[RFC PATCH 2/4] Rename lock_cpu_hotplug to get_online_cpus

From: Gautham R Shenoy
Date: Tue Oct 16 2007 - 06:35:50 EST

Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights
the refcount semantics in these operations.

Signed-off-by: Gautham R Shenoy <ego@xxxxxxxxxx>
---
arch/i386/kernel/cpu/mtrr/main.c | 8 ++++----
arch/i386/kernel/microcode.c | 16 ++++++++--------
arch/mips/kernel/mips-mt-fpaff.c | 10 +++++-----
arch/powerpc/platforms/pseries/hotplug-cpu.c | 8 ++++----
arch/powerpc/platforms/pseries/rtasd.c | 8 ++++----
drivers/lguest/core.c | 8 ++++----
drivers/s390/char/sclp_config.c | 4 ++--
include/linux/cpu.h | 10 +++++-----
kernel/cpu.c | 8 ++++----
kernel/cpuset.c | 14 +++++++-------
kernel/rcutorture.c | 6 +++---
kernel/stop_machine.c | 4 ++--
net/core/flow.c | 4 ++--
13 files changed, 54 insertions(+), 54 deletions(-)

Index: linux-2.6.23/include/linux/cpu.h
===================================================================
--- linux-2.6.23.orig/include/linux/cpu.h
+++ linux-2.6.23/include/linux/cpu.h
@@ -98,8 +98,8 @@ static inline void cpuhotplug_mutex_unlo
}

extern void cpu_hotplug_init(void);
-extern void lock_cpu_hotplug(void);
-extern void unlock_cpu_hotplug(void);
+extern void get_online_cpus(void);
+extern void put_online_cpus(void);
#define hotcpu_notifier(fn, pri) { \
static struct notifier_block fn##_nb = \
{ .notifier_call = fn, .priority = pri }; \
@@ -117,9 +117,9 @@ static inline void cpuhotplug_mutex_lock
static inline void cpuhotplug_mutex_unlock(struct mutex *cpu_hp_mutex)
{ }

-#define cpu_hotplug_init() do { } while (0)
-#define lock_cpu_hotplug() do { } while (0)
-#define unlock_cpu_hotplug() do { } while (0)
+#define cpu_hotplug_init() do { } while (0)
+#define get_online_cpus() do { } while (0)
+#define put_online_cpus() do { } while (0)
#define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
/* These aren't inline functions due to a GCC bug. */
#define register_hotcpu_notifier(nb) ({ (void)(nb); 0; })
Index: linux-2.6.23/kernel/cpu.c
===================================================================
--- linux-2.6.23.orig/kernel/cpu.c
+++ linux-2.6.23/kernel/cpu.c
@@ -48,7 +48,7 @@ void __init cpu_hotplug_init(void)
init_completion(&cpu_hotplug.readers_done);
}

-void lock_cpu_hotplug(void)
+void get_online_cpus(void)
{
might_sleep();
if (cpu_hotplug.active_writer == current)
@@ -58,9 +58,9 @@ void lock_cpu_hotplug(void)
mutex_unlock(&cpu_hotplug.lock);

}
-EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
+EXPORT_SYMBOL_GPL(get_online_cpus);

-void unlock_cpu_hotplug(void)
+void put_online_cpus(void)
{
if (cpu_hotplug.active_writer == current)
return;
@@ -73,7 +73,7 @@ void unlock_cpu_hotplug(void)
mutex_unlock(&cpu_hotplug.lock);

}
-EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
+EXPORT_SYMBOL_GPL(put_online_cpus);

#endif /* CONFIG_HOTPLUG_CPU */

Index: linux-2.6.23/kernel/stop_machine.c
===================================================================
--- linux-2.6.23.orig/kernel/stop_machine.c
+++ linux-2.6.23/kernel/stop_machine.c
@@ -203,13 +203,13 @@ int stop_machine_run(int (*fn)(void *),
int ret;

/* No CPUs can come up or down during this. */
- lock_cpu_hotplug();
+ get_online_cpus();
p = __stop_machine_run(fn, data, cpu);
if (!IS_ERR(p))
ret = kthread_stop(p);
else
ret = PTR_ERR(p);
- unlock_cpu_hotplug();
+ put_online_cpus();

return ret;
}
Index: linux-2.6.23/arch/i386/kernel/cpu/mtrr/main.c
===================================================================
--- linux-2.6.23.orig/arch/i386/kernel/cpu/mtrr/main.c
+++ linux-2.6.23/arch/i386/kernel/cpu/mtrr/main.c
@@ -351,7 +351,7 @@ int mtrr_add_page(unsigned long base, un
replace = -1;

