Patchwork [4/4] hotplug, powerpc, x86: Remove cpu_hotplug_driver_lock()

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Submitter Toshi Kani
Date Aug. 17, 2013, 7:46 p.m.
Message ID <1376768819-28975-5-git-send-email-toshi.kani@hp.com>
Download mbox | patch
Permalink /patch/267998/
State Not Applicable
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Comments

Toshi Kani - Aug. 17, 2013, 7:46 p.m.
cpu_hotplug_driver_lock() serializes CPU online/offline operations
when ARCH_CPU_PROBE_RELEASE is set.  This lock interface is no longer
necessary with the following reason:

 - lock_device_hotplug() now protects CPU online/offline operations,
   including the probe & release interfaces enabled by
   ARCH_CPU_PROBE_RELEASE.  The use of cpu_hotplug_driver_lock() is
   redundant.
 - cpu_hotplug_driver_lock() is only valid when ARCH_CPU_PROBE_RELEASE
   is defined, which is misleading and is only enabled on powerpc.

This patch removes the cpu_hotplug_driver_lock() interface.  As
a result, ARCH_CPU_PROBE_RELEASE only enables / disables the cpu
probe & release interface as intended.  There is no functional change
in this patch.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
---
Performed build test only on powerpc.
---
 arch/powerpc/kernel/smp.c              |   12 ----------
 arch/powerpc/platforms/pseries/dlpar.c |   40 ++++++++++++--------------------
 arch/x86/kernel/topology.c             |    2 --
 drivers/base/cpu.c                     |   10 +-------
 include/linux/cpu.h                    |   13 ----------
 5 files changed, 16 insertions(+), 61 deletions(-)
Rafael J. Wysocki - Aug. 18, 2013, 1:01 a.m.
On Saturday, August 17, 2013 01:46:59 PM Toshi Kani wrote:
> cpu_hotplug_driver_lock() serializes CPU online/offline operations
> when ARCH_CPU_PROBE_RELEASE is set.  This lock interface is no longer
> necessary with the following reason:
> 
>  - lock_device_hotplug() now protects CPU online/offline operations,
>    including the probe & release interfaces enabled by
>    ARCH_CPU_PROBE_RELEASE.  The use of cpu_hotplug_driver_lock() is
>    redundant.
>  - cpu_hotplug_driver_lock() is only valid when ARCH_CPU_PROBE_RELEASE
>    is defined, which is misleading and is only enabled on powerpc.
> 
> This patch removes the cpu_hotplug_driver_lock() interface.  As
> a result, ARCH_CPU_PROBE_RELEASE only enables / disables the cpu
> probe & release interface as intended.  There is no functional change
> in this patch.
> 
> Signed-off-by: Toshi Kani <toshi.kani@hp.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
> Performed build test only on powerpc.
> ---
>  arch/powerpc/kernel/smp.c              |   12 ----------
>  arch/powerpc/platforms/pseries/dlpar.c |   40 ++++++++++++--------------------
>  arch/x86/kernel/topology.c             |    2 --
>  drivers/base/cpu.c                     |   10 +-------
>  include/linux/cpu.h                    |   13 ----------
>  5 files changed, 16 insertions(+), 61 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index 38b0ba6..1667269 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -763,18 +763,6 @@ void __cpu_die(unsigned int cpu)
>  		smp_ops->cpu_die(cpu);
>  }
>  
> -static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);
> -
> -void cpu_hotplug_driver_lock()
> -{
> -	mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
> -}
> -
> -void cpu_hotplug_driver_unlock()
> -{
> -	mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
> -}
> -
>  void cpu_die(void)
>  {
>  	if (ppc_md.cpu_die)
> diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
> index a1a7b9a..e39325d 100644
> --- a/arch/powerpc/platforms/pseries/dlpar.c
> +++ b/arch/powerpc/platforms/pseries/dlpar.c
> @@ -387,18 +387,13 @@ 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) {
> -		rc = -EINVAL;
> -		goto out;
> -	}
> +	if (rc)
> +		return -EINVAL;
>  
>  	dn = dlpar_configure_connector(drc_index);
> -	if (!dn) {
> -		rc = -EINVAL;
> -		goto out;
> -	}
> +	if (!dn)
> +		return -EINVAL;
>  
>  	/* configure-connector reports cpus as living in the base
>  	 * directory of the device tree.  CPUs actually live in the
