[patch 0/9] CPU hotplug error handling fixes take2

[patch 0/9] CPU hotplug error handling fixes take2

[Akinobu Mita]

This series of patches fixes the error handling for cpu hotplug.
The problem is revealed by CPU hotplug/unplug test with fault-injection.

The changes from previous patchset:

- Removed the patch titled sysfs: avoid kmem_cache_free(NULL)
  Because it was merged into mainline.

- Removed the patch titled sysdev: add error check in sysdev_register()
  It turned out that the patch needs more fixes for microcode and
  cpufreq. So I'll separate them from this series of patches.

- Added slab fix noticed by Gautham R Shenoy

The series of patches:

[patch 1/9] slab: cleanup cpuup_callback()
[patch 2/9] slab: fix memory leak in cpu hotplug error path
[patch 3/9] cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks
            with CPU_UP_PREPARE
[patch 4/9] topology: remove topology_dev_map
[patch 5/9] thermal_throttle: fix cpu hotplug error handling
[patch 6/9] msr: fix cpu hotplug error handling
[patch 7/9] cpuid: fix cpu hotplug error handling
[patch 8/9] mce: fix cpu hotplug error handling
[patch 9/9] intel_cacheinfo: fix cpu hotplug error handling

The patch 1/9 factors out some code from cpuup_callback() to simplify
what the patch 2/9 does.

The patch 2/9 fixes memory leak in allocation failure path. Also it
avoids the memory leak that will be introduced by the patch 3/9.

The patch 3/9 changes the behavior when one of the callbacks in notifier
chain returns NOTIFY_BAD with CPU_UP_PREPARE event. This change makes
cpu hotplug error handling simple.

The patch 4/9 simplifies the cpu hotplug event handling in topology.c
enabled by the patch 3/9.

The patch 5-9/9 are cpu hotplug error handling fixes in drivers.
Mainly these patches shift some callbacks from CPU_ONLINE to CPU_UP_PREPARE.

CPU hotplug/unplug test script:

----------[ cut here ]----------

#!/bin/bash

FAILTYPE=failslab
CPU=1
CPU_ONLINE=/sys/devices/system/cpu/cpu${CPU}/online

faulty_system()
{
	bash -c "echo 1 > /proc/self/make-it-fail && exec $*"
}

[ "$UID" == 0 ] || exit 1
[ -n "$FAILTYPE" -a -f /debug/$FAILTYPE/probability ] || exit 1
[ -f $CPU_ONLINE ] || exit 1

echo N > /debug/$FAILTYPE/ignore-gfp-wait
echo Y > /debug/$FAILTYPE/task-filter
echo 1 > /debug/$FAILTYPE/probability
echo -1 > /debug/$FAILTYPE/times

while true
do
	faulty_system "echo 0 > $CPU_ONLINE"
	faulty_system "echo 1 > $CPU_ONLINE"
done

[patch 1/9] slab: cleanup cpuup_callback()

[Akinobu Mita]

[-- Attachment #1: slab-refactor.patch --]
[-- Type: text/plain, Size: 9309 bytes --]

cpuup_callback() is too long.
This patch factors out CPU_UP_CANCELLED and CPU_UP_PREPARE handlings
from cpuup_callback().

Cc: Christoph Lameter <clameter@sgi.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 mm/slab.c |  301 ++++++++++++++++++++++++++++++++------------------------------
 1 file changed, 159 insertions(+), 142 deletions(-)

Index: 2.6-git/mm/slab.c
===================================================================
--- 2.6-git.orig/mm/slab.c
+++ 2.6-git/mm/slab.c
@@ -1156,105 +1156,181 @@ static inline int cache_free_alien(struc
 }
 #endif
 
-static int __cpuinit cpuup_callback(struct notifier_block *nfb,
-				    unsigned long action, void *hcpu)
+static void __cpuinit cpuup_canceled(long cpu)
+{
+	struct kmem_cache *cachep;
+	struct kmem_list3 *l3 = NULL;
+	int node = cpu_to_node(cpu);
+
+	list_for_each_entry(cachep, &cache_chain, next) {
+		struct array_cache *nc;
+		struct array_cache *shared;
+		struct array_cache **alien;
+		cpumask_t mask;
+
+		mask = node_to_cpumask(node);
+		/* cpu is dead; no one can alloc from it. */
+		nc = cachep->array[cpu];
+		cachep->array[cpu] = NULL;
+		l3 = cachep->nodelists[node];
+
+		if (!l3)
+			goto free_array_cache;
+
+		spin_lock_irq(&l3->list_lock);
+
+		/* Free limit for this kmem_list3 */
+		l3->free_limit -= cachep->batchcount;
+		if (nc)
+			free_block(cachep, nc->entry, nc->avail, node);
+
+		if (!cpus_empty(mask)) {
+			spin_unlock_irq(&l3->list_lock);
+			goto free_array_cache;
+		}
+
+		shared = l3->shared;
+		if (shared) {
+			free_block(cachep, shared->entry,
+				   shared->avail, node);
+			l3->shared = NULL;
+		}
+
+		alien = l3->alien;
+		l3->alien = NULL;
+
+		spin_unlock_irq(&l3->list_lock);
+
+		kfree(shared);
+		if (alien) {
+			drain_alien_cache(cachep, alien);
+			free_alien_cache(alien);
+		}
+free_array_cache:
+		kfree(nc);
+	}
+	/*
+	 * In the previous loop, all the objects were freed to
+	 * the respective cache's slabs,  now we can go ahead and
+	 * shrink each nodelist to its limit.
+	 */
+	list_for_each_entry(cachep, &cache_chain, next) {
+		l3 = cachep->nodelists[node];
+		if (!l3)
+			continue;
+		drain_freelist(cachep, l3, l3->free_objects);
+	}
+}
+
+static int __cpuinit cpuup_prepare(long cpu)
 {
-	long cpu = (long)hcpu;
 	struct kmem_cache *cachep;
 	struct kmem_list3 *l3 = NULL;
 	int node = cpu_to_node(cpu);
 	const int memsize = sizeof(struct kmem_list3);
 
