diff options
Diffstat (limited to 'arch/x86/kernel/smp.c')
| -rw-r--r-- | arch/x86/kernel/smp.c | 100 |
1 files changed, 46 insertions, 54 deletions
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index 66c74f481ca..48d2b7ded42 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -109,6 +109,9 @@ * about nothing of note with C stepping upwards. */ +static atomic_t stopping_cpu = ATOMIC_INIT(-1); +static bool smp_no_nmi_ipi = false; + /* * this function sends a 'reschedule' IPI to another CPU. * it goes straight through and wastes no time serializing @@ -149,8 +152,6 @@ void native_send_call_func_ipi(const struct cpumask *mask) free_cpumask_var(allbutself); } -static atomic_t stopping_cpu = ATOMIC_INIT(-1); - static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs) { /* We are registered on stopping cpu too, avoid spurious NMI */ @@ -162,7 +163,19 @@ static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs) return NMI_HANDLED; } -static void native_nmi_stop_other_cpus(int wait) +/* + * this function calls the 'stop' function on all other CPUs in the system. + */ + +asmlinkage void smp_reboot_interrupt(void) +{ + ack_APIC_irq(); + irq_enter(); + stop_this_cpu(NULL); + irq_exit(); +} + +static void native_stop_other_cpus(int wait) { unsigned long flags; unsigned long timeout; @@ -174,20 +187,25 @@ static void native_nmi_stop_other_cpus(int wait) * Use an own vector here because smp_call_function * does lots of things not suitable in a panic situation. */ + + /* + * We start by using the REBOOT_VECTOR irq. + * The irq is treated as a sync point to allow critical + * regions of code on other cpus to release their spin locks + * and re-enable irqs. Jumping straight to an NMI might + * accidentally cause deadlocks with further shutdown/panic + * code. By syncing, we give the cpus up to one second to + * finish their work before we force them off with the NMI. + */ if (num_online_cpus() > 1) { /* did someone beat us here? */ if (atomic_cmpxchg(&stopping_cpu, -1, safe_smp_processor_id()) != -1) return; - if (register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback, - NMI_FLAG_FIRST, "smp_stop")) - /* Note: we ignore failures here */ - return; - - /* sync above data before sending NMI */ + /* sync above data before sending IRQ */ wmb(); - apic->send_IPI_allbutself(NMI_VECTOR); + apic->send_IPI_allbutself(REBOOT_VECTOR); /* * Don't wait longer than a second if the caller @@ -197,63 +215,37 @@ static void native_nmi_stop_other_cpus(int wait) while (num_online_cpus() > 1 && (wait || timeout--)) udelay(1); } + + /* if the REBOOT_VECTOR didn't work, try with the NMI */ + if ((num_online_cpus() > 1) && (!smp_no_nmi_ipi)) { + if (register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback, + NMI_FLAG_FIRST, "smp_stop")) + /* Note: we ignore failures here */ + /* Hope the REBOOT_IRQ is good enough */ + goto finish; - local_irq_save(flags); - disable_local_APIC(); - local_irq_restore(flags); -} - -/* - * this function calls the 'stop' function on all other CPUs in the system. - */ - -asmlinkage void smp_reboot_interrupt(void) -{ - ack_APIC_irq(); - irq_enter(); - stop_this_cpu(NULL); - irq_exit(); -} - -static void native_irq_stop_other_cpus(int wait) -{ - unsigned long flags; - unsigned long timeout; + /* sync above data before sending IRQ */ + wmb(); - if (reboot_force) - return; + pr_emerg("Shutting down cpus with NMI\n"); - /* - * Use an own vector here because smp_call_function - * does lots of things not suitable in a panic situation. - * On most systems we could also use an NMI here, - * but there are a few systems around where NMI - * is problematic so stay with an non NMI for now - * (this implies we cannot stop CPUs spinning with irq off - * currently) - */ - if (num_online_cpus() > 1) { - apic->send_IPI_allbutself(REBOOT_VECTOR); + apic->send_IPI_allbutself(NMI_VECTOR); /* - * Don't wait longer than a second if the caller + * Don't wait longer than a 10 ms if the caller * didn't ask us to wait. */ - timeout = USEC_PER_SEC; + timeout = USEC_PER_MSEC * 10; while (num_online_cpus() > 1 && (wait || timeout--)) udelay(1); } +finish: local_irq_save(flags); disable_local_APIC(); local_irq_restore(flags); } -static void native_smp_disable_nmi_ipi(void) -{ - smp_ops.stop_other_cpus = native_irq_stop_other_cpus; -} - /* * Reschedule call back. */ @@ -287,8 +279,8 @@ void smp_call_function_single_interrupt(struct pt_regs *regs) static int __init nonmi_ipi_setup(char *str) { - native_smp_disable_nmi_ipi(); - return 1; + smp_no_nmi_ipi = true; + return 1; } __setup("nonmi_ipi", nonmi_ipi_setup); @@ -298,7 +290,7 @@ struct smp_ops smp_ops = { .smp_prepare_cpus = native_smp_prepare_cpus, .smp_cpus_done = native_smp_cpus_done, - .stop_other_cpus = native_nmi_stop_other_cpus, + .stop_other_cpus = native_stop_other_cpus, .smp_send_reschedule = native_smp_send_reschedule, .cpu_up = native_cpu_up, |