[PATCH 01/12] cpu-hotplug: introduce cpu_notify(), __cpu_notify(), cpu_notify_nofail()

[PATCH 01/12] cpu-hotplug: introduce cpu_notify(), __cpu_notify(), cpu_notify_nofail()

[Akinobu Mita]

No functional change.
These are just wrappers of raw_cpu_notifier_call_chain.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
---
 kernel/cpu.c |   55 ++++++++++++++++++++++++++++++++-----------------------
 1 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index f8cced2..bc9c301 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -133,6 +133,26 @@ int __ref register_cpu_notifier(struct notifier_block *nb)
 	return ret;
 }
 
+static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
+			int *nr_calls)
+{
+	return __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
+					nr_calls);
+}
+
+static int cpu_notify(unsigned long val, void *v)
+{
+	return __cpu_notify(val, v, -1, NULL);
+}
+
+static void cpu_notify_nofail(unsigned long val, void *v)
+{
+	int err;
+
+	err = cpu_notify(val, v);
+	BUG_ON(err == NOTIFY_BAD);
+}
+
 #ifdef CONFIG_HOTPLUG_CPU
 
 EXPORT_SYMBOL(register_cpu_notifier);
@@ -178,8 +198,7 @@ static int __ref take_cpu_down(void *_param)
 	if (err < 0)
 		return err;
 
-	raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
-				param->hcpu);
+	cpu_notify(CPU_DYING | param->mod, param->hcpu);
 
 	/* Force idle task to run as soon as we yield: it should
 	   immediately notice cpu is offline and die quickly. */
@@ -210,14 +229,12 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 
 	cpu_hotplug_begin();
 	set_cpu_active(cpu, false);
-	err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
-					hcpu, -1, &nr_calls);
+	err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
 	if (err == NOTIFY_BAD) {
 		set_cpu_active(cpu, true);
 
 		nr_calls--;
-		__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
-					  hcpu, nr_calls, NULL);
+		__cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
 		printk("%s: attempt to take down CPU %u failed\n",
 				__func__, cpu);
 		err = -EINVAL;
@@ -232,9 +249,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 	if (err) {
 		set_cpu_active(cpu, true);
 		/* CPU didn't die: tell everyone.  Can't complain. */
-		if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
-					    hcpu) == NOTIFY_BAD)
-			BUG();
+		cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
 
 		goto out_allowed;
 	}
@@ -248,9 +263,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 	__cpu_die(cpu);
 
 	/* CPU is completely dead: tell everyone.  Too late to complain. */
-	if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod,
-				    hcpu) == NOTIFY_BAD)
-		BUG();
+	cpu_notify_nofail(CPU_DEAD | mod, hcpu);
 
 	check_for_tasks(cpu);
 
@@ -258,11 +271,9 @@ out_allowed:
 	set_cpus_allowed_ptr(current, old_allowed);
 out_release:
 	cpu_hotplug_done();
-	if (!err) {
-		if (raw_notifier_call_chain(&cpu_chain, CPU_POST_DEAD | mod,
-					    hcpu) == NOTIFY_BAD)
-			BUG();
-	}
+	if (!err)
+		cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
+
 	free_cpumask_var(old_allowed);
 	return err;
 }
@@ -302,8 +313,7 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
 		return -EINVAL;
 
 	cpu_hotplug_begin();
-	ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu,
-							-1, &nr_calls);
+	ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
 	if (ret == NOTIFY_BAD) {
 		nr_calls--;
 		printk("%s: attempt to bring up CPU %u failed\n",
@@ -321,12 +331,11 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
 	set_cpu_active(cpu, true);
 
 	/* Now call notifier in preparation. */
-	raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu);
+	cpu_notify(CPU_ONLINE | mod, hcpu);
 
 out_notify:
 	if (ret != 0)
-		__raw_notifier_call_chain(&cpu_chain,
-				CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
+		__cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 	cpu_hotplug_done();
 
 	return ret;
@@ -466,7 +475,7 @@ void __cpuinit notify_cpu_starting(unsigned int cpu)
 	if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
 		val = CPU_STARTING_FROZEN;
 #endif /* CONFIG_PM_SLEEP_SMP */
-	raw_notifier_call_chain(&cpu_chain, val, (void *)(long)cpu);
+	cpu_notify(val, (void *)(long)cpu);
 }
 
