From 763ba1e4777b6be47c3d875e80ae9d9646500d7a Mon Sep 17 00:00:00 2001
From: Gautham R Shenoy <ego@in.ibm.com>
Date: Thu, 26 Nov 2009 09:59:05 +0000
Subject: [PATCH] --- yaml --- r: 175826 b: refs/heads/master c:
 51badebdcf394cc5fd574a524b55b3f6085e5e9c h: refs/heads/master v: v3

---
 [refs]                                       |  2 +-
 trunk/arch/powerpc/platforms/pseries/dlpar.c | 45 +++++++++++++++-----
 trunk/drivers/base/cpu.c                     |  2 +
 trunk/include/linux/cpu.h                    | 13 ++++++
 4 files changed, 51 insertions(+), 11 deletions(-)

diff --git a/[refs] b/[refs]
index 47a8910564be..139e49e6b893 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b6db63d1a7f0138f348ba7a648df35ac6365988e
+refs/heads/master: 51badebdcf394cc5fd574a524b55b3f6085e5e9c
diff --git a/trunk/arch/powerpc/platforms/pseries/dlpar.c b/trunk/arch/powerpc/platforms/pseries/dlpar.c
index 642e1b2e5c42..fd2f0afeb4de 100644
--- a/trunk/arch/powerpc/platforms/pseries/dlpar.c
+++ b/trunk/arch/powerpc/platforms/pseries/dlpar.c
@@ -436,6 +436,18 @@ int dlpar_release_drc(u32 drc_index)
 
 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 
+static DEFINE_MUTEX(pseries_cpu_hotplug_mutex);
+
+void cpu_hotplug_driver_lock()
+{
+	mutex_lock(&pseries_cpu_hotplug_mutex);
+}
+
+void cpu_hotplug_driver_unlock()
+{
+	mutex_unlock(&pseries_cpu_hotplug_mutex);
+}
+
 static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 {
 	struct device_node *dn;
@@ -443,13 +455,18 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 	char *cpu_name;
 	int rc;
 
+	cpu_hotplug_driver_lock();
 	rc = strict_strtoul(buf, 0, &drc_index);
-	if (rc)
-		return -EINVAL;
+	if (rc) {
+		rc = -EINVAL;
+		goto out;
+	}
 
 	dn = dlpar_configure_connector(drc_index);
-	if (!dn)
-		return -EINVAL;
+	if (!dn) {
+		rc = -EINVAL;
+		goto out;
+	}
 
 	/* configure-connector reports cpus as living in the base
 	 * directory of the device tree.  CPUs actually live in the
@@ -459,7 +476,8 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 			   GFP_KERNEL);
 	if (!cpu_name) {
 		dlpar_free_cc_nodes(dn);
-		return -ENOMEM;
+		rc = -ENOMEM;
+		goto out;
 	}
 
 	sprintf(cpu_name, "/cpus%s", dn->full_name);
@@ -469,7 +487,8 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 	rc = dlpar_acquire_drc(drc_index);
 	if (rc) {
 		dlpar_free_cc_nodes(dn);
-		return -EINVAL;
+		rc = -EINVAL;
+		goto out;
 	}
 
 	rc = dlpar_attach_node(dn);
@@ -479,6 +498,8 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 	}
 
 	rc = online_node_cpus(dn);
+out:
+	cpu_hotplug_driver_unlock();
 
 	return rc ? rc : count;
 }
@@ -499,26 +520,30 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t count)
 		return -EINVAL;
 	}
 
+	cpu_hotplug_driver_lock();
 	rc = offline_node_cpus(dn);
 	if (rc) {
 		of_node_put(dn);
-		return -EINVAL;
+		rc = -EINVAL;
+		goto out;
 	}
 
 	rc = dlpar_release_drc(*drc_index);
 	if (rc) {
 		of_node_put(dn);
-		return -EINVAL;
+		goto out;
 	}
 
 	rc = dlpar_detach_node(dn);
 	if (rc) {
 		dlpar_acquire_drc(*drc_index);
-		return rc;
+		goto out;
 	}
 
 	of_node_put(dn);
-	return count;
+out:
+	cpu_hotplug_driver_unlock();
+	return rc ? rc : count;
 }
 
 static int __init pseries_dlpar_init(void)
diff --git a/trunk/drivers/base/cpu.c b/trunk/drivers/base/cpu.c
index 7c03af7b84a9..27fd775375b0 100644
--- a/trunk/drivers/base/cpu.c
+++ b/trunk/drivers/base/cpu.c
@@ -35,6 +35,7 @@ static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribut
 	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
 	ssize_t ret;
 
+	cpu_hotplug_driver_lock();
 	switch (buf[0]) {
 	case '0':
 		ret = cpu_down(cpu->sysdev.id);
@@ -49,6 +50,7 @@ static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribut
 	default:
 		ret = -EINVAL;
 	}
+	cpu_hotplug_driver_unlock();
 
 	if (ret >= 0)
 		ret = count;
diff --git a/trunk/include/linux/cpu.h b/trunk/include/linux/cpu.h
index c972f7ccb7d3..e287863ac053 100644
--- a/trunk/include/linux/cpu.h
+++ b/trunk/include/linux/cpu.h
@@ -117,6 +117,19 @@ extern void put_online_cpus(void);
 #define unregister_hotcpu_notifier(nb)	unregister_cpu_notifier(nb)
 int cpu_down(unsigned int cpu);
 
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+extern void cpu_hotplug_driver_lock(void);
+extern void cpu_hotplug_driver_unlock(void);
+#else
+static inline void cpu_hotplug_driver_lock(void)
+{
+}
+
+static inline void cpu_hotplug_driver_unlock(void)
+{
+}
+#endif
+
 #else		/* CONFIG_HOTPLUG_CPU */
 
 #define get_online_cpus()	do { } while (0)