> @@ -407,8 +402,7 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
>  	cpu_name = kasprintf(GFP_KERNEL, "/cpus%s", dn->full_name);
>  	if (!cpu_name) {
>  		dlpar_free_cc_nodes(dn);
> -		rc = -ENOMEM;
> -		goto out;
> +		return -ENOMEM;
>  	}
>  
>  	kfree(dn->full_name);
> @@ -417,22 +411,21 @@ 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);
> -		rc = -EINVAL;
> -		goto out;
> +		return -EINVAL;
>  	}
>  
>  	rc = dlpar_attach_node(dn);
>  	if (rc) {
>  		dlpar_release_drc(drc_index);
>  		dlpar_free_cc_nodes(dn);
> -		goto out;
> +		return rc;
>  	}
>  
>  	rc = dlpar_online_cpu(dn);
> -out:
> -	cpu_hotplug_driver_unlock();
> +	if (rc)
> +		return rc;
>  
> -	return rc ? rc : count;
> +	return count;
>  }
>  
>  static int dlpar_offline_cpu(struct device_node *dn)
> @@ -505,30 +498,27 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t count)
>  		return -EINVAL;
>  	}
>  
> -	cpu_hotplug_driver_lock();
>  	rc = dlpar_offline_cpu(dn);
>  	if (rc) {
>  		of_node_put(dn);
> -		rc = -EINVAL;
> -		goto out;
> +		return -EINVAL;
>  	}
>  
>  	rc = dlpar_release_drc(*drc_index);
>  	if (rc) {
>  		of_node_put(dn);
> -		goto out;
> +		return rc;
>  	}
>  
>  	rc = dlpar_detach_node(dn);
>  	if (rc) {
>  		dlpar_acquire_drc(*drc_index);
> -		goto out;
> +		return rc;
>  	}
>  
>  	of_node_put(dn);
> -out:
> -	cpu_hotplug_driver_unlock();
> -	return rc ? rc : count;
> +
> +	return count;
>  }
>  
>  static int __init pseries_dlpar_init(void)
> diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
> index a3f35eb..649b010 100644
> --- a/arch/x86/kernel/topology.c
> +++ b/arch/x86/kernel/topology.c
> @@ -66,7 +66,6 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
>  		return -EINVAL;
>  
>  	lock_device_hotplug();
> -	cpu_hotplug_driver_lock();
>  
>  	switch (action) {
>  	case 0:
> @@ -91,7 +90,6 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
>  		ret = -EINVAL;
>  	}
>  
> -	cpu_hotplug_driver_unlock();
>  	unlock_device_hotplug();
>  
>  	return ret;
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index 4cc6928..b4ebd7b 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -45,8 +45,6 @@ static int __ref cpu_subsys_online(struct device *dev)
>  	int from_nid, to_nid;
>  	int ret;
>  
> -	cpu_hotplug_driver_lock();
> -
>  	from_nid = cpu_to_node(cpuid);
>  	ret = cpu_up(cpuid);
>  	/*
> @@ -57,18 +55,12 @@ static int __ref cpu_subsys_online(struct device *dev)
>  	if (from_nid != to_nid)
>  		change_cpu_under_node(cpu, from_nid, to_nid);
>  
> -	cpu_hotplug_driver_unlock();
>  	return ret;
>  }
>  
>  static int cpu_subsys_offline(struct device *dev)
>  {
> -	int ret;
> -
> -	cpu_hotplug_driver_lock();
> -	ret = cpu_down(dev->id);
> -	cpu_hotplug_driver_unlock();
> -	return ret;
> +	return cpu_down(dev->id);
>  }
>  
>  void unregister_cpu(struct cpu *cpu)
> diff --git a/include/linux/cpu.h b/include/linux/cpu.h
> index ab0eade..e847ef8 100644
> --- a/include/linux/cpu.h
> +++ b/include/linux/cpu.h
> @@ -182,19 +182,6 @@ extern void cpu_hotplug_enable(void);
>  void clear_tasks_mm_cpumask(int cpu);
>  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)
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
Nathan Fontenot - Aug. 19, 2013, 3:20 p.m.
On 08/17/2013 02:46 PM, Toshi Kani wrote:
> cpu_hotplug_driver_lock() serializes CPU online/offline operations
> when ARCH_CPU_PROBE_RELEASE is set.  This lock interface is no longer
> necessary with the following reason:
> 
>  - lock_device_hotplug() now protects CPU online/offline operations,
>    including the probe & release interfaces enabled by
>    ARCH_CPU_PROBE_RELEASE.  The use of cpu_hotplug_driver_lock() is
>    redundant.
>  - cpu_hotplug_driver_lock() is only valid when ARCH_CPU_PROBE_RELEASE
>    is defined, which is misleading and is only enabled on powerpc.
> 
> This patch removes the cpu_hotplug_driver_lock() interface.  As
> a result, ARCH_CPU_PROBE_RELEASE only enables / disables the cpu
> probe & release interface as intended.  There is no functional change
> in this patch.
> 
> Signed-off-by: Toshi Kani <toshi.kani@hp.com>

Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>

> ---
> Performed build test only on powerpc.
> ---
>  arch/powerpc/kernel/smp.c              |   12 ----------
>  arch/powerpc/platforms/pseries/dlpar.c |   40 ++++++++++++--------------------
>  arch/x86/kernel/topology.c             |    2 --
>  drivers/base/cpu.c                     |   10 +-------
>  include/linux/cpu.h                    |   13 ----------
>  5 files changed, 16 insertions(+), 61 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index 38b0ba6..1667269 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -763,18 +763,6 @@ void __cpu_die(unsigned int cpu)
>  		smp_ops->cpu_die(cpu);
>  }
>  
> -static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);
> -
> -void cpu_hotplug_driver_lock()
> -{
> -	mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
> -}
> -
> -void cpu_hotplug_driver_unlock()
> -{
> -	mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
> -}
> -
>  void cpu_die(void)
>  {
>  	if (ppc_md.cpu_die)
> diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
> index a1a7b9a..e39325d 100644
> --- a/arch/powerpc/platforms/pseries/dlpar.c
> +++ b/arch/powerpc/platforms/pseries/dlpar.c
> @@ -387,18 +387,13 @@ 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) {
> -		rc = -EINVAL;
> -		goto out;
> -	}
> +	if (rc)
> +		return -EINVAL;
>  
>  	dn = dlpar_configure_connector(drc_index);
> -	if (!dn) {
> -		rc = -EINVAL;
> -		goto out;
> -	}
> +	if (!dn)
> +		return -EINVAL;
>  
>  	/* configure-connector reports cpus as living in the base
>  	 * directory of the device tree.  CPUs actually live in the
> @@ -407,8 +402,7 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
>  	cpu_name = kasprintf(GFP_KERNEL, "/cpus%s", dn->full_name);
>  	if (!cpu_name) {
>  		dlpar_free_cc_nodes(dn);
> -		rc = -ENOMEM;
> -		goto out;
> +		return -ENOMEM;
>  	}
>  
>  	kfree(dn->full_name);
> @@ -417,22 +411,21 @@ 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);
> -		rc = -EINVAL;
> -		goto out;
> +		return -EINVAL;
>  	}
>  
>  	rc = dlpar_attach_node(dn);
>  	if (rc) {
>  		dlpar_release_drc(drc_index);
>  		dlpar_free_cc_nodes(dn);
> -		goto out;
> +		return rc;
>  	}
>  
>  	rc = dlpar_online_cpu(dn);
> -out:
> -	cpu_hotplug_driver_unlock();
> +	if (rc)
> +		return rc;
>  
> -	return rc ? rc : count;
> +	return count;
>  }
>  
>  static int dlpar_offline_cpu(struct device_node *dn)
> @@ -505,30 +498,27 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t count)
>  		return -EINVAL;
>  	}
>  
> -	cpu_hotplug_driver_lock();
>  	rc = dlpar_offline_cpu(dn);
>  	if (rc) {
>  		of_node_put(dn);
> -		rc = -EINVAL;
> -		goto out;
> +		return -EINVAL;
>  	}
>  
>  	rc = dlpar_release_drc(*drc_index);
>  	if (rc) {
>  		of_node_put(dn);
> -		goto out;
> +		return rc;
>  	}
>  
>  	rc = dlpar_detach_node(dn);
>  	if (rc) {
>  		dlpar_acquire_drc(*drc_index);
> -		goto out;
> +		return rc;
>  	}
>  
>  	of_node_put(dn);
> -out:
> -	cpu_hotplug_driver_unlock();
> -	return rc ? rc : count;
> +
> +	return count;
>  }
>  
