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* [PATCH] cpu/SMT: fix x86 link error without CONFIG_SYSFS
@ 2019-12-10 19:56 Arnd Bergmann
  2019-12-10 20:12 ` Jiri Kosina
  2020-01-09 16:36 ` [tip: smp/urgent] cpu/SMT: Fix " tip-bot2 for Arnd Bergmann
  0 siblings, 2 replies; 5+ messages in thread
From: Arnd Bergmann @ 2019-12-10 19:56 UTC (permalink / raw)
  To: Thomas Gleixner, Pavel Machek, Josh Poimboeuf, Jiri Kosina,
	Rafael J. Wysocki
  Cc: Arnd Bergmann, stable, Peter Zijlstra (Intel),
	Ingo Molnar, Valentin Schneider, Zhenzhong Duan, Tyler Hicks,
	linux-kernel

When CONFIG_SYSFS is disabled, but CONFIG_HOTPLUG_SMT is enabled,
the kernel fails to link:

arch/x86/power/cpu.o: In function `hibernate_resume_nonboot_cpu_disable':
(.text+0x38d): undefined reference to `cpuhp_smt_enable'
arch/x86/power/hibernate.o: In function `arch_resume_nosmt':
hibernate.c:(.text+0x291): undefined reference to `cpuhp_smt_enable'
hibernate.c:(.text+0x29c): undefined reference to `cpuhp_smt_disable'

Move the exported functions out of the #ifdef section into its
own with the correct conditions.

The patch that caused this is marked for stable backports, so
this one may need to be backported as well.

Fixes: ec527c318036 ("x86/power: Fix 'nosmt' vs hibernation triple fault during resume")
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/cpu.c | 143 ++++++++++++++++++++++++++-------------------------
 1 file changed, 72 insertions(+), 71 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index a59cc980adad..4dc279ed3b2d 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1909,6 +1909,78 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
 }
 EXPORT_SYMBOL(__cpuhp_remove_state);
 
+#ifdef CONFIG_HOTPLUG_SMT
+static void cpuhp_offline_cpu_device(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+
+	dev->offline = true;
+	/* Tell user space about the state change */
+	kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
+}
+
+static void cpuhp_online_cpu_device(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+
+	dev->offline = false;
+	/* Tell user space about the state change */
+	kobject_uevent(&dev->kobj, KOBJ_ONLINE);
+}
+
+int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
+{
+	int cpu, ret = 0;
+
+	cpu_maps_update_begin();
+	for_each_online_cpu(cpu) {
+		if (topology_is_primary_thread(cpu))
+			continue;
+		ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
+		if (ret)
+			break;
+		/*
+		 * As this needs to hold the cpu maps lock it's impossible
+		 * to call device_offline() because that ends up calling
+		 * cpu_down() which takes cpu maps lock. cpu maps lock
+		 * needs to be held as this might race against in kernel
+		 * abusers of the hotplug machinery (thermal management).
+		 *
+		 * So nothing would update device:offline state. That would
+		 * leave the sysfs entry stale and prevent onlining after
+		 * smt control has been changed to 'off' again. This is
+		 * called under the sysfs hotplug lock, so it is properly
+		 * serialized against the regular offline usage.
+		 */
+		cpuhp_offline_cpu_device(cpu);
+	}
+	if (!ret)
+		cpu_smt_control = ctrlval;
+	cpu_maps_update_done();
+	return ret;
+}
+
+int cpuhp_smt_enable(void)
+{
+	int cpu, ret = 0;
+
+	cpu_maps_update_begin();
+	cpu_smt_control = CPU_SMT_ENABLED;
+	for_each_present_cpu(cpu) {
+		/* Skip online CPUs and CPUs on offline nodes */
+		if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
+			continue;
+		ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
+		if (ret)
+			break;
+		/* See comment in cpuhp_smt_disable() */
+		cpuhp_online_cpu_device(cpu);
+	}
+	cpu_maps_update_done();
+	return ret;
+}
+#endif
+
 #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
 static ssize_t show_cpuhp_state(struct device *dev,
 				struct device_attribute *attr, char *buf)
@@ -2063,77 +2135,6 @@ static const struct attribute_group cpuhp_cpu_root_attr_group = {
 