 #endif /* CONFIG_SMP */
-- 
1.6.0.6

[PATCH 02/12] cpu-hotplug: return better errno on cpu hotplug failure

[Akinobu Mita]

Currently, onlining or offlining a CPU failure by one of the cpu
notifiers error always cause -EINVAL error.
(i.e. writing 0 or 1 to /sys/devices/system/cpu/cpuX/online gets EINVAL)

To get better error reporting rather than always getting -EINVAL,
This changes cpu_notify() to return -errno value with notifier_to_errno() and
fix the callers. Now that cpu notifiers can return encapsulate errno value.

Currently, all cpu hotplug notifiers return NOTIFY_OK, NOTIFY_BAD,
or NOTIFY_DONE. So cpu_notify() can returns 0 or -EPERM with this change
for now.
(notifier_to_errno(NOTIFY_OK) == 0, notifier_to_errno(NOTIFY_DONE) == 0,
notifier_to_errno(NOTIFY_BAD) == -EPERM)

Forthcoming patches convert several cpu notifiers to return encapsulate
errno value with notifier_from_errno().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
---
 kernel/cpu.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index bc9c301..d3f335e 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -136,8 +136,12 @@ int __ref register_cpu_notifier(struct notifier_block *nb)
 static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
 			int *nr_calls)
 {
-	return __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
+	int ret;
+
+	ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
 					nr_calls);
+
+	return notifier_to_errno(ret);
 }
 
 static int cpu_notify(unsigned long val, void *v)
@@ -150,7 +154,7 @@ static void cpu_notify_nofail(unsigned long val, void *v)
 	int err;
 
 	err = cpu_notify(val, v);
-	BUG_ON(err == NOTIFY_BAD);
+	BUG_ON(err);
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -230,14 +234,13 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 	cpu_hotplug_begin();
 	set_cpu_active(cpu, false);
 	err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
-	if (err == NOTIFY_BAD) {
+	if (err) {
 		set_cpu_active(cpu, true);
 
 		nr_calls--;
 		__cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
 		printk("%s: attempt to take down CPU %u failed\n",
 				__func__, cpu);
-		err = -EINVAL;
 		goto out_release;
 	}
 
@@ -314,11 +317,10 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
 
 	cpu_hotplug_begin();
 	ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
-	if (ret == NOTIFY_BAD) {
+	if (ret) {
 		nr_calls--;
 		printk("%s: attempt to bring up CPU %u failed\n",
 				__func__, cpu);
-		ret = -EINVAL;
 		goto out_notify;
 	}
 
-- 
1.6.0.6

[PATCH 03/12] notifier: change notifier_from_errno(0) to return NOTIFY_OK

[Akinobu Mita]

This changes notifier_from_errno(0) to be NOTIFY_OK instead of
NOTIFY_STOP_MASK | NOTIFY_OK.

Currently, the notifiers which return encapsulated errno value have to
do something like this:

	err = do_something(); // returns -errno
	if (err)
		return notifier_from_errno(err);
	else
		return NOTIFY_OK;

This change makes the above code simple:

	err = do_something(); // returns -errno

	return return notifier_from_errno(err);

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 include/linux/notifier.h |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index fee6c2f..9e4831d 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -164,7 +164,10 @@ extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
 /* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */
 static inline int notifier_from_errno(int err)
 {
-	return NOTIFY_STOP_MASK | (NOTIFY_OK - err);
+	if (err)
+		return NOTIFY_STOP_MASK | (NOTIFY_OK - err);
+
+	return NOTIFY_OK;
 }
 
 /* Restore (negative) errno value from notify return value. */
-- 
1.6.0.6

[PATCH 04/12] x86: convert cpu notifier to return encapsulate errno value

[Akinobu Mita]