>  static int __init pseries_dlpar_init(void)
> diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
> index a3f35eb..649b010 100644
> --- a/arch/x86/kernel/topology.c
> +++ b/arch/x86/kernel/topology.c
> @@ -66,7 +66,6 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
>  		return -EINVAL;
>  
>  	lock_device_hotplug();
> -	cpu_hotplug_driver_lock();
>  
>  	switch (action) {
>  	case 0:
> @@ -91,7 +90,6 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
>  		ret = -EINVAL;
>  	}
>  
> -	cpu_hotplug_driver_unlock();
>  	unlock_device_hotplug();
>  
>  	return ret;
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index 4cc6928..b4ebd7b 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -45,8 +45,6 @@ static int __ref cpu_subsys_online(struct device *dev)
>  	int from_nid, to_nid;
>  	int ret;
>  
> -	cpu_hotplug_driver_lock();
> -
>  	from_nid = cpu_to_node(cpuid);
>  	ret = cpu_up(cpuid);
>  	/*
> @@ -57,18 +55,12 @@ static int __ref cpu_subsys_online(struct device *dev)
>  	if (from_nid != to_nid)
>  		change_cpu_under_node(cpu, from_nid, to_nid);
>  
> -	cpu_hotplug_driver_unlock();
>  	return ret;
>  }
>  
>  static int cpu_subsys_offline(struct device *dev)
>  {
> -	int ret;
> -
> -	cpu_hotplug_driver_lock();
> -	ret = cpu_down(dev->id);
> -	cpu_hotplug_driver_unlock();
> -	return ret;
> +	return cpu_down(dev->id);
>  }
>  
>  void unregister_cpu(struct cpu *cpu)
> diff --git a/include/linux/cpu.h b/include/linux/cpu.h
> index ab0eade..e847ef8 100644
> --- a/include/linux/cpu.h
> +++ b/include/linux/cpu.h
> @@ -182,19 +182,6 @@ extern void cpu_hotplug_enable(void);
>  void clear_tasks_mm_cpumask(int cpu);
>  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)
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
>
Toshi Kani - Aug. 19, 2013, 3:23 p.m.
On Mon, 2013-08-19 at 10:20 -0500, Nathan Fontenot wrote:
> On 08/17/2013 02:46 PM, Toshi Kani wrote:
> > cpu_hotplug_driver_lock() serializes CPU online/offline operations
> > when ARCH_CPU_PROBE_RELEASE is set.  This lock interface is no longer
> > necessary with the following reason:
> > 
> >  - lock_device_hotplug() now protects CPU online/offline operations,
> >    including the probe & release interfaces enabled by
> >    ARCH_CPU_PROBE_RELEASE.  The use of cpu_hotplug_driver_lock() is
> >    redundant.
> >  - cpu_hotplug_driver_lock() is only valid when ARCH_CPU_PROBE_RELEASE
> >    is defined, which is misleading and is only enabled on powerpc.
> > 
> > This patch removes the cpu_hotplug_driver_lock() interface.  As
> > a result, ARCH_CPU_PROBE_RELEASE only enables / disables the cpu
> > probe & release interface as intended.  There is no functional change
> > in this patch.
> > 
> > Signed-off-by: Toshi Kani <toshi.kani@hp.com>
> 
> Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>

Thanks Nathan!
-Toshi

Patch

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 38b0ba6..1667269 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -763,18 +763,6 @@  void __cpu_die(unsigned int cpu)
 		smp_ops->cpu_die(cpu);
 }
 