 #ifdef CONFIG_HOTPLUG_SMT
 
-static void cpuhp_offline_cpu_device(unsigned int cpu)
-{
-	struct device *dev = get_cpu_device(cpu);
-
-	dev->offline = true;
-	/* Tell user space about the state change */
-	kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
-}
-
-static void cpuhp_online_cpu_device(unsigned int cpu)
-{
-	struct device *dev = get_cpu_device(cpu);
-
-	dev->offline = false;
-	/* Tell user space about the state change */
-	kobject_uevent(&dev->kobj, KOBJ_ONLINE);
-}
-
-int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
-{
-	int cpu, ret = 0;
-
-	cpu_maps_update_begin();
-	for_each_online_cpu(cpu) {
-		if (topology_is_primary_thread(cpu))
-			continue;
-		ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
-		if (ret)
-			break;
-		/*
-		 * As this needs to hold the cpu maps lock it's impossible
-		 * to call device_offline() because that ends up calling
-		 * cpu_down() which takes cpu maps lock. cpu maps lock
-		 * needs to be held as this might race against in kernel
-		 * abusers of the hotplug machinery (thermal management).
-		 *
-		 * So nothing would update device:offline state. That would
-		 * leave the sysfs entry stale and prevent onlining after
-		 * smt control has been changed to 'off' again. This is
-		 * called under the sysfs hotplug lock, so it is properly
-		 * serialized against the regular offline usage.
-		 */
-		cpuhp_offline_cpu_device(cpu);
-	}
-	if (!ret)
-		cpu_smt_control = ctrlval;
-	cpu_maps_update_done();
-	return ret;
-}
-
-int cpuhp_smt_enable(void)
-{
-	int cpu, ret = 0;
-
-	cpu_maps_update_begin();
-	cpu_smt_control = CPU_SMT_ENABLED;
-	for_each_present_cpu(cpu) {
-		/* Skip online CPUs and CPUs on offline nodes */
-		if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
-			continue;
-		ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
-		if (ret)
-			break;
-		/* See comment in cpuhp_smt_disable() */
-		cpuhp_online_cpu_device(cpu);
-	}
-	cpu_maps_update_done();
-	return ret;
-}
-
-
 static ssize_t
 __store_smt_control(struct device *dev, struct device_attribute *attr,
 		    const char *buf, size_t count)
-- 
2.20.0


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] cpu/SMT: fix x86 link error without CONFIG_SYSFS
  2019-12-10 19:56 [PATCH] cpu/SMT: fix x86 link error without CONFIG_SYSFS Arnd Bergmann
@ 2019-12-10 20:12 ` Jiri Kosina
  2019-12-20 22:01   ` Jiri Kosina
  2020-01-09 16:36 ` [tip: smp/urgent] cpu/SMT: Fix " tip-bot2 for Arnd Bergmann
  1 sibling, 1 reply; 5+ messages in thread
From: Jiri Kosina @ 2019-12-10 20:12 UTC (permalink / raw)
  To: Arnd Bergmann
  Cc: Thomas Gleixner, Pavel Machek, Josh Poimboeuf, Rafael J. Wysocki,
	stable, Peter Zijlstra (Intel),
	Ingo Molnar, Valentin Schneider, Zhenzhong Duan, Tyler Hicks,
	linux-kernel

On Tue, 10 Dec 2019, Arnd Bergmann wrote:

> When CONFIG_SYSFS is disabled, but CONFIG_HOTPLUG_SMT is enabled,
> the kernel fails to link:

I wonder where such kernels are running ... or I rather don't :)

> arch/x86/power/cpu.o: In function `hibernate_resume_nonboot_cpu_disable':
> (.text+0x38d): undefined reference to `cpuhp_smt_enable'
> arch/x86/power/hibernate.o: In function `arch_resume_nosmt':
> hibernate.c:(.text+0x291): undefined reference to `cpuhp_smt_enable'
> hibernate.c:(.text+0x29c): undefined reference to `cpuhp_smt_disable'
> 
> Move the exported functions out of the #ifdef section into its
> own with the correct conditions.
> 
> The patch that caused this is marked for stable backports, so
> this one may need to be backported as well.
> 
> Fixes: ec527c318036 ("x86/power: Fix 'nosmt' vs hibernation triple fault during resume")

Reviewed-by: Jiri Kosina <jkosina@suse.cz>

Thanks for fixing my oversight.