By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for msr, cpuid, and
therm_throt.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
---
 arch/x86/kernel/cpu/mcheck/therm_throt.c |    2 +-
 arch/x86/kernel/cpuid.c                  |    2 +-
 arch/x86/kernel/msr.c                    |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
index 81c499e..e1a0a3b 100644
--- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
@@ -190,7 +190,7 @@ thermal_throttle_cpu_callback(struct notifier_block *nfb,
 		mutex_unlock(&therm_cpu_lock);
 		break;
 	}
-	return err ? NOTIFY_BAD : NOTIFY_OK;
+	return notifier_from_errno(err);
 }
 
 static struct notifier_block thermal_throttle_cpu_notifier __cpuinitdata =
diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index 83e5e62..caf11b5 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -169,7 +169,7 @@ static int __cpuinit cpuid_class_cpu_callback(struct notifier_block *nfb,
 		cpuid_device_destroy(cpu);
 		break;
 	}
-	return err ? NOTIFY_BAD : NOTIFY_OK;
+	return notifier_from_errno(err);
 }
 
 static struct notifier_block __refdata cpuid_class_cpu_notifier =
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 206735a..823081b 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -229,7 +229,7 @@ static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb,
 		msr_device_destroy(cpu);
 		break;
 	}
-	return err ? NOTIFY_BAD : NOTIFY_OK;
+	return notifier_from_errno(err);
 }
 
 static struct notifier_block __refdata msr_class_cpu_notifier = {
-- 
1.6.0.6

[PATCH 05/12] topology: convert cpu notifier to return encapsulate errno value

[Akinobu Mita]

By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for topology.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
---
 drivers/base/topology.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/base/topology.c b/drivers/base/topology.c
index bf6b132..9fc630c 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -162,7 +162,7 @@ static int __cpuinit topology_cpu_callback(struct notifier_block *nfb,
 		topology_remove_dev(cpu);
 		break;
 	}
-	return rc ? NOTIFY_BAD : NOTIFY_OK;
+	return notifier_from_errno(rc);
 }
 
 static int __cpuinit topology_sysfs_init(void)
-- 
1.6.0.6

[PATCH 06/12] kernel/: convert cpu notifier to return encapsulate errno value

[Akinobu Mita]

By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for kernel/*.c

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 kernel/padata.c     |    4 ++--
 kernel/profile.c    |    4 ++--
 kernel/relay.c      |    2 +-
 kernel/sched.c      |    2 +-
 kernel/smp.c        |    2 +-
 kernel/softirq.c    |    2 +-
 kernel/softlockup.c |    2 +-
 kernel/timer.c      |    7 +++++--
 kernel/workqueue.c  |    9 +++++----
 9 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/kernel/padata.c b/kernel/padata.c
index 93caf65..c610d12 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -587,7 +587,7 @@ static int __cpuinit padata_cpu_callback(struct notifier_block *nfb,
 		err = __padata_add_cpu(pinst, cpu);
 		mutex_unlock(&pinst->lock);
 		if (err)
-			return NOTIFY_BAD;
+			return notifier_from_errno(err);
 		break;
 
 	case CPU_DOWN_PREPARE:
@@ -598,7 +598,7 @@ static int __cpuinit padata_cpu_callback(struct notifier_block *nfb,
 		err = __padata_remove_cpu(pinst, cpu);
 		mutex_unlock(&pinst->lock);
 		if (err)
-			return NOTIFY_BAD;
+			return notifier_from_errno(err);
 		break;
 