-	switch (action) {
-	case CPU_LOCK_ACQUIRE:
-		mutex_lock(&cache_chain_mutex);
-		break;
-	case CPU_UP_PREPARE:
-	case CPU_UP_PREPARE_FROZEN:
+	/*
+	 * We need to do this right in the beginning since
+	 * alloc_arraycache's are going to use this list.
+	 * kmalloc_node allows us to add the slab to the right
+	 * kmem_list3 and not this cpu's kmem_list3
+	 */
+
+	list_for_each_entry(cachep, &cache_chain, next) {
 		/*
-		 * We need to do this right in the beginning since
-		 * alloc_arraycache's are going to use this list.
-		 * kmalloc_node allows us to add the slab to the right
-		 * kmem_list3 and not this cpu's kmem_list3
+		 * Set up the size64 kmemlist for cpu before we can
+		 * begin anything. Make sure some other cpu on this
+		 * node has not already allocated this
 		 */
+		if (!cachep->nodelists[node]) {
+			l3 = kmalloc_node(memsize, GFP_KERNEL, node);
+			if (!l3)
+				goto bad;
+			kmem_list3_init(l3);
+			l3->next_reap = jiffies + REAPTIMEOUT_LIST3 +
+			    ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
 
-		list_for_each_entry(cachep, &cache_chain, next) {
 			/*
-			 * Set up the size64 kmemlist for cpu before we can
-			 * begin anything. Make sure some other cpu on this
-			 * node has not already allocated this
+			 * The l3s don't come and go as CPUs come and
+			 * go.  cache_chain_mutex is sufficient
+			 * protection here.
 			 */
-			if (!cachep->nodelists[node]) {
-				l3 = kmalloc_node(memsize, GFP_KERNEL, node);
-				if (!l3)
-					goto bad;
-				kmem_list3_init(l3);
-				l3->next_reap = jiffies + REAPTIMEOUT_LIST3 +
-				    ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
-
-				/*
-				 * The l3s don't come and go as CPUs come and
-				 * go.  cache_chain_mutex is sufficient
-				 * protection here.
-				 */
-				cachep->nodelists[node] = l3;
-			}
-
-			spin_lock_irq(&cachep->nodelists[node]->list_lock);
-			cachep->nodelists[node]->free_limit =
-				(1 + nr_cpus_node(node)) *
-				cachep->batchcount + cachep->num;
-			spin_unlock_irq(&cachep->nodelists[node]->list_lock);
+			cachep->nodelists[node] = l3;
 		}
 
-		/*
-		 * Now we can go ahead with allocating the shared arrays and
-		 * array caches
-		 */
-		list_for_each_entry(cachep, &cache_chain, next) {
-			struct array_cache *nc;
-			struct array_cache *shared = NULL;
-			struct array_cache **alien = NULL;
+		spin_lock_irq(&cachep->nodelists[node]->list_lock);
+		cachep->nodelists[node]->free_limit =
+			(1 + nr_cpus_node(node)) *
+			cachep->batchcount + cachep->num;
+		spin_unlock_irq(&cachep->nodelists[node]->list_lock);
+	}
 
-			nc = alloc_arraycache(node, cachep->limit,
-						cachep->batchcount);
-			if (!nc)
+	/*
+	 * Now we can go ahead with allocating the shared arrays and
+	 * array caches
+	 */
+	list_for_each_entry(cachep, &cache_chain, next) {
+		struct array_cache *nc;
+		struct array_cache *shared = NULL;
+		struct array_cache **alien = NULL;
+
+		nc = alloc_arraycache(node, cachep->limit,
+					cachep->batchcount);
+		if (!nc)
+			goto bad;
+		if (cachep->shared) {
+			shared = alloc_arraycache(node,
+				cachep->shared * cachep->batchcount,
+				0xbaadf00d);
+			if (!shared)
 				goto bad;
-			if (cachep->shared) {
-				shared = alloc_arraycache(node,
-					cachep->shared * cachep->batchcount,
-					0xbaadf00d);
-				if (!shared)
-					goto bad;
-			}
-			if (use_alien_caches) {
-                                alien = alloc_alien_cache(node, cachep->limit);
-                                if (!alien)
-                                        goto bad;
-                        }
-			cachep->array[cpu] = nc;
-			l3 = cachep->nodelists[node];
-			BUG_ON(!l3);
+		}
+		if (use_alien_caches) {
+			alien = alloc_alien_cache(node, cachep->limit);
+			if (!alien)
+				goto bad;
+		}
+		cachep->array[cpu] = nc;
+		l3 = cachep->nodelists[node];
+		BUG_ON(!l3);
 