/* No CPU hotplug when we change MTRR entries */
- lock_cpu_hotplug();
+ get_online_cpus();
/* Search for existing MTRR */
mutex_lock(&mtrr_mutex);
for (i = 0; i < num_var_ranges; ++i) {
@@ -407,7 +407,7 @@ int mtrr_add_page(unsigned long base, un
error = i;
out:
mutex_unlock(&mtrr_mutex);
- unlock_cpu_hotplug();
+ put_online_cpus();
return error;
}

@@ -497,7 +497,7 @@ int mtrr_del_page(int reg, unsigned long

max = num_var_ranges;
/* No CPU hotplug when we change MTRR entries */
- lock_cpu_hotplug();
+ get_online_cpus();
mutex_lock(&mtrr_mutex);
if (reg < 0) {
/* Search for existing MTRR */
@@ -538,7 +538,7 @@ int mtrr_del_page(int reg, unsigned long
error = reg;
out:
mutex_unlock(&mtrr_mutex);
- unlock_cpu_hotplug();
+ put_online_cpus();
return error;
}
/**
Index: linux-2.6.23/arch/i386/kernel/microcode.c
===================================================================
--- linux-2.6.23.orig/arch/i386/kernel/microcode.c
+++ linux-2.6.23/arch/i386/kernel/microcode.c
@@ -436,7 +436,7 @@ static ssize_t microcode_write (struct f
return -EINVAL;
}

- lock_cpu_hotplug();
+ get_online_cpus();
mutex_lock(&microcode_mutex);

user_buffer = (void __user *) buf;
@@ -447,7 +447,7 @@ static ssize_t microcode_write (struct f
ret = (ssize_t)len;

mutex_unlock(&microcode_mutex);
- unlock_cpu_hotplug();
+ put_online_cpus();

return ret;
}
@@ -658,14 +658,14 @@ static ssize_t reload_store(struct sys_d

old = current->cpus_allowed;

- lock_cpu_hotplug();
+ get_online_cpus();
set_cpus_allowed(current, cpumask_of_cpu(cpu));

mutex_lock(&microcode_mutex);
if (uci->valid)
err = cpu_request_microcode(cpu);
mutex_unlock(&microcode_mutex);
- unlock_cpu_hotplug();
+ put_online_cpus();
set_cpus_allowed(current, old);
}
if (err)
@@ -817,9 +817,9 @@ static int __init microcode_init (void)
return PTR_ERR(microcode_pdev);
}

- lock_cpu_hotplug();
+ get_online_cpus();
error = sysdev_driver_register(&cpu_sysdev_class, &mc_sysdev_driver);
- unlock_cpu_hotplug();
+ put_online_cpus();
if (error) {
microcode_dev_exit();
platform_device_unregister(microcode_pdev);
@@ -839,9 +839,9 @@ static void __exit microcode_exit (void)

unregister_hotcpu_notifier(&mc_cpu_notifier);

- lock_cpu_hotplug();
+ get_online_cpus();
sysdev_driver_unregister(&cpu_sysdev_class, &mc_sysdev_driver);
- unlock_cpu_hotplug();
+ put_online_cpus();

platform_device_unregister(microcode_pdev);
}
Index: linux-2.6.23/arch/powerpc/platforms/pseries/hotplug-cpu.c
===================================================================
--- linux-2.6.23.orig/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ linux-2.6.23/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -151,7 +151,7 @@ static int pseries_add_processor(struct
for (i = 0; i < nthreads; i++)
cpu_set(i, tmp);

- lock_cpu_hotplug();
+ get_online_cpus();

BUG_ON(!cpus_subset(cpu_present_map, cpu_possible_map));

@@ -188,7 +188,7 @@ static int pseries_add_processor(struct
}
err = 0;
out_unlock:
- unlock_cpu_hotplug();
+ put_online_cpus();
return err;
}

@@ -209,7 +209,7 @@ static void pseries_remove_processor(str

nthreads = len / sizeof(u32);

- lock_cpu_hotplug();
+ get_online_cpus();
for (i = 0; i < nthreads; i++) {
for_each_present_cpu(cpu) {
if (get_hard_smp_processor_id(cpu) != intserv[i])
@@ -223,7 +223,7 @@ static void pseries_remove_processor(str
printk(KERN_WARNING "Could not find cpu to remove "
"with physical id 0x%x\n", intserv[i]);
}
- unlock_cpu_hotplug();
+ put_online_cpus();
}

static int pseries_smp_notifier(struct notifier_block *nb,
Index: linux-2.6.23/arch/powerpc/platforms/pseries/rtasd.c
===================================================================
--- linux-2.6.23.orig/arch/powerpc/platforms/pseries/rtasd.c
+++ linux-2.6.23/arch/powerpc/platforms/pseries/rtasd.c
@@ -382,7 +382,7 @@ static void do_event_scan_all_cpus(long
{
int cpu;