 	case CPU_UP_CANCELED:
diff --git a/kernel/profile.c b/kernel/profile.c
index a55d3a3..cbf2677 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -370,7 +370,7 @@ static int __cpuinit profile_cpu_callback(struct notifier_block *info,
 					GFP_KERNEL | __GFP_ZERO,
 					0);
 			if (!page)
-				return NOTIFY_BAD;
+				return notifier_from_errno(-ENOMEM);
 			per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
 		}
 		if (!per_cpu(cpu_profile_hits, cpu)[0]) {
@@ -386,7 +386,7 @@ out_free:
 		page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
 		per_cpu(cpu_profile_hits, cpu)[1] = NULL;
 		__free_page(page);
-		return NOTIFY_BAD;
+		return notifier_from_errno(-ENOMEM);
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
 		if (prof_cpu_mask != NULL)
diff --git a/kernel/relay.c b/kernel/relay.c
index 3d97f28..29714bf 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -539,7 +539,7 @@ static int __cpuinit relay_hotcpu_callback(struct notifier_block *nb,
 					"relay_hotcpu_callback: cpu %d buffer "
 					"creation failed\n", hotcpu);
 				mutex_unlock(&relay_channels_mutex);
-				return NOTIFY_BAD;
+				return notifier_from_errno(-ENOMEM);
 			}
 		}
 		mutex_unlock(&relay_channels_mutex);
diff --git a/kernel/sched.c b/kernel/sched.c
index c61e58a..873b9d1 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5887,7 +5887,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
 	case CPU_UP_PREPARE_FROZEN:
 		p = kthread_create(migration_thread, hcpu, "migration/%d", cpu);
 		if (IS_ERR(p))
-			return NOTIFY_BAD;
+			return notifier_from_errno(PTR_ERR(p));
 		kthread_bind(p, cpu);
 		/* Must be high prio: stop_machine expects to yield to it. */
 		rq = task_rq_lock(p, &flags);
diff --git a/kernel/smp.c b/kernel/smp.c
index 9867b6b..cb2a6c6 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -51,7 +51,7 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
 	case CPU_UP_PREPARE_FROZEN:
 		if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
 				cpu_to_node(cpu)))
-			return NOTIFY_BAD;
+			return notifier_from_errno(-ENOMEM);
 		break;
 
 #ifdef CONFIG_HOTPLUG_CPU
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 7c1a67e..2ca2323 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -808,7 +808,7 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb,
 		p = kthread_create(run_ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu);
 		if (IS_ERR(p)) {
 			printk("ksoftirqd for %i failed\n", hotcpu);
-			return NOTIFY_BAD;
+			return notifier_from_errno(PTR_ERR(p));
 		}
 		kthread_bind(p, hotcpu);
   		per_cpu(ksoftirqd, hotcpu) = p;
diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 0d4c789..46af4c5 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -228,7 +228,7 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 		p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
 		if (IS_ERR(p)) {
 			printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
-			return NOTIFY_BAD;
+			return notifier_from_errno(PTR_ERR(p));
 		}
 		per_cpu(softlockup_touch_ts, hotcpu) = 0;
 		per_cpu(softlockup_watchdog, hotcpu) = p;
diff --git a/kernel/timer.c b/kernel/timer.c
index c61a794..bc7e930 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1618,11 +1618,14 @@ static int __cpuinit timer_cpu_notify(struct notifier_block *self,
 				unsigned long action, void *hcpu)
 {
 	long cpu = (long)hcpu;
+	int err;
+
 	switch(action) {
 	case CPU_UP_PREPARE:
 	case CPU_UP_PREPARE_FROZEN:
-		if (init_timers_cpu(cpu) < 0)
-			return NOTIFY_BAD;
+		err = init_timers_cpu(cpu);
+		if (err < 0)
+			return notifier_from_errno(err);
 		break;
 #ifdef CONFIG_HOTPLUG_CPU
 	case CPU_DEAD:
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index dee4865..5aa45a0 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1076,7 +1076,7 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
 	unsigned int cpu = (unsigned long)hcpu;
 	struct cpu_workqueue_struct *cwq;
 	struct workqueue_struct *wq;
-	int ret = NOTIFY_OK;
+	int err = 0;
 
 	action &= ~CPU_TASKS_FROZEN;
 
@@ -1090,12 +1090,13 @@ undo:
 
 		switch (action) {
 		case CPU_UP_PREPARE:
-			if (!create_workqueue_thread(cwq, cpu))
+			err = create_workqueue_thread(cwq, cpu);
+			if (!err)
 				break;
 			printk(KERN_ERR "workqueue [%s] for %i failed\n",
 				wq->name, cpu);
 			action = CPU_UP_CANCELED;
-			ret = NOTIFY_BAD;
+			err = -ENOMEM;
 			goto undo;
 
 		case CPU_ONLINE:
@@ -1116,7 +1117,7 @@ undo:
 		cpumask_clear_cpu(cpu, cpu_populated_map);
 	}
 