-			spin_lock_irq(&l3->list_lock);
-			if (!l3->shared) {
-				/*
-				 * We are serialised from CPU_DEAD or
-				 * CPU_UP_CANCELLED by the cpucontrol lock
-				 */
-				l3->shared = shared;
-				shared = NULL;
-			}
+		spin_lock_irq(&l3->list_lock);
+		if (!l3->shared) {
+			/*
+			 * We are serialised from CPU_DEAD or
+			 * CPU_UP_CANCELLED by the cpucontrol lock
+			 */
+			l3->shared = shared;
+			shared = NULL;
+		}
 #ifdef CONFIG_NUMA
-			if (!l3->alien) {
-				l3->alien = alien;
-				alien = NULL;
-			}
-#endif
-			spin_unlock_irq(&l3->list_lock);
-			kfree(shared);
-			free_alien_cache(alien);
+		if (!l3->alien) {
+			l3->alien = alien;
+			alien = NULL;
 		}
+#endif
+		spin_unlock_irq(&l3->list_lock);
+		kfree(shared);
+		free_alien_cache(alien);
+	}
+	return 0;
+bad:
+	return -ENOMEM;
+}
+
+static int __cpuinit cpuup_callback(struct notifier_block *nfb,
+				    unsigned long action, void *hcpu)
+{
+	long cpu = (long)hcpu;
+	int err = 0;
+
+	switch (action) {
+	case CPU_LOCK_ACQUIRE:
+		mutex_lock(&cache_chain_mutex);
+		break;
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		err = cpuup_prepare(cpu);
 		break;
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
@@ -1291,72 +1367,13 @@ static int __cpuinit cpuup_callback(stru
 #endif
 	case CPU_UP_CANCELED:
 	case CPU_UP_CANCELED_FROZEN:
-		list_for_each_entry(cachep, &cache_chain, next) {
-			struct array_cache *nc;
-			struct array_cache *shared;
-			struct array_cache **alien;
-			cpumask_t mask;
-
-			mask = node_to_cpumask(node);
-			/* cpu is dead; no one can alloc from it. */
-			nc = cachep->array[cpu];
-			cachep->array[cpu] = NULL;
-			l3 = cachep->nodelists[node];
-
-			if (!l3)
-				goto free_array_cache;
-
-			spin_lock_irq(&l3->list_lock);
-
-			/* Free limit for this kmem_list3 */
-			l3->free_limit -= cachep->batchcount;
-			if (nc)
-				free_block(cachep, nc->entry, nc->avail, node);
-
-			if (!cpus_empty(mask)) {
-				spin_unlock_irq(&l3->list_lock);
-				goto free_array_cache;
-			}
-
-			shared = l3->shared;
-			if (shared) {
-				free_block(cachep, shared->entry,
-					   shared->avail, node);
-				l3->shared = NULL;
-			}
-
-			alien = l3->alien;
-			l3->alien = NULL;
-
-			spin_unlock_irq(&l3->list_lock);
-
-			kfree(shared);
-			if (alien) {
-				drain_alien_cache(cachep, alien);
-				free_alien_cache(alien);
-			}
-free_array_cache:
-			kfree(nc);
-		}
-		/*
-		 * In the previous loop, all the objects were freed to
-		 * the respective cache's slabs,  now we can go ahead and
-		 * shrink each nodelist to its limit.
-		 */
-		list_for_each_entry(cachep, &cache_chain, next) {
-			l3 = cachep->nodelists[node];
-			if (!l3)
-				continue;
-			drain_freelist(cachep, l3, l3->free_objects);
-		}
+		cpuup_canceled(cpu);
 		break;
 	case CPU_LOCK_RELEASE:
 		mutex_unlock(&cache_chain_mutex);
 		break;
 	}
-	return NOTIFY_OK;
-bad:
-	return NOTIFY_BAD;
+	return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
 static struct notifier_block __cpuinitdata cpucache_notifier = {

-- 

[patch 2/9] slab: fix memory leak in cpu hotplug error path

[Akinobu Mita]

[-- Attachment #1: slab-cpuhotplug-memleak-fixes.patch --]
[-- Type: text/plain, Size: 1179 bytes --]

This patch fixes memory leak in error path.