-- 
Jiri Kosina
SUSE Labs


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] cpu/SMT: fix x86 link error without CONFIG_SYSFS
  2019-12-10 20:12 ` Jiri Kosina
@ 2019-12-20 22:01   ` Jiri Kosina
  0 siblings, 0 replies; 5+ messages in thread
From: Jiri Kosina @ 2019-12-20 22:01 UTC (permalink / raw)
  To: Arnd Bergmann
  Cc: Thomas Gleixner, Pavel Machek, Josh Poimboeuf, Rafael J. Wysocki,
	stable, Peter Zijlstra (Intel),
	Ingo Molnar, Valentin Schneider, Zhenzhong Duan, Tyler Hicks,
	linux-kernel

On Tue, 10 Dec 2019, Jiri Kosina wrote:

> > When CONFIG_SYSFS is disabled, but CONFIG_HOTPLUG_SMT is enabled,
> > the kernel fails to link:
> 
> I wonder where such kernels are running ... or I rather don't :)
> 
> > arch/x86/power/cpu.o: In function `hibernate_resume_nonboot_cpu_disable':
> > (.text+0x38d): undefined reference to `cpuhp_smt_enable'
> > arch/x86/power/hibernate.o: In function `arch_resume_nosmt':
> > hibernate.c:(.text+0x291): undefined reference to `cpuhp_smt_enable'
> > hibernate.c:(.text+0x29c): undefined reference to `cpuhp_smt_disable'
> > 
> > Move the exported functions out of the #ifdef section into its
> > own with the correct conditions.
> > 
> > The patch that caused this is marked for stable backports, so
> > this one may need to be backported as well.
> > 
> > Fixes: ec527c318036 ("x86/power: Fix 'nosmt' vs hibernation triple fault during resume")
> 
> Reviewed-by: Jiri Kosina <jkosina@suse.cz>
> 
> Thanks for fixing my oversight.

Is anyone going to pick this up please?

Thanks,

-- 
Jiri Kosina
SUSE Labs


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [tip: smp/urgent] cpu/SMT: Fix x86 link error without CONFIG_SYSFS
  2019-12-10 19:56 [PATCH] cpu/SMT: fix x86 link error without CONFIG_SYSFS Arnd Bergmann
  2019-12-10 20:12 ` Jiri Kosina
@ 2020-01-09 16:36 ` " tip-bot2 for Arnd Bergmann
       [not found]   ` <20200114130955.2EAC824685@mail.kernel.org>
  1 sibling, 1 reply; 5+ messages in thread
From: tip-bot2 for Arnd Bergmann @ 2020-01-09 16:36 UTC (permalink / raw)
  To: linux-tip-commits
  Cc: Arnd Bergmann, Thomas Gleixner, Jiri Kosina, stable, x86, LKML

The following commit has been merged into the smp/urgent branch of tip:

Commit-ID:     dc8d37ed304eeeea47e65fb9edc1c6c8b0093386
Gitweb:        https://git.kernel.org/tip/dc8d37ed304eeeea47e65fb9edc1c6c8b0093386
Author:        Arnd Bergmann <arnd@arndb.de>
AuthorDate:    Tue, 10 Dec 2019 20:56:04 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 09 Jan 2020 17:31:45 +01:00

cpu/SMT: Fix x86 link error without CONFIG_SYSFS

When CONFIG_SYSFS is disabled, but CONFIG_HOTPLUG_SMT is enabled,
the kernel fails to link:

arch/x86/power/cpu.o: In function `hibernate_resume_nonboot_cpu_disable':
(.text+0x38d): undefined reference to `cpuhp_smt_enable'
arch/x86/power/hibernate.o: In function `arch_resume_nosmt':
hibernate.c:(.text+0x291): undefined reference to `cpuhp_smt_enable'
hibernate.c:(.text+0x29c): undefined reference to `cpuhp_smt_disable'

Move the exported functions out of the #ifdef section into its
own with the correct conditions.