-	return ret;
+	return notifier_from_errno(err);
 }
 
 #ifdef CONFIG_SMP
-- 
1.6.0.6

[PATCH 07/12] slab: convert cpu notifier to return encapsulate errno value

[Akinobu Mita]

By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for slab.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Matt Mackall <mpm@selenic.com>
Cc: linux-mm@kvack.org
---
 mm/slab.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index a9f325b..d57309e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1324,7 +1324,7 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
 		mutex_unlock(&cache_chain_mutex);
 		break;
 	}
-	return err ? NOTIFY_BAD : NOTIFY_OK;
+	return notifier_from_errno(err);
 }
 
 static struct notifier_block __cpuinitdata cpucache_notifier = {
-- 
1.6.0.6

[PATCH 08/12] iucv: convert cpu notifier to return encapsulate errno value

[Akinobu Mita]

By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for iucv.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Ursula Braun <ursula.braun@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: linux-s390@vger.kernel.org
---
 net/iucv/iucv.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
index fd8b283..f28ad2c 100644
--- a/net/iucv/iucv.c
+++ b/net/iucv/iucv.c
@@ -632,13 +632,14 @@ static int __cpuinit iucv_cpu_notify(struct notifier_block *self,
 		iucv_irq_data[cpu] = kmalloc_node(sizeof(struct iucv_irq_data),
 					GFP_KERNEL|GFP_DMA, cpu_to_node(cpu));
 		if (!iucv_irq_data[cpu])
-			return NOTIFY_BAD;
+			return notifier_from_errno(-ENOMEM);
+
 		iucv_param[cpu] = kmalloc_node(sizeof(union iucv_param),
 				     GFP_KERNEL|GFP_DMA, cpu_to_node(cpu));
 		if (!iucv_param[cpu]) {
 			kfree(iucv_irq_data[cpu]);
 			iucv_irq_data[cpu] = NULL;
-			return NOTIFY_BAD;
+			return notifier_from_errno(-ENOMEM);
 		}
 		iucv_param_irq[cpu] = kmalloc_node(sizeof(union iucv_param),
 					GFP_KERNEL|GFP_DMA, cpu_to_node(cpu));
@@ -647,7 +648,7 @@ static int __cpuinit iucv_cpu_notify(struct notifier_block *self,
 			iucv_param[cpu] = NULL;
 			kfree(iucv_irq_data[cpu]);
 			iucv_irq_data[cpu] = NULL;
-			return NOTIFY_BAD;
+			return notifier_from_errno(-ENOMEM);
 		}
 		break;
 	case CPU_UP_CANCELED:
@@ -677,7 +678,7 @@ static int __cpuinit iucv_cpu_notify(struct notifier_block *self,
 		cpu_clear(cpu, cpumask);
 		if (cpus_empty(cpumask))
 			/* Can't offline last IUCV enabled cpu. */
-			return NOTIFY_BAD;
+			return notifier_from_errno(-EINVAL);
 		smp_call_function_single(cpu, iucv_retrieve_cpu, NULL, 1);
 		if (cpus_empty(iucv_irq_cpumask))
 			smp_call_function_single(first_cpu(iucv_buffer_cpumask),
-- 
1.6.0.6

[PATCH 09/12] ehca: convert cpu notifier to return encapsulate errno value

[Akinobu Mita]

By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for ehca.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Cc: Christoph Raisch <raisch@de.ibm.com>
Cc: linux-rdma@vger.kernel.org
---
 drivers/infiniband/hw/ehca/ehca_irq.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
index b2b6fea..31f3ee1 100644
--- a/drivers/infiniband/hw/ehca/ehca_irq.c
+++ b/drivers/infiniband/hw/ehca/ehca_irq.c
@@ -845,7 +845,7 @@ static int __cpuinit comp_pool_callback(struct notifier_block *nfb,
 		ehca_gen_dbg("CPU: %x (CPU_PREPARE)", cpu);
 		if (!create_comp_task(pool, cpu)) {
 			ehca_gen_err("Can't create comp_task for cpu: %x", cpu);
-			return NOTIFY_BAD;
+			return notifier_from_errno(-ENOMEM);
 		}
 		break;
 	case CPU_UP_CANCELED:
-- 
1.6.0.6