In reality, we don't need to call cpuup_canceled(cpu) for now.
But upcoming cpu hotplug error handling change needs this.

Cc: Christoph Lameter <clameter@sgi.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 mm/slab.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Index: 2.6-git/mm/slab.c
===================================================================
--- 2.6-git.orig/mm/slab.c
+++ 2.6-git/mm/slab.c
@@ -1282,13 +1282,18 @@ static int __cpuinit cpuup_prepare(long 
 			shared = alloc_arraycache(node,
 				cachep->shared * cachep->batchcount,
 				0xbaadf00d);
-			if (!shared)
+			if (!shared) {
+				kfree(nc);
 				goto bad;
+			}
 		}
 		if (use_alien_caches) {
 			alien = alloc_alien_cache(node, cachep->limit);
-			if (!alien)
+			if (!alien) {
+				kfree(shared);
+				kfree(nc);
 				goto bad;
+			}
 		}
 		cachep->array[cpu] = nc;
 		l3 = cachep->nodelists[node];
@@ -1315,6 +1320,7 @@ static int __cpuinit cpuup_prepare(long 
 	}
 	return 0;
 bad:
+	cpuup_canceled(cpu);
 	return -ENOMEM;
 }
 

-- 

[patch 3/9] cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE

[Akinobu Mita]

[-- Attachment #1: cpuhotplug-nr-calls.patch --]
[-- Type: text/plain, Size: 2349 bytes --]

From: Akinobu Mita <akinobu.mita@gmail.com>

The functions in a CPU notifier chain is called with CPU_UP_PREPARE event
before making the CPU online. If one of the callback returns NOTIFY_BAD,
it stops to deliver CPU_UP_PREPARE event, and CPU online operation is canceled.
Then CPU_UP_CANCELED event is delivered to the functions in a CPU notifier
chain again.

This CPU_UP_CANCELED event is delivered to the functions which have been
called with CPU_UP_PREPARE, not delivered to the functions which haven't
been called with CPU_UP_PREPARE.

The problem that makes existing cpu hotplug error handlings complex is
that the CPU_UP_CANCELED event is delivered to the function that has
returned NOTIFY_BAD, too.

Usually we don't expect to call destructor function against the
object that has failed to initialize. It is like:

	err = register_something();
	if (err) {
		unregister_something();
		return err;
	}

So it is natural to deliver CPU_UP_CANCELED event only to the functions
that have returned NOTIFY_OK with CPU_UP_PREPARE event and not to call
the function that have returned NOTIFY_BAD. This is what this patch is doing.

Otherwise, every cpu hotplug notifiler has to track whether
notifiler event is failed or not for each cpu.
(drivers/base/topology.c is doing this with topology_dev_map)

Similary this patch makes same thing with CPU_DOWN_PREPARE and
CPU_DOWN_FAILED evnets.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 kernel/cpu.c |    2 ++
 1 file changed, 2 insertions(+)

Index: 2.6-git/kernel/cpu.c
===================================================================
--- 2.6-git.orig/kernel/cpu.c
+++ 2.6-git/kernel/cpu.c
@@ -150,6 +150,7 @@ static int _cpu_down(unsigned int cpu, i
 	err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
 					hcpu, -1, &nr_calls);
 	if (err == NOTIFY_BAD) {
+		nr_calls--;
 		__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
 					  hcpu, nr_calls, NULL);
 		printk("%s: attempt to take down CPU %u failed\n",
@@ -233,6 +234,7 @@ static int __cpuinit _cpu_up(unsigned in
 	ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu,
 							-1, &nr_calls);
 	if (ret == NOTIFY_BAD) {
+		nr_calls--;
 		printk("%s: attempt to bring up CPU %u failed\n",
 				__FUNCTION__, cpu);
 		ret = -EINVAL;

-- 

[patch 4/9] topology: remove topology_dev_map

[Akinobu Mita]

[-- Attachment #1: topology-cpuhotplug-cleanup.patch --]
[-- Type: text/plain, Size: 1292 bytes --]

By previous cpu hotplug notifier change, we don't need to track
topology_dev existence for each cpu by topology_dev_map.

Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 drivers/base/topology.c |   11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

Index: 2.6-git/drivers/base/topology.c
===================================================================
--- 2.6-git.orig/drivers/base/topology.c
+++ 2.6-git/drivers/base/topology.c
@@ -94,27 +94,18 @@ static struct attribute_group topology_a
 	.name = "topology"
 };
 
-static cpumask_t topology_dev_map = CPU_MASK_NONE;
-
 /* Add/Remove cpu_topology interface for CPU device */
 static int __cpuinit topology_add_dev(unsigned int cpu)
 {
-	int rc;
 	struct sys_device *sys_dev = get_cpu_sysdev(cpu);
 
-	rc = sysfs_create_group(&sys_dev->kobj, &topology_attr_group);
-	if (!rc)
-		cpu_set(cpu, topology_dev_map);
-	return rc;
+	return sysfs_create_group(&sys_dev->kobj, &topology_attr_group);
 }
 
 static void __cpuinit topology_remove_dev(unsigned int cpu)
 {
 	struct sys_device *sys_dev = get_cpu_sysdev(cpu);
 
-	if (!cpu_isset(cpu, topology_dev_map))
-		return;
-	cpu_clear(cpu, topology_dev_map);
 	sysfs_remove_group(&sys_dev->kobj, &topology_attr_group);
 }
 

-- 

[patch 5/9] thermal_throttle: fix cpu hotplug error handling

[Akinobu Mita]

[-- Attachment #1: therm_throt-hotplug.patch --]
[-- Type: text/plain, Size: 1341 bytes --]

Do thermal_throttle_add_dev() in CPU_UP_PREPARE instead of CPU_ONLINE.