The patch that caused this is marked for stable backports, so
this one may need to be backported as well.

Fixes: ec527c318036 ("x86/power: Fix 'nosmt' vs hibernation triple fault during resume")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jiri Kosina <jkosina@suse.cz>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191210195614.786555-1-arnd@arndb.de

---
 kernel/cpu.c | 143 +++++++++++++++++++++++++-------------------------
 1 file changed, 72 insertions(+), 71 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index a59cc98..4dc279e 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1909,6 +1909,78 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
 }
 EXPORT_SYMBOL(__cpuhp_remove_state);
 
+#ifdef CONFIG_HOTPLUG_SMT
+static void cpuhp_offline_cpu_device(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+
+	dev->offline = true;
+	/* Tell user space about the state change */
+	kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
+}
+
+static void cpuhp_online_cpu_device(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+
+	dev->offline = false;
+	/* Tell user space about the state change */
+	kobject_uevent(&dev->kobj, KOBJ_ONLINE);
+}
+
+int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
+{
+	int cpu, ret = 0;
+
+	cpu_maps_update_begin();
+	for_each_online_cpu(cpu) {
+		if (topology_is_primary_thread(cpu))
+			continue;
+		ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
+		if (ret)
+			break;
+		/*
+		 * As this needs to hold the cpu maps lock it's impossible
+		 * to call device_offline() because that ends up calling
+		 * cpu_down() which takes cpu maps lock. cpu maps lock
+		 * needs to be held as this might race against in kernel
+		 * abusers of the hotplug machinery (thermal management).
+		 *
+		 * So nothing would update device:offline state. That would
+		 * leave the sysfs entry stale and prevent onlining after
+		 * smt control has been changed to 'off' again. This is
+		 * called under the sysfs hotplug lock, so it is properly
+		 * serialized against the regular offline usage.
+		 */
+		cpuhp_offline_cpu_device(cpu);
+	}
+	if (!ret)
+		cpu_smt_control = ctrlval;
+	cpu_maps_update_done();
+	return ret;
+}
+
+int cpuhp_smt_enable(void)
+{
+	int cpu, ret = 0;
+
+	cpu_maps_update_begin();
+	cpu_smt_control = CPU_SMT_ENABLED;
+	for_each_present_cpu(cpu) {
+		/* Skip online CPUs and CPUs on offline nodes */
+		if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
+			continue;
+		ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
+		if (ret)
+			break;
+		/* See comment in cpuhp_smt_disable() */
+		cpuhp_online_cpu_device(cpu);
+	}
+	cpu_maps_update_done();
+	return ret;
+}
+#endif
+
 #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
 static ssize_t show_cpuhp_state(struct device *dev,
 				struct device_attribute *attr, char *buf)
@@ -2063,77 +2135,6 @@ static const struct attribute_group cpuhp_cpu_root_attr_group = {
 
