smp: Add generic smpboot facility

Start a new file, which will hold SMP and CPU hotplug related generic
infrastructure.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20120420124557.035417523@linutronix.de

4 files changed, 29 insertions, 0 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index cb41b9547c9f..6c07f30fa9b7 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
 obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
 obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
 obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_SMP) += smpboot.o
 ifneq ($(CONFIG_SMP),y)
 obj-y += up.o
 endif
diff --git a/kernel/cpu.c b/kernel/cpu.c
index e711aef0fb3c..e58b99ada3d8 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -17,6 +17,8 @@
 #include <linux/gfp.h>
 #include <linux/suspend.h>
 
+#include "smpboot.h"
+
 #ifdef CONFIG_SMP
 /* Serializes the updates to cpu_online_mask, cpu_present_mask */
 static DEFINE_MUTEX(cpu_add_remove_lock);
@@ -300,6 +302,11 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
                 return -EINVAL;
 
         cpu_hotplug_begin();
+
+        ret = smpboot_prepare(cpu);
+        if (ret)
+                goto out;
+
         ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
         if (ret) {
                 nr_calls--;
@@ -320,6 +327,7 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
 out_notify:
         if (ret != 0)
                 __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
+out:
         cpu_hotplug_done();
 
         return ret;
diff --git a/kernel/smpboot.c b/kernel/smpboot.c
new file mode 100644
index 000000000000..6dae6a3d2d59
--- /dev/null
+++ b/kernel/smpboot.c
@@ -0,0 +1,14 @@
+/*
+ * Common SMP CPU bringup/teardown functions
+ */
+#include <linux/init.h>
+
+#include "smpboot.h"
+
+/**
+ * smpboot_prepare - generic smpboot preparation
+ */
+int __cpuinit smpboot_prepare(unsigned int cpu)
+{
+        return 0;
+}
diff --git a/kernel/smpboot.h b/kernel/smpboot.h
new file mode 100644
index 000000000000..d88e77165086
--- /dev/null
+++ b/kernel/smpboot.h
@@ -0,0 +1,6 @@
+#ifndef SMPBOOT_H
+#define SMPBOOT_H
+
+int smpboot_prepare(unsigned int cpu);
+
+#endif