Cc: Dmitriy Zavin <dmitriyz@google.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 arch/i386/kernel/cpu/mcheck/therm_throt.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Index: 2.6-git/arch/i386/kernel/cpu/mcheck/therm_throt.c
===================================================================
--- 2.6-git.orig/arch/i386/kernel/cpu/mcheck/therm_throt.c
+++ 2.6-git/arch/i386/kernel/cpu/mcheck/therm_throt.c
@@ -131,17 +131,19 @@ static __cpuinit int thermal_throttle_cp
 {
 	unsigned int cpu = (unsigned long)hcpu;
 	struct sys_device *sys_dev;
-	int err;
+	int err = 0;
 
 	sys_dev = get_cpu_sysdev(cpu);
 	switch (action) {
-	case CPU_ONLINE:
-	case CPU_ONLINE_FROZEN:
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
 		mutex_lock(&therm_cpu_lock);
 		err = thermal_throttle_add_dev(sys_dev);
 		mutex_unlock(&therm_cpu_lock);
 		WARN_ON(err);
 		break;
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
 		mutex_lock(&therm_cpu_lock);
@@ -149,7 +151,7 @@ static __cpuinit int thermal_throttle_cp
 		mutex_unlock(&therm_cpu_lock);
 		break;
 	}
-	return NOTIFY_OK;
+	return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
 static struct notifier_block thermal_throttle_cpu_notifier =

-- 

[patch 6/9] msr: fix cpu hotplug error handling

[Akinobu Mita]

[-- Attachment #1: msr-cpuhotplug.patch --]
[-- Type: text/plain, Size: 2271 bytes --]

Do msr_device_create() in CPU_UP_PREPARE instead of CPU_ONLINE.

Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 arch/i386/kernel/msr.c |   32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

Index: 2.6-git/arch/i386/kernel/msr.c
===================================================================
--- 2.6-git.orig/arch/i386/kernel/msr.c
+++ 2.6-git/arch/i386/kernel/msr.c
@@ -135,33 +135,39 @@ static const struct file_operations msr_
 	.open = msr_open,
 };
 
-static int msr_device_create(int i)
+static int msr_device_create(int cpu)
 {
-	int err = 0;
 	struct device *dev;
 
-	dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, i), "msr%d",i);
-	if (IS_ERR(dev))
-		err = PTR_ERR(dev);
-	return err;
+	dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu),
+			    "msr%d", cpu);
+	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
+}
+
+static void msr_device_destroy(int cpu)
+{
+	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
 }
 
 static int msr_class_cpu_callback(struct notifier_block *nfb,
 				unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
+	int err = 0;
 
 	switch (action) {
-	case CPU_ONLINE:
-	case CPU_ONLINE_FROZEN:
-		msr_device_create(cpu);
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		err = msr_device_create(cpu);
 		break;
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
-		device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
+		msr_device_destroy(cpu);
 		break;
 	}
-	return NOTIFY_OK;
+	return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
 static struct notifier_block __cpuinitdata msr_class_cpu_notifier =
@@ -198,7 +204,7 @@ static int __init msr_init(void)
 out_class:
 	i = 0;
 	for_each_online_cpu(i)
-		device_destroy(msr_class, MKDEV(MSR_MAJOR, i));
+		msr_device_destroy(i);
 	class_destroy(msr_class);
 out_chrdev:
 	unregister_chrdev(MSR_MAJOR, "cpu/msr");
@@ -210,7 +216,7 @@ static void __exit msr_exit(void)
 {
 	int cpu = 0;
 	for_each_online_cpu(cpu)
-		device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
+		msr_device_destroy(cpu);
 	class_destroy(msr_class);
 	unregister_chrdev(MSR_MAJOR, "cpu/msr");
 	unregister_hotcpu_notifier(&msr_class_cpu_notifier);

-- 

[patch 7/9] cpuid: fix cpu hotplug error handling

[Akinobu Mita]

[-- Attachment #1: cpuid-cpuhotplug.patch --]
[-- Type: text/plain, Size: 2298 bytes --]

Do cpuid_device_create() in CPU_UP_PREPARE instead of CPU_ONLINE.

Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 arch/i386/kernel/cpuid.c |   32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

Index: 2.6-git/arch/i386/kernel/cpuid.c
===================================================================
--- 2.6-git.orig/arch/i386/kernel/cpuid.c
+++ 2.6-git/arch/i386/kernel/cpuid.c
@@ -152,32 +152,38 @@ static const struct file_operations cpui
 	.open = cpuid_open,
 };
 
-static int cpuid_device_create(int i)
+static int cpuid_device_create(int cpu)
 {
-	int err = 0;
 	struct device *dev;
 
-	dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, i), "cpu%d",i);
-	if (IS_ERR(dev))
-		err = PTR_ERR(dev);
-	return err;
+	dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu),
+			    "cpu%d", cpu);
+	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
+}
+
+static void cpuid_device_destroy(int cpu)
+{
+	device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
 }
 
 static int cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
+	int err = 0;
 
 	switch (action) {
-	case CPU_ONLINE:
-	case CPU_ONLINE_FROZEN:
-		cpuid_device_create(cpu);
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		err = cpuid_device_create(cpu);
 		break;
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
-		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
+		cpuid_device_destroy(cpu);
 		break;
 	}
-	return NOTIFY_OK;
+	return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
 static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier =
@@ -214,7 +220,7 @@ static int __init cpuid_init(void)
 out_class:
 	i = 0;
 	for_each_online_cpu(i) {
-		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, i));
+		cpuid_device_destroy(i);
 	}
 	class_destroy(cpuid_class);
 out_chrdev:
@@ -228,7 +234,7 @@ static void __exit cpuid_exit(void)
 	int cpu = 0;
 
 	for_each_online_cpu(cpu)
-		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
+		cpuid_device_destroy(cpu);
 	class_destroy(cpuid_class);
 	unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 	unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);

-- 

[patch 8/9] mce: fix cpu hotplug error handling

[Akinobu Mita]

[-- Attachment #1: mce-cpuhotplug.patch --]
[-- Type: text/plain, Size: 3023 bytes --]


- Clear kobject in percpu device_mce before calling sysdev_register() with

  Because mce_create_device() may fail and it leaves kobject filled with
  junk. It will be the problem when mce_create_device() will be called
  next time.

- Fix error handling in mce_create_device()

  Error handling should not do sysdev_remove_file() with not yet added
  attributes.

- Don't register hotcpu notifier when mce_create_device() returns error

- Do mce_create_device() in CPU_UP_PREPARE instead of CPU_ONLINE

Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 arch/x86_64/kernel/mce.c |   39 +++++++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 10 deletions(-)

Index: 2.6-git/arch/x86_64/kernel/mce.c
===================================================================
--- 2.6-git.orig/arch/x86_64/kernel/mce.c
+++ 2.6-git/arch/x86_64/kernel/mce.c
@@ -690,16 +690,29 @@ static __cpuinit int mce_create_device(u
 	if (!mce_available(&cpu_data[cpu]))
 		return -EIO;
 
+	memset(&per_cpu(device_mce, cpu).kobj, 0, sizeof(struct kobject));
 	per_cpu(device_mce,cpu).id = cpu;
 	per_cpu(device_mce,cpu).cls = &mce_sysclass;
 
 	err = sysdev_register(&per_cpu(device_mce,cpu));
+	if (err)
+		return err;
+
+	for (i = 0; mce_attributes[i]; i++) {
+		err = sysdev_create_file(&per_cpu(device_mce,cpu),
+					 mce_attributes[i]);
+		if (err)
+			goto error;
+	}
 
-	if (!err) {
-		for (i = 0; mce_attributes[i]; i++)
-			sysdev_create_file(&per_cpu(device_mce,cpu),
-				mce_attributes[i]);
+	return 0;
+error:
+	while (i--) {
+		sysdev_remove_file(&per_cpu(device_mce,cpu),
+				   mce_attributes[i]);
 	}
+	sysdev_unregister(&per_cpu(device_mce,cpu));
+
 	return err;
 }
 
@@ -711,7 +724,6 @@ static void mce_remove_device(unsigned i
 		sysdev_remove_file(&per_cpu(device_mce,cpu),
 			mce_attributes[i]);
 	sysdev_unregister(&per_cpu(device_mce,cpu));
-	memset(&per_cpu(device_mce, cpu).kobj, 0, sizeof(struct kobject));
 }
 
 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
@@ -719,18 +731,21 @@ static int
 mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
+	int err = 0;
 
 	switch (action) {
-	case CPU_ONLINE:
-	case CPU_ONLINE_FROZEN:
-		mce_create_device(cpu);
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		err = mce_create_device(cpu);
 		break;
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
 		mce_remove_device(cpu);
 		break;
 	}
-	return NOTIFY_OK;
+	return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
 static struct notifier_block mce_cpu_notifier = {
@@ -745,9 +760,13 @@ static __init int mce_init_device(void)
 	if (!mce_available(&boot_cpu_data))
 		return -EIO;
 	err = sysdev_class_register(&mce_sysclass);
+	if (err)
+		return err;
 
 	for_each_online_cpu(i) {
-		mce_create_device(i);
+		err = mce_create_device(i);
+		if (err)
+			return err;
 	}
 
 	register_hotcpu_notifier(&mce_cpu_notifier);

