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Subject[PATCH v2 2/4] hotplug, x86: Add hotplug lock to missing places
Date
lock_device_hotplug[_sysfs]() serializes CPU & Memory online/offline
and hotplug operations. However, this lock is not held in the debug
interfaces below that initiate CPU online/offline operations.

- _debug_hotplug_cpu(), cpu0 hotplug test interface enabled by
CONFIG_DEBUG_HOTPLUG_CPU0.
- cpu_probe_store() and cpu_release_store(), cpu hotplug test interface
enabled by CONFIG_ARCH_CPU_PROBE_RELEASE.

This patch changes the above interfaces to hold lock_device_hotplug().

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
arch/x86/kernel/topology.c | 2 ++
drivers/base/cpu.c | 24 ++++++++++++++++++++++--
2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
index 5823bbd..a3f35eb 100644
--- a/arch/x86/kernel/topology.c
+++ b/arch/x86/kernel/topology.c
@@ -65,6 +65,7 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
if (!cpu_is_hotpluggable(cpu))
return -EINVAL;

+ lock_device_hotplug();
cpu_hotplug_driver_lock();

switch (action) {
@@ -91,6 +92,7 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
}

cpu_hotplug_driver_unlock();
+ unlock_device_hotplug();

return ret;
}
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 4cf0717..dc78e45 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -89,7 +89,17 @@ static ssize_t cpu_probe_store(struct device *dev,
const char *buf,
size_t count)
{
- return arch_cpu_probe(buf, count);
+ ssize_t cnt;
+ int ret;
+
+ ret = lock_device_hotplug_sysfs();
+ if (ret)
+ return ret;
+
+ cnt = arch_cpu_probe(buf, count);
+
+ unlock_device_hotplug();
+ return cnt;
}

static ssize_t cpu_release_store(struct device *dev,
@@ -97,7 +107,17 @@ static ssize_t cpu_release_store(struct device *dev,
const char *buf,
size_t count)
{
- return arch_cpu_release(buf, count);
+ ssize_t cnt;
+ int ret;
+
+ ret = lock_device_hotplug_sysfs();
+ if (ret)
+ return ret;
+
+ cnt = arch_cpu_release(buf, count);
+
+ unlock_device_hotplug();
+ return cnt;
}

static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);

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