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Date: Sat, 17 Aug 2013 13:46:59 -0600
From: Toshi Kani <toshi.kani@...com>
To: mingo@...hat.com, hpa@...ux.intel.com, tglx@...utronix.de,
gregkh@...uxfoundation.org, benh@...nel.crashing.org
Cc: x86@...nel.org, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org, rjw@...k.pl, fenghua.yu@...el.com,
bp@...e.de, srivatsa.bhat@...ux.vnet.ibm.com,
isimatu.yasuaki@...fujitsu.com, Toshi Kani <toshi.kani@...com>
Subject: [PATCH 4/4] 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@...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)
--
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