-- 

[patch 9/9] intel_cacheinfo: fix cpu hotplug error handling

[Akinobu Mita]

[-- Attachment #1: intel-cacheinfo-cpu-hotplug.patch --]
[-- Type: text/plain, Size: 5042 bytes --]

- Fix resource leakage in error case within detect_cache_attributes()

- Don't register hotcpu notifier when cache_add_dev() returns error

- Introduce cache_dev_map cpumask to track whether cache interface for
  CPU is successfully added by cache_add_dev() or not.

  cache_add_dev() may fail with out of memory error. In order to
  avoid cache_remove_dev() with that uninitialized cache interface when
  CPU_DEAD event is delivered we need to have the cache_dev_map cpumask.

  (We cannot change cache_add_dev() from CPU_ONLINE event handler
  to CPU_UP_PREPARE event handler. Because cache_add_dev() needs
  to do cpuid and store the results with its CPU online.)

Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 arch/i386/kernel/cpu/intel_cacheinfo.c |   64 +++++++++++++++++++++++----------
 1 file changed, 45 insertions(+), 19 deletions(-)

Index: 2.6-git/arch/i386/kernel/cpu/intel_cacheinfo.c
===================================================================
--- 2.6-git.orig/arch/i386/kernel/cpu/intel_cacheinfo.c
+++ 2.6-git/arch/i386/kernel/cpu/intel_cacheinfo.c
@@ -466,6 +466,11 @@ static void __init cache_remove_shared_c
 
 static void free_cache_attributes(unsigned int cpu)
 {
+	int i;
+
+	for (i = 0; i < num_cache_leaves; i++)
+		cache_remove_shared_cpu_map(cpu, i);
+
 	kfree(cpuid4_info[cpu]);
 	cpuid4_info[cpu] = NULL;
 }
@@ -473,8 +478,8 @@ static void free_cache_attributes(unsign
 static int __cpuinit detect_cache_attributes(unsigned int cpu)
 {
 	struct _cpuid4_info	*this_leaf;
-	unsigned long 		j;
-	int 			retval;
+	unsigned long		j;
+	int			retval;
 	cpumask_t		oldmask;
 
 	if (num_cache_leaves == 0)
@@ -491,19 +496,26 @@ static int __cpuinit detect_cache_attrib
 		goto out;
 
 	/* Do cpuid and store the results */
-	retval = 0;
 	for (j = 0; j < num_cache_leaves; j++) {
 		this_leaf = CPUID4_INFO_IDX(cpu, j);
 		retval = cpuid4_cache_lookup(j, this_leaf);
-		if (unlikely(retval < 0))
+		if (unlikely(retval < 0)) {
+			int i;
+
+			for (i = 0; i < j; i++)
+				cache_remove_shared_cpu_map(cpu, i);
 			break;
+		}
 		cache_shared_cpu_map_setup(cpu, j);
 	}
 	set_cpus_allowed(current, oldmask);
 
 out:
-	if (retval)
-		free_cache_attributes(cpu);
+	if (retval) {
+		kfree(cpuid4_info[cpu]);
+		cpuid4_info[cpu] = NULL;
+	}
+
 	return retval;
 }
 
@@ -647,13 +659,14 @@ static void cpuid4_cache_sysfs_exit(unsi
 
 static int __cpuinit cpuid4_cache_sysfs_init(unsigned int cpu)
 {
+	int err;
 
 	if (num_cache_leaves == 0)
 		return -ENOENT;
 
-	detect_cache_attributes(cpu);
-	if (cpuid4_info[cpu] == NULL)
-		return -ENOENT;
+	err = detect_cache_attributes(cpu);
+	if (err)
+		return err;
 
 	/* Allocate all required memory */
 	cache_kobject[cpu] = kzalloc(sizeof(struct kobject), GFP_KERNEL);
@@ -672,13 +685,15 @@ err_out:
 	return -ENOMEM;
 }
 
+static cpumask_t cache_dev_map = CPU_MASK_NONE;
+
 /* Add/Remove cache interface for CPU device */
 static int __cpuinit cache_add_dev(struct sys_device * sys_dev)
 {
 	unsigned int cpu = sys_dev->id;
 	unsigned long i, j;
 	struct _index_kobject *this_object;
-	int retval = 0;
+	int retval;
 
 	retval = cpuid4_cache_sysfs_init(cpu);
 	if (unlikely(retval < 0))
@@ -688,6 +703,10 @@ static int __cpuinit cache_add_dev(struc
 	kobject_set_name(cache_kobject[cpu], "%s", "cache");
 	cache_kobject[cpu]->ktype = &ktype_percpu_entry;
 	retval = kobject_register(cache_kobject[cpu]);
+	if (retval < 0) {
+		cpuid4_cache_sysfs_exit(cpu);
+		return retval;
+	}
 
 	for (i = 0; i < num_cache_leaves; i++) {
 		this_object = INDEX_KOBJECT_PTR(cpu,i);
@@ -707,6 +726,9 @@ static int __cpuinit cache_add_dev(struc
 			break;
 		}
 	}
+	if (!retval)
+		cpu_set(cpu, cache_dev_map);
+
 	return retval;
 }
 
