hotplug, powerpc, x86: Remove cpu_hotplug_driver_lock()

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

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 8e59abc237d7f17c96effa20583206e75b2e4b7a..930cd8af35035441031e1abecbdde3472ab48808 100644 (file)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -844,18 +844,6 @@ 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 7cfdaae1721a925c1d7370515917e7d9af5cc553..a8fe5aa3d34fd545f87a31995153effd8a63521b 100644 (file)
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -404,46 +404,38 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
        unsigned long drc_index;
        int rc;
 
-       cpu_hotplug_driver_lock();
        rc = strict_strtoul(buf, 0, &drc_index);
-       if (rc) {
-               rc = -EINVAL;
-               goto out;
-       }
+       if (rc)
+               return -EINVAL;
 
        parent = of_find_node_by_path("/cpus");
-       if (!parent) {
-               rc = -ENODEV;
-               goto out;
-       }
+       if (!parent)
+               return -ENODEV;
 
        dn = dlpar_configure_connector(drc_index, parent);
-       if (!dn) {
-               rc = -EINVAL;
-               goto out;
-       }
+       if (!dn)
+               return -EINVAL;
 
        of_node_put(parent);
 
        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)
@@ -516,30 +508,27 @@ 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 a3f35ebb3b52a0d6eb9e393bdef56c83446a6efc..649b010da00ba5a0c191a4144f2458c08f0500ab 100644 (file)
--- 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 51f5d7fe2f0b9e8ccb6e039684e6114391aa1210..f48370dfc908e19a73a86cf817ad05128c0ed034 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -44,13 +44,11 @@ static int __ref cpu_subsys_online(struct device *dev)
        struct cpu *cpu = container_of(dev, struct cpu, dev);
        int cpuid = dev->id;
        int from_nid, to_nid;
-       int ret = -ENODEV;
-
-       cpu_hotplug_driver_lock();
+       int ret;
 
        from_nid = cpu_to_node(cpuid);
        if (from_nid == NUMA_NO_NODE)
-               goto out;
+               return -ENODEV;
 
        ret = cpu_up(cpuid);
        /*
@@ -61,19 +59,12 @@ static int __ref cpu_subsys_online(struct device *dev)
        if (from_nid != to_nid)
                change_cpu_under_node(cpu, from_nid, to_nid);
 
- out:
-       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 801ff9e73679a00d7f945d82253454a236319966..3434ef7de017de0d5a33e7dd5dbfb173678c58c0 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -185,19 +185,6 @@ 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 */
 
 static inline void cpu_hotplug_begin(void) {}