-static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);
-
-void cpu_hotplug_driver_lock()
-{
-	mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
-}
-
-void cpu_hotplug_driver_unlock()
-{
-	mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
-}
-
 void cpu_die(void)
 {
 	if (ppc_md.cpu_die)
diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index a1a7b9a..e39325d 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -387,18 +387,13 @@  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) {
-		rc = -EINVAL;
-		goto out;
-	}
+	if (rc)
+		return -EINVAL;
 
 	dn = dlpar_configure_connector(drc_index);
-	if (!dn) {
-		rc = -EINVAL;
-		goto out;
-	}
+	if (!dn)
+		return -EINVAL;
 
 	/* configure-connector reports cpus as living in the base
 	 * directory of the device tree.  CPUs actually live in the
@@ -407,8 +402,7 @@  static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 	cpu_name = kasprintf(GFP_KERNEL, "/cpus%s", dn->full_name);
 	if (!cpu_name) {
 		dlpar_free_cc_nodes(dn);
-		rc = -ENOMEM;
-		goto out;
+		return -ENOMEM;
 	}
 
 	kfree(dn->full_name);
@@ -417,22 +411,21 @@  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);
-		rc = -EINVAL;
-		goto out;
+		return -EINVAL;
 	}
 
 	rc = dlpar_attach_node(dn);
 	if (rc) {
 		dlpar_release_drc(drc_index);
 		dlpar_free_cc_nodes(dn);
-		goto out;
+		return rc;
 	}
 
 	rc = dlpar_online_cpu(dn);
-out:
-	cpu_hotplug_driver_unlock();
+	if (rc)
+		return rc;
 
-	return rc ? rc : count;
+	return count;
 }
 
 static int dlpar_offline_cpu(struct device_node *dn)
@@ -505,30 +498,27 @@  static ssize_t dlpar_cpu_release(const char *buf, size_t count)
 		return -EINVAL;
 	}
 
-	cpu_hotplug_driver_lock();
 	rc = dlpar_offline_cpu(dn);
 	if (rc) {
 		of_node_put(dn);
-		rc = -EINVAL;
-		goto out;
+		return -EINVAL;
 	}
 
 	rc = dlpar_release_drc(*drc_index);
 	if (rc) {
 		of_node_put(dn);
-		goto out;
+		return rc;
 	}
 
 	rc = dlpar_detach_node(dn);
 	if (rc) {
 		dlpar_acquire_drc(*drc_index);
-		goto out;
+		return rc;
 	}
 
 	of_node_put(dn);
-out:
-	cpu_hotplug_driver_unlock();
-	return rc ? rc : count;
+
+	return count;
 }
 
 static int __init pseries_dlpar_init(void)
diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
index a3f35eb..649b010 100644
--- a/arch/x86/kernel/topology.c
+++ b/arch/x86/kernel/topology.c
@@ -66,7 +66,6 @@  int __ref _debug_hotplug_cpu(int cpu, int action)
 		return -EINVAL;
 
 	lock_device_hotplug();
-	cpu_hotplug_driver_lock();
 
 	switch (action) {
 	case 0:
@@ -91,7 +90,6 @@  int __ref _debug_hotplug_cpu(int cpu, int action)
 		ret = -EINVAL;
 	}
 
-	cpu_hotplug_driver_unlock();
 	unlock_device_hotplug();
 
 	return ret;
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 4cc6928..b4ebd7b 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -45,8 +45,6 @@  static int __ref cpu_subsys_online(struct device *dev)
 	int from_nid, to_nid;
 	int ret;
 
-	cpu_hotplug_driver_lock();
-
 	from_nid = cpu_to_node(cpuid);
 	ret = cpu_up(cpuid);
 	/*
@@ -57,18 +55,12 @@  static int __ref cpu_subsys_online(struct device *dev)
 	if (from_nid != to_nid)
 		change_cpu_under_node(cpu, from_nid, to_nid);
 
-	cpu_hotplug_driver_unlock();
 	return ret;
 }
 
 static int cpu_subsys_offline(struct device *dev)
 {
-	int ret;
-
-	cpu_hotplug_driver_lock();
-	ret = cpu_down(dev->id);
-	cpu_hotplug_driver_unlock();
-	return ret;
+	return cpu_down(dev->id);
 }
 
 void unregister_cpu(struct cpu *cpu)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index ab0eade..e847ef8 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -182,19 +182,6 @@  extern void cpu_hotplug_enable(void);
 void clear_tasks_mm_cpumask(int cpu);
 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)