpu_die(void) 


#endif /* CONFIG_HOTPLUG_CPU */



void __init smp_fill_possible_mask(void)

{

	unsigned int possible, cpu;



	possible = setup_possible_cpus;

	if (!possible)

		possible = MACHINE_IS_VM ? 64 : nr_cpu_ids;

	for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)

		set_cpu_possible(cpu, true);

}



void __init smp_prepare_cpus(unsigned int max_cpus)

{

	/* request the 0x1201 emergency signal external interrupt */

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