From: Will Deacon <will.deacon@arm.com>
Date: Mon, 6 Jun 2011 14:49:23 +0000 (+0100)
Subject: ARM: stop: execute platform callback from cpu_stop code
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=58825fd80e48bb0b823a42300361a3ce24a820fc;p=pandora-kernel.git

ARM: stop: execute platform callback from cpu_stop code

Sending IPI_CPU_STOP to a CPU causes it to execute a busy cpu_relax
loop forever. This makes it impossible to kexec successfully on an SMP
system since the secondary CPUs do not reset.

This patch adds a callback to platform_cpu_kill, defined when
CONFIG_HOTPLUG_CPU=y, from the ipi_cpu_stop handling code. This function
currently just returns 1 on all platforms that define it but allows them
to do something more sophisticated in the future.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c93ba0333bfc..c104153eb475 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -2017,7 +2017,7 @@ config XIP_PHYS_ADDR
 
 config KEXEC
 	bool "Kexec system call (EXPERIMENTAL)"
-	depends on EXPERIMENTAL
+	depends on EXPERIMENTAL && (!SMP || HOTPLUG_CPU)
 	help
 	  kexec is a system call that implements the ability to shutdown your
 	  current kernel, and to start another kernel.  It is like a reboot
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index a05ca124cbf1..250106df001b 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -526,6 +526,10 @@ static void ipi_cpu_stop(unsigned int cpu)
 	local_fiq_disable();
 	local_irq_disable();
 
+#ifdef CONFIG_HOTPLUG_CPU
+	platform_cpu_kill(cpu);
+#endif
+
 	while (1)
 		cpu_relax();
 }