[PATCH 10/12] s390: convert cpu notifier to return encapsulate errno value

[Akinobu Mita]

By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for s390.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: linux-s390@vger.kernel.org
---
 arch/s390/kernel/smp.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 29f65bc..5c5ba7b 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -943,21 +943,21 @@ static int __cpuinit smp_cpu_notify(struct notifier_block *self,
 	struct cpu *c = &per_cpu(cpu_devices, cpu);
 	struct sys_device *s = &c->sysdev;
 	struct s390_idle_data *idle;
+	int err = 0;
 
 	switch (action) {
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
 		idle = &per_cpu(s390_idle, cpu);
 		memset(idle, 0, sizeof(struct s390_idle_data));
-		if (sysfs_create_group(&s->kobj, &cpu_online_attr_group))
-			return NOTIFY_BAD;
+		err = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
 		break;
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
 		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
 		break;
 	}
-	return NOTIFY_OK;
+	return notifier_from_errno(err);
 }
 
 static struct notifier_block __cpuinitdata smp_cpu_nb = {
-- 
1.6.0.6

[PATCH 11/12] md: convert cpu notifier to return encapsulate errno value

[Akinobu Mita]

By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for raid5.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
---
 drivers/md/raid5.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 70ffbd0..a711ba3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4659,7 +4659,7 @@ static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
 			kfree(percpu->scribble);
 			pr_err("%s: failed memory allocation for cpu%ld\n",
 			       __func__, cpu);
-			return NOTIFY_BAD;
+			return notifier_from_errno(-ENOMEM);
 		}
 		break;
 	case CPU_DEAD:
-- 
1.6.0.6

[PATCH 12/12] add CPU notifier error injection module

[Akinobu Mita]

I used this module to test the series of modification to the
cpu notifiers code.

Example1: inject CPU offline error (-1 == -EPERM)

	# modprobe cpu-notifier-error-inject cpu_down_prepare_error=-1
	# echo 0 > /sys/devices/system/cpu/cpu1/online0
	bash: echo: write error: Operation not permitted

Example2: inject CPU online error (-2 == -ENOENT)

	# modprobe cpu-notifier-error-inject cpu_up_prepare_error=-2
	# echo 1 > /sys/devices/system/cpu/cpu1/online0
	bash: echo: write error: No such file or directory

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 lib/Kconfig.debug               |   12 +++++++
 lib/Makefile                    |    1 +
 lib/cpu-notifier-error-inject.c |   63 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+), 0 deletions(-)
 create mode 100644 lib/cpu-notifier-error-inject.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8e5ec5e..ae467ed 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -885,6 +885,18 @@ config LKDTM
 	Documentation on how to use the module can be found in
 	Documentation/fault-injection/provoke-crashes.txt
 
+config CPU_NOTIFIER_ERROR_INJECT
+	tristate "CPU notifier error injection module"
+	depends on HOTPLUG_CPU && DEBUG_KERNEL
+	help
+	  This option provides a kernel module that can be used to test
+	  the error handling of the cpu notifiers
+
+	  To compile this code as a module, choose M here: the module will
+	  be called cpu-notify-inject.
+
+	  If unsure, say N.
+
 config FAULT_INJECTION
 	bool "Fault-injection framework"
 	depends on DEBUG_KERNEL
diff --git a/lib/Makefile b/lib/Makefile
index 2e152ae..9e34be2 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -82,6 +82,7 @@ obj-$(CONFIG_AUDIT_GENERIC) += audit.o
 obj-$(CONFIG_SWIOTLB) += swiotlb.o
 obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
 obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
+obj-$(CONFIG_CPU_NOTIFIER_ERROR_INJECT) += cpu-notifier-error-inject.o
 
