Re: [PATCH v2] parisc: Add raise_nmi() and arch_trigger_cpumask_backtrace()

[Helge Deller <deller@xxxxxx>]

Implement the parisc versions for raise_nmi() and arch_trigger_cpumask_backtrace()
functions to provide IPI-triggered per-CPU backtrace printouts.

Signed-off-by: Helge Deller <deller@xxxxxx>

diff --git a/arch/parisc/include/asm/irq.h b/arch/parisc/include/asm/irq.h
index 959e79cd2c14..c978d50bd29e 100644
--- a/arch/parisc/include/asm/irq.h
+++ b/arch/parisc/include/asm/irq.h
@@ -50,4 +50,10 @@ extern int cpu_check_affinity(struct irq_data *d, const struct cpumask *dest);
 /* soft power switch support (power.c) */
 extern struct tasklet_struct power_tasklet;

+#ifdef CONFIG_SMP
+extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
+					   bool exclude_self);
+#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
+#endif
+
 #endif	/* _ASM_PARISC_IRQ_H */
diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
index 6271139d2213..cd7694497428 100644
--- a/arch/parisc/kernel/smp.c
+++ b/arch/parisc/kernel/smp.c
@@ -29,6 +29,7 @@
 #include <linux/bitops.h>
 #include <linux/ftrace.h>
 #include <linux/cpu.h>
+#include <linux/nmi.h>

 #include <linux/atomic.h>
 #include <asm/current.h>
@@ -69,6 +70,7 @@ enum ipi_message_type {
 	IPI_CALL_FUNC,
 	IPI_CPU_START,
 	IPI_CPU_STOP,
+	IPI_CPU_BACKTRACE,
 	IPI_CPU_TEST
 };

@@ -164,6 +166,14 @@ ipi_interrupt(int irq, void *dev_id)
 				halt_processor();
 				break;

+			case IPI_CPU_BACKTRACE:
+				printk_nmi_enter();
+				irq_enter();
+				nmi_cpu_backtrace(get_irq_regs());
+				irq_exit();
+				printk_nmi_exit();
+				break;
+
 			case IPI_CPU_TEST:
 				smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
 				break;
@@ -173,9 +183,12 @@ ipi_interrupt(int irq, void *dev_id)
 					this_cpu, which);
 				return IRQ_NONE;
 			} /* Switch */
-		/* let in any pending interrupts */
-		local_irq_enable();
-		local_irq_disable();
+
+			/* before doing more, let in any pending interrupts */
+			if (ops) {
+				local_irq_enable();
+				local_irq_disable();
+			}
 		} /* while (ops) */
 	}
 	return IRQ_HANDLED;
@@ -246,6 +259,16 @@ void arch_send_call_function_single_ipi(int cpu)
 	send_IPI_single(cpu, IPI_CALL_FUNC);
 }

+static void raise_nmi(cpumask_t *mask)
+{
+	send_IPI_mask(mask, IPI_CPU_BACKTRACE);
+}
+
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+{
+	nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
+}
+
 /*
  * Called by secondaries to update state and initialize CPU registers.
  */