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Subject[tip: smp/core] cpu/hotplug: Hide cpu_up/down()
The following commit has been merged into the smp/core branch of tip:

Commit-ID: 33c3736ec88811b9b6f6ce2cc8967f6b97c3db5e
Gitweb: https://git.kernel.org/tip/33c3736ec88811b9b6f6ce2cc8967f6b97c3db5e
Author: Qais Yousef <qais.yousef@arm.com>
AuthorDate: Mon, 23 Mar 2020 13:51:10
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 25 Mar 2020 12:59:38 +01:00

cpu/hotplug: Hide cpu_up/down()

Use separate functions for the device core to bring a CPU up and down.

Users outside the device core must use add/remove_cpu() which will take
care of extra housekeeping work like keeping sysfs in sync.

Make cpu_up/down() static and replace the extra layer of indirection.

[ tglx: Removed the extra wrapper functions and adjusted function names ]

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200323135110.30522-18-qais.yousef@arm.com
---
drivers/base/cpu.c | 4 ++--
include/linux/cpu.h | 4 ++--
kernel/cpu.c | 42 ++++++++++++++++++++++++++++--------------
3 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 6265871..b93a8f8 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -55,7 +55,7 @@ static int cpu_subsys_online(struct device *dev)
if (from_nid == NUMA_NO_NODE)
return -ENODEV;

- ret = cpu_up(cpuid);
+ ret = cpu_device_up(dev);
/*
* When hot adding memory to memoryless node and enabling a cpu
* on the node, node number of the cpu may internally change.
@@ -69,7 +69,7 @@ static int cpu_subsys_online(struct device *dev)

static int cpu_subsys_offline(struct device *dev)
{
- return cpu_down(dev->id);
+ return cpu_device_down(dev);
}

void unregister_cpu(struct cpu *cpu)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 8b295f7..9ead281 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -88,8 +88,8 @@ extern ssize_t arch_cpu_release(const char *, size_t);

#ifdef CONFIG_SMP
extern bool cpuhp_tasks_frozen;
-int cpu_up(unsigned int cpu);
int add_cpu(unsigned int cpu);
+int cpu_device_up(struct device *dev);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);
@@ -120,8 +120,8 @@ extern void lockdep_assert_cpus_held(void);
extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
void clear_tasks_mm_cpumask(int cpu);
-int cpu_down(unsigned int cpu);
int remove_cpu(unsigned int cpu);
+int cpu_device_down(struct device *dev);
extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);

#else /* CONFIG_HOTPLUG_CPU */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 4783d81..3084849 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1041,7 +1041,7 @@ static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target)
return _cpu_down(cpu, 0, target);
}

-static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
+static int cpu_down(unsigned int cpu, enum cpuhp_state target)
{
int err;

@@ -1051,11 +1051,18 @@ static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
return err;
}

-int cpu_down(unsigned int cpu)
+/**
+ * cpu_device_down - Bring down a cpu device
+ * @dev: Pointer to the cpu device to offline
+ *
+ * This function is meant to be used by device core cpu subsystem only.
+ *
+ * Other subsystems should use remove_cpu() instead.
+ */
+int cpu_device_down(struct device *dev)
{
- return do_cpu_down(cpu, CPUHP_OFFLINE);
+ return cpu_down(dev->id, CPUHP_OFFLINE);
}
-EXPORT_SYMBOL(cpu_down);

int remove_cpu(unsigned int cpu)
{
@@ -1178,8 +1185,8 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
}

/*
- * The caller of do_cpu_up might have raced with another
- * caller. Ignore it for now.
+ * The caller of cpu_up() might have raced with another
+ * caller. Nothing to do.
*/
if (st->state >= target)
goto out;
@@ -1223,7 +1230,7 @@ out:
return ret;
}

-static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
+static int cpu_up(unsigned int cpu, enum cpuhp_state target)
{
int err = 0;

@@ -1257,11 +1264,18 @@ out:
return err;
}

-int cpu_up(unsigned int cpu)
+/**
+ * cpu_device_up - Bring up a cpu device
+ * @dev: Pointer to the cpu device to online
+ *
+ * This function is meant to be used by device core cpu subsystem only.
+ *
+ * Other subsystems should use add_cpu() instead.
+ */
+int cpu_device_up(struct device *dev)
{
- return do_cpu_up(cpu, CPUHP_ONLINE);
+ return cpu_up(dev->id, CPUHP_ONLINE);
}
-EXPORT_SYMBOL_GPL(cpu_up);

int add_cpu(unsigned int cpu)
{
@@ -1289,7 +1303,7 @@ int bringup_hibernate_cpu(unsigned int sleep_cpu)

if (!cpu_online(sleep_cpu)) {
pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");
- ret = cpu_up(sleep_cpu);
+ ret = cpu_up(sleep_cpu, CPUHP_ONLINE);
if (ret) {
pr_err("Failed to bring hibernate-CPU up!\n");
return ret;
@@ -1306,7 +1320,7 @@ void bringup_nonboot_cpus(unsigned int setup_max_cpus)
if (num_online_cpus() >= setup_max_cpus)
break;
if (!cpu_online(cpu))
- cpu_up(cpu);
+ cpu_up(cpu, CPUHP_ONLINE);
}
}

@@ -2129,9 +2143,9 @@ static ssize_t write_cpuhp_target(struct device *dev,
goto out;

if (st->state < target)
- ret = do_cpu_up(dev->id, target);
+ ret = cpu_up(dev->id, target);
else
- ret = do_cpu_down(dev->id, target);
+ ret = cpu_down(dev->id, target);
out:
unlock_device_hotplug();
return ret ? ret : count;
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