diff options
| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2011-09-19 19:44:49 +0200 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2011-09-20 07:53:24 +0200 |
| commit | fb82b83970a32263698e54a8779d2ce88cd3b060 (patch) | |
| tree | 3f396a3225fa7eae960d9033926b00e751327577 | |
| parent | powerpc/udbg: Fix Kconfig entry for avoiding 44x early debug with KVM (diff) | |
| download | linux-fb82b83970a32263698e54a8779d2ce88cd3b060.tar.xz linux-fb82b83970a32263698e54a8779d2ce88cd3b060.zip | |
powerpc/smp: More generic support for "soft hotplug"
This adds more generic support for doing CPU hotplug with a simple
idle loop and no actual reset of the processors. The generic
smp_generic_kick_cpu() does the hotplug bringup trick if the PACA
shows that the CPU has already been started at boot and we provide
an accessor for the CPU state.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
| -rw-r--r-- | arch/powerpc/include/asm/smp.h | 1 | ||||
| -rw-r--r-- | arch/powerpc/kernel/smp.c | 30 |
2 files changed, 26 insertions, 5 deletions
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h index 15a70b7f638b..adba970ce918 100644 --- a/arch/powerpc/include/asm/smp.h +++ b/arch/powerpc/include/asm/smp.h @@ -65,6 +65,7 @@ int generic_cpu_disable(void); void generic_cpu_die(unsigned int cpu); void generic_mach_cpu_die(void); void generic_set_cpu_dead(unsigned int cpu); +int generic_check_cpu_restart(unsigned int cpu); #endif #ifdef CONFIG_PPC64 diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 7bf2187dfd99..af7e7722ecae 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -70,6 +70,10 @@ static DEFINE_PER_CPU(struct task_struct *, idle_thread_array); #define get_idle_for_cpu(x) (per_cpu(idle_thread_array, x)) #define set_idle_for_cpu(x, p) (per_cpu(idle_thread_array, x) = (p)) + +/* State of each CPU during hotplug phases */ +static DEFINE_PER_CPU(int, cpu_state) = { 0 }; + #else static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ; #define get_idle_for_cpu(x) (idle_thread_array[(x)]) @@ -104,12 +108,25 @@ int __devinit smp_generic_kick_cpu(int nr) * cpu_start field to become non-zero After we set cpu_start, * the processor will continue on to secondary_start */ - paca[nr].cpu_start = 1; - smp_mb(); + if (!paca[nr].cpu_start) { + paca[nr].cpu_start = 1; + smp_mb(); + return 0; + } + +#ifdef CONFIG_HOTPLUG_CPU + /* + * Ok it's not there, so it might be soft-unplugged, let's + * try to bring it back + */ + per_cpu(cpu_state, nr) = CPU_UP_PREPARE; + smp_wmb(); + smp_send_reschedule(nr); +#endif /* CONFIG_HOTPLUG_CPU */ return 0; } -#endif +#endif /* CONFIG_PPC64 */ static irqreturn_t call_function_action(int irq, void *data) { @@ -357,8 +374,6 @@ void __devinit smp_prepare_boot_cpu(void) } #ifdef CONFIG_HOTPLUG_CPU -/* State of each CPU during hotplug phases */ -static DEFINE_PER_CPU(int, cpu_state) = { 0 }; int generic_cpu_disable(void) { @@ -406,6 +421,11 @@ void generic_set_cpu_dead(unsigned int cpu) { per_cpu(cpu_state, cpu) = CPU_DEAD; } + +int generic_check_cpu_restart(unsigned int cpu) +{ + return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE; +} #endif struct create_idle { |