 #ifdef CONFIG_HOTPLUG_SMT
 
-static void cpuhp_offline_cpu_device(unsigned int cpu)
-{
-	struct device *dev = get_cpu_device(cpu);
-
-	dev->offline = true;
-	/* Tell user space about the state change */
-	kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
-}
-
-static void cpuhp_online_cpu_device(unsigned int cpu)
-{
-	struct device *dev = get_cpu_device(cpu);
-
-	dev->offline = false;
-	/* Tell user space about the state change */
-	kobject_uevent(&dev->kobj, KOBJ_ONLINE);
-}
-
-int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
-{
-	int cpu, ret = 0;
-
-	cpu_maps_update_begin();
-	for_each_online_cpu(cpu) {
-		if (topology_is_primary_thread(cpu))
-			continue;
-		ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
-		if (ret)
-			break;
-		/*
-		 * As this needs to hold the cpu maps lock it's impossible
-		 * to call device_offline() because that ends up calling
-		 * cpu_down() which takes cpu maps lock. cpu maps lock
-		 * needs to be held as this might race against in kernel
-		 * abusers of the hotplug machinery (thermal management).
-		 *
-		 * So nothing would update device:offline state. That would
-		 * leave the sysfs entry stale and prevent onlining after
-		 * smt control has been changed to 'off' again. This is
-		 * called under the sysfs hotplug lock, so it is properly
-		 * serialized against the regular offline usage.
-		 */
-		cpuhp_offline_cpu_device(cpu);
-	}
-	if (!ret)
-		cpu_smt_control = ctrlval;
-	cpu_maps_update_done();
-	return ret;
-}
-
-int cpuhp_smt_enable(void)
-{
-	int cpu, ret = 0;
-
-	cpu_maps_update_begin();
-	cpu_smt_control = CPU_SMT_ENABLED;
-	for_each_present_cpu(cpu) {
-		/* Skip online CPUs and CPUs on offline nodes */
-		if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
-			continue;
-		ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
-		if (ret)
-			break;
-		/* See comment in cpuhp_smt_disable() */
-		cpuhp_online_cpu_device(cpu);
-	}
-	cpu_maps_update_done();
-	return ret;
-}
-
-
 static ssize_t
 __store_smt_control(struct device *dev, struct device_attribute *attr,
 		    const char *buf, size_t count)

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [tip: smp/urgent] cpu/SMT: Fix x86 link error without CONFIG_SYSFS
       [not found]   ` <20200114130955.2EAC824685@mail.kernel.org>
@ 2020-01-14 13:25     ` Arnd Bergmann
  0 siblings, 0 replies; 5+ messages in thread
From: Arnd Bergmann @ 2020-01-14 13:25 UTC (permalink / raw)
  To: Sasha Levin; +Cc: tip-bot2 for Arnd Bergmann, linux-tip-commits, # 3.4.x

On Tue, Jan 14, 2020 at 2:09 PM Sasha Levin <sashal@kernel.org> wrote:
>
> Hi,
>
> [This is an automated email]
>
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: ec527c318036 ("x86/power: Fix 'nosmt' vs hibernation triple fault during resume").
>
> The bot has tested the following trees: v5.4.11, v4.19.95, v4.14.164, v4.9.209.
>
> v5.4.11: Build OK!
> v4.19.95: Failed to apply! Possible dependencies:
>     34d66caf251d ("x86/speculation: Remove redundant arch_smt_update() invocation")
>     de7b77e5bb94 ("cpu/hotplug: Create SMT sysfs interface for all arches")
>
> v4.14.164: Failed to apply! Possible dependencies:
>     34d66caf251d ("x86/speculation: Remove redundant arch_smt_update() invocation")
>     de7b77e5bb94 ("cpu/hotplug: Create SMT sysfs interface for all arches")
>
> v4.9.209: Failed to apply! Possible dependencies:
>     34d66caf251d ("x86/speculation: Remove redundant arch_smt_update() invocation")
>     de7b77e5bb94 ("cpu/hotplug: Create SMT sysfs interface for all arches")
>
>
> NOTE: The patch will not be queued to stable trees until it is upstream.
>
> How should we proceed with this patch?

According to the changelog text, the patch is only needed on v5.2 and
higher, so this
is all good.

        Arnd

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, back to index

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-12-10 19:56 [PATCH] cpu/SMT: fix x86 link error without CONFIG_SYSFS Arnd Bergmann
2019-12-10 20:12 ` Jiri Kosina
2019-12-20 22:01   ` Jiri Kosina
2020-01-09 16:36 ` [tip: smp/urgent] cpu/SMT: Fix " tip-bot2 for Arnd Bergmann
     [not found]   ` <20200114130955.2EAC824685@mail.kernel.org>
2020-01-14 13:25     ` Arnd Bergmann

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