@@ -715,13 +737,14 @@ static void __cpuexit cache_remove_dev(s
 	unsigned int cpu = sys_dev->id;
 	unsigned long i;
 
-	for (i = 0; i < num_cache_leaves; i++) {
-		cache_remove_shared_cpu_map(cpu, i);
+	if (!cpu_isset(cpu, cache_dev_map))
+		return;
+	cpu_clear(cpu, cache_dev_map);
+
+	for (i = 0; i < num_cache_leaves; i++)
 		kobject_unregister(&(INDEX_KOBJECT_PTR(cpu,i)->kobj));
-	}
 	kobject_unregister(cache_kobject[cpu]);
 	cpuid4_cache_sysfs_exit(cpu);
-	return;
 }
 
 static int __cpuinit cacheinfo_cpu_callback(struct notifier_block *nfb,
@@ -746,7 +769,7 @@ static int __cpuinit cacheinfo_cpu_callb
 
 static struct notifier_block __cpuinitdata cacheinfo_cpu_notifier =
 {
-    .notifier_call = cacheinfo_cpu_callback,
+	.notifier_call = cacheinfo_cpu_callback,
 };
 
 static int __cpuinit cache_sysfs_init(void)
@@ -756,12 +779,15 @@ static int __cpuinit cache_sysfs_init(vo
 	if (num_cache_leaves == 0)
 		return 0;
 
-	register_hotcpu_notifier(&cacheinfo_cpu_notifier);
-
 	for_each_online_cpu(i) {
-		cacheinfo_cpu_callback(&cacheinfo_cpu_notifier, CPU_ONLINE,
-			(void *)(long)i);
+		int err;
+		struct sys_device *sys_dev = get_cpu_sysdev(i);
+
+		err = cache_add_dev(sys_dev);
+		if (err)
+			return err;
 	}
+	register_hotcpu_notifier(&cacheinfo_cpu_notifier);
 
 	return 0;
 }

-- 

Re: [patch 3/9] cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE

[Rusty Russell]

On Mon, 2007-07-23 at 00:33 +0900, Akinobu Mita wrote:
> plain text document attachment (cpuhotplug-nr-calls.patch)
> From: Akinobu Mita <akinobu.mita@gmail.com>
> 
> The functions in a CPU notifier chain is called with CPU_UP_PREPARE event
> before making the CPU online. If one of the callback returns NOTIFY_BAD,
> it stops to deliver CPU_UP_PREPARE event, and CPU online operation is canceled.
> Then CPU_UP_CANCELED event is delivered to the functions in a CPU notifier
> chain again.
> 
> This CPU_UP_CANCELED event is delivered to the functions which have been
> called with CPU_UP_PREPARE, not delivered to the functions which haven't
> been called with CPU_UP_PREPARE.
> 
> The problem that makes existing cpu hotplug error handlings complex is
> that the CPU_UP_CANCELED event is delivered to the function that has
> returned NOTIFY_BAD, too.
> 
> Usually we don't expect to call destructor function against the
> object that has failed to initialize. It is like:
> 
> 	err = register_something();
> 	if (err) {
> 		unregister_something();
> 		return err;
> 	}
> 
> So it is natural to deliver CPU_UP_CANCELED event only to the functions
> that have returned NOTIFY_OK with CPU_UP_PREPARE event and not to call
> the function that have returned NOTIFY_BAD. This is what this patch is doing.
> 
> Otherwise, every cpu hotplug notifiler has to track whether
> notifiler event is failed or not for each cpu.
> (drivers/base/topology.c is doing this with topology_dev_map)
> 
> Similary this patch makes same thing with CPU_DOWN_PREPARE and
> CPU_DOWN_FAILED evnets.
> 
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

This makes a great deal of sense; I consider it a bugfix.

Thanks!
Rusty.

Re: [patch 4/9] topology: remove topology_dev_map

[Greg KH]

On Mon, Jul 23, 2007 at 12:33:16AM +0900, Akinobu Mita wrote:
> By previous cpu hotplug notifier change, we don't need to track
> topology_dev existence for each cpu by topology_dev_map.
> 
> Cc: Greg Kroah-Hartman <gregkh@suse.de>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

I'm guessing that this is going to have to go in through some other tree
than mine, so feel free to add:

Acked-by: Greg Kroah-Hartman <gregkh@suse.de>

to it.

thanks,

greg k-h

Re: [patch 2/9] slab: fix memory leak in cpu hotplug error path

[Pekka Enberg]

On 7/22/07, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> This patch fixes memory leak in error path.
>
> In reality, we don't need to call cpuup_canceled(cpu) for now.
> But upcoming cpu hotplug error handling change needs this.

This and the previous patch look good to me.

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>