 lib-$(CONFIG_GENERIC_BUG) += bug.o
 
diff --git a/lib/cpu-notifier-error-inject.c b/lib/cpu-notifier-error-inject.c
new file mode 100644
index 0000000..4dc2032
--- /dev/null
+++ b/lib/cpu-notifier-error-inject.c
@@ -0,0 +1,63 @@
+#include <linux/kernel.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+
+static int priority;
+static int cpu_up_prepare_error;
+static int cpu_down_prepare_error;
+
+module_param(priority, int, 0);
+MODULE_PARM_DESC(priority, "specify cpu notifier priority");
+
+module_param(cpu_up_prepare_error, int, 0644);
+MODULE_PARM_DESC(cpu_up_prepare_error,
+		"specify error code to inject CPU_UP_PREPARE action");
+
+module_param(cpu_down_prepare_error, int, 0644);
+MODULE_PARM_DESC(cpu_down_prepare_error,
+		"specify error code to inject CPU_DOWN_PREPARE action");
+
+static int err_inject_cpu_callback(struct notifier_block *nfb,
+				unsigned long action, void *hcpu)
+{
+	int err = 0;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		err = cpu_up_prepare_error;
+		break;
+	case CPU_DOWN_PREPARE:
+	case CPU_DOWN_PREPARE_FROZEN:
+		err = cpu_down_prepare_error;
+		break;
+	}
+	if (err)
+		printk(KERN_INFO "Injecting error (%d) at cpu notifier\n", err);
+
+	return notifier_from_errno(err);
+}
+
+static struct notifier_block err_inject_cpu_notifier = {
+	.notifier_call = err_inject_cpu_callback,
+};
+
+static int err_inject_init(void)
+{
+	err_inject_cpu_notifier.priority = priority;
+
+	return register_hotcpu_notifier(&err_inject_cpu_notifier);
+}
+
+static void err_inject_exit(void)
+{
+	unregister_hotcpu_notifier(&err_inject_cpu_notifier);
+}
+
+module_init(err_inject_init);
+module_exit(err_inject_exit);
+
+MODULE_DESCRIPTION("CPU notifier error injection module");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
-- 
1.6.0.6

Re: [PATCH 07/12] slab: convert cpu notifier to return encapsulate errno value

[Pekka Enberg]

On Thu, Mar 18, 2010 at 11:05 AM, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> By the previous modification, the cpu notifier can return encapsulate
> errno value. This converts the cpu notifiers for slab.
>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: Christoph Lameter <cl@linux-foundation.org>

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

> Cc: Matt Mackall <mpm@selenic.com>
> Cc: linux-mm@kvack.org
> ---
>  mm/slab.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/slab.c b/mm/slab.c
> index a9f325b..d57309e 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -1324,7 +1324,7 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
>                mutex_unlock(&cache_chain_mutex);
>                break;
>        }
> -       return err ? NOTIFY_BAD : NOTIFY_OK;
> +       return notifier_from_errno(err);
>  }
>
>  static struct notifier_block __cpuinitdata cpucache_notifier = {
> --
> 1.6.0.6
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>

Re: [PATCH 12/12] add CPU notifier error injection module

[Andrew Morton]

On Thu, 18 Mar 2010 18:05:24 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:

> I used this module to test the series of modification to the
> cpu notifiers code.
> 
> Example1: inject CPU offline error (-1 == -EPERM)
> 
> 	# modprobe cpu-notifier-error-inject cpu_down_prepare_error=-1
> 	# echo 0 > /sys/devices/system/cpu/cpu1/online0
> 	bash: echo: write error: Operation not permitted
> 
> Example2: inject CPU online error (-2 == -ENOENT)
> 
> 	# modprobe cpu-notifier-error-inject cpu_up_prepare_error=-2
> 	# echo 1 > /sys/devices/system/cpu/cpu1/online0
> 	bash: echo: write error: No such file or directory
> 
> ...
>
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -885,6 +885,18 @@ config LKDTM
>  	Documentation on how to use the module can be found in
>  	Documentation/fault-injection/provoke-crashes.txt
>  
> +config CPU_NOTIFIER_ERROR_INJECT
> +	tristate "CPU notifier error injection module"
> +	depends on HOTPLUG_CPU && DEBUG_KERNEL
> +	help
> +	  This option provides a kernel module that can be used to test
> +	  the error handling of the cpu notifiers
> +
> +	  To compile this code as a module, choose M here: the module will
> +	  be called cpu-notify-inject.

