[PATCH v21 3/8] arm64: kdump: implement machine_crash_shutdown()

On Wed, Jul 06, 2016 at 10:28:57AM -0700, Geoff Levand wrote:

On Wed, 2016-07-06 at 16:52 +0900, AKASHI Takahiro wrote:

quoted

--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h

@@ -136,6 +136,10 @@ static inline void cpu_panic_kernel(void)
  */
 bool cpus_are_stuck_in_kernel(void);
 
+#ifdef CONFIG_KEXEC_CORE
+extern void smp_send_crash_stop(void);
+#endif

It seems this could be simplified by removing these
conditionals, then move the conditionals that are
around the smp_send_crash_stop definition to inside
that definition.

OK.

quoted

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 62ff3c0..51e0b73 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c

@@ -800,6 +803,28 @@ static void ipi_cpu_stop(unsigned int cpu)
 > 	> 	> cpu_relax();
 }
 
+#ifdef CONFIG_KEXEC_CORE
+static atomic_t waiting_for_crash_ipi;
+
+static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
+{
+> 	> crash_save_cpu(regs, cpu);
+
+> 	> atomic_dec(&waiting_for_crash_ipi);
+
+> 	> local_irq_disable();
+
+#ifdef CONFIG_HOTPLUG_CPU
+> 	> if (cpu_ops[cpu]->cpu_die)
+> 	> 	> cpu_ops[cpu]->cpu_die(cpu);
+#endif
+
+> 	> /* just in case */
+> 	> while (1)
+> 	> 	> wfi();
+}
+#endif

 /*

quoted

  * Main handler for inter-processor interrupts
  */

@@ -830,6 +855,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 > 	> 	> irq_exit();
 > 	> 	> break;
 
+#ifdef CONFIG_KEXEC_CORE
+> 	> case IPI_CPU_CRASH_STOP:
+> 	> 	> irq_enter();
+> 	> 	> ipi_cpu_crash_stop(cpu, regs);
+
+> 	> 	> unreachable();
+#endif

It seems like you could simplifiy with something like:

	case IPI_CPU_CRASH_STOP:
		if (IS_ENABLED(CONFIG_KEXEC_CORE) {
			irq_enter();
			ipi_cpu_crash_stop(cpu, regs);
			unreachable();
		}

OK, I will take this.

Then move the CONFIG_KEXEC_CORE conditional around
ipi_cpu_crash_stop to just around crash_save_cpu().

Yeah, we can do that, but I added these conditionals just because
the kernel size can be reduced (a bit, obviously) if kexec is
not needed.
So instead of removing the conditional around ipi_cpu_crash_stop(),
an empty definition will be added for !CONFIG_KEXEC_CORE.

Thanks,
-Takahiro AKASHI

 -Geoff