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: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 1e1a03d..e9f3125 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -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

diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h
index ac9bed8..1607793 100644 (file)
--- a/arch/s390/include/asm/smp.h
+++ b/arch/s390/include/asm/smp.h
@@ -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 */
 

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 4444875..0f3d44e 100644 (file)
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -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();
 

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index dc4a534..9587047 100644 (file)
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -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 */