Should be "cpu-notifier-error-inject", yes?

> +	  If unsure, say N.
> +
>  config FAULT_INJECTION
>  	bool "Fault-injection framework"
>  	depends on DEBUG_KERNEL

Re: [PATCH 12/12] add CPU notifier error injection module

[Akinobu Mita]

2010/3/23 Andrew Morton <akpm@linux-foundation.org>:
> On Thu, 18 Mar 2010 18:05:24 +0900
> Akinobu Mita <akinobu.mita@gmail.com> wrote:
>
>> I used this module to test the series of modification to the
>> cpu notifiers code.
>>
>> Example1: inject CPU offline error (-1 == -EPERM)
>>
>>       # modprobe cpu-notifier-error-inject cpu_down_prepare_error=-1
>>       # echo 0 > /sys/devices/system/cpu/cpu1/online0
>>       bash: echo: write error: Operation not permitted
>>
>> Example2: inject CPU online error (-2 == -ENOENT)
>>
>>       # modprobe cpu-notifier-error-inject cpu_up_prepare_error=-2
>>       # echo 1 > /sys/devices/system/cpu/cpu1/online0
>>       bash: echo: write error: No such file or directory
>>
>> ...
>>
>> --- a/lib/Kconfig.debug
>> +++ b/lib/Kconfig.debug
>> @@ -885,6 +885,18 @@ config LKDTM
>>       Documentation on how to use the module can be found in
>>       Documentation/fault-injection/provoke-crashes.txt
>>
>> +config CPU_NOTIFIER_ERROR_INJECT
>> +     tristate "CPU notifier error injection module"
>> +     depends on HOTPLUG_CPU && DEBUG_KERNEL
>> +     help
>> +       This option provides a kernel module that can be used to test
>> +       the error handling of the cpu notifiers
>> +
>> +       To compile this code as a module, choose M here: the module will
>> +       be called cpu-notify-inject.
>
> Should be "cpu-notifier-error-inject", yes?

Yes. Thanks for spotting and fixing.
And I had another typos in the above patch description:

>> Example1: inject CPU offline error (-1 == -EPERM)
>>
>>       # modprobe cpu-notifier-error-inject cpu_down_prepare_error=-1
>>       # echo 0 > /sys/devices/system/cpu/cpu1/online0

# echo 0 > /sys/devices/system/cpu/cpu1/online

(s/online0/online/)

>>       bash: echo: write error: Operation not permitted
>>
>> Example2: inject CPU online error (-2 == -ENOENT)
>>
>>       # modprobe cpu-notifier-error-inject cpu_up_prepare_error=-2
>>       # echo 1 > /sys/devices/system/cpu/cpu1/online0

Ditto.

>>       bash: echo: write error: No such file or directory

Re: [PATCH 09/12] ehca: convert cpu notifier to return encapsulate errno value

[Alexander Schmidt]

On Thu, 18 Mar 2010 18:05:21 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:

> By the previous modification, the cpu notifier can return encapsulate
> errno value. This converts the cpu notifiers for ehca.
> 
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
> Cc: Christoph Raisch <raisch@de.ibm.com>
> Cc: linux-rdma@vger.kernel.org

Acked-by: Alexander Schmidt <alexs@linux.vnet.ibm.com>

> ---
>  drivers/infiniband/hw/ehca/ehca_irq.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
> index b2b6fea..31f3ee1 100644
> --- a/drivers/infiniband/hw/ehca/ehca_irq.c
> +++ b/drivers/infiniband/hw/ehca/ehca_irq.c
> @@ -845,7 +845,7 @@ static int __cpuinit comp_pool_callback(struct notifier_block *nfb,
>  		ehca_gen_dbg("CPU: %x (CPU_PREPARE)", cpu);
>  		if (!create_comp_task(pool, cpu)) {
>  			ehca_gen_err("Can't create comp_task for cpu: %x", cpu);
> -			return NOTIFY_BAD;
> +			return notifier_from_errno(-ENOMEM);
>  		}
>  		break;
>  	case CPU_UP_CANCELED: