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Diffstat (limited to 'arch/x86/kernel/smp.c')
-rw-r--r--arch/x86/kernel/smp.c100
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,