- lock_cpu_hotplug();
+ get_online_cpus();
cpu = first_cpu(cpu_online_map);
for (;;) {
set_cpus_allowed(current, cpumask_of_cpu(cpu));
@@ -390,15 +390,15 @@ static void do_event_scan_all_cpus(long
set_cpus_allowed(current, CPU_MASK_ALL);

/* Drop hotplug lock, and sleep for the specified delay */
- unlock_cpu_hotplug();
+ put_online_cpus();
msleep_interruptible(delay);
- lock_cpu_hotplug();
+ get_online_cpus();

cpu = next_cpu(cpu, cpu_online_map);
if (cpu == NR_CPUS)
break;
}
- unlock_cpu_hotplug();
+ put_online_cpus();
}

static int rtasd(void *unused)
Index: linux-2.6.23/drivers/s390/char/sclp_config.c
===================================================================
--- linux-2.6.23.orig/drivers/s390/char/sclp_config.c
+++ linux-2.6.23/drivers/s390/char/sclp_config.c
@@ -29,12 +29,12 @@ static void sclp_cpu_capability_notify(s
struct sys_device *sysdev;

printk(KERN_WARNING TAG "cpu capability changed.\n");
- lock_cpu_hotplug();
+ get_online_cpus();
for_each_online_cpu(cpu) {
sysdev = get_cpu_sysdev(cpu);
kobject_uevent(&sysdev->kobj, KOBJ_CHANGE);
}
- unlock_cpu_hotplug();
+ put_online_cpus();
}

static void sclp_conf_receiver_fn(struct evbuf_header *evbuf)
Index: linux-2.6.23/kernel/rcutorture.c
===================================================================
--- linux-2.6.23.orig/kernel/rcutorture.c
+++ linux-2.6.23/kernel/rcutorture.c
@@ -726,11 +726,11 @@ static void rcu_torture_shuffle_tasks(vo
cpumask_t tmp_mask = CPU_MASK_ALL;
int i;

- lock_cpu_hotplug();
+ get_online_cpus();

/* No point in shuffling if there is only one online CPU (ex: UP) */
if (num_online_cpus() == 1) {
- unlock_cpu_hotplug();
+ put_online_cpus();
return;
}

@@ -762,7 +762,7 @@ static void rcu_torture_shuffle_tasks(vo
else
rcu_idle_cpu--;

- unlock_cpu_hotplug();
+ put_online_cpus();
}

/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
Index: linux-2.6.23/net/core/flow.c
===================================================================
--- linux-2.6.23.orig/net/core/flow.c
+++ linux-2.6.23/net/core/flow.c
@@ -296,7 +296,7 @@ void flow_cache_flush(void)
static DEFINE_MUTEX(flow_flush_sem);

/* Don't want cpus going down or up during this. */
- lock_cpu_hotplug();
+ get_online_cpus();
mutex_lock(&flow_flush_sem);
atomic_set(&info.cpuleft, num_online_cpus());
init_completion(&info.completion);
@@ -308,7 +308,7 @@ void flow_cache_flush(void)

wait_for_completion(&info.completion);
mutex_unlock(&flow_flush_sem);
- unlock_cpu_hotplug();
+ put_online_cpus();
}

static void __devinit flow_cache_cpu_prepare(int cpu)
Index: linux-2.6.23/arch/mips/kernel/mips-mt-fpaff.c
===================================================================
--- linux-2.6.23.orig/arch/mips/kernel/mips-mt-fpaff.c
+++ linux-2.6.23/arch/mips/kernel/mips-mt-fpaff.c
@@ -58,13 +58,13 @@ asmlinkage long mipsmt_sys_sched_setaffi
if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
return -EFAULT;

- lock_cpu_hotplug();
+ get_online_cpus();
read_lock(&tasklist_lock);

p = find_process_by_pid(pid);
if (!p) {
read_unlock(&tasklist_lock);
- unlock_cpu_hotplug();
+ put_online_cpus();
return -ESRCH;
}

@@ -106,7 +106,7 @@ asmlinkage long mipsmt_sys_sched_setaffi

out_unlock:
put_task_struct(p);
- unlock_cpu_hotplug();
+ put_online_cpus();
return retval;
}

@@ -125,7 +125,7 @@ asmlinkage long mipsmt_sys_sched_getaffi
if (len < real_len)
return -EINVAL;

- lock_cpu_hotplug();
+ get_online_cpus();
read_lock(&tasklist_lock);

retval = -ESRCH;
@@ -140,7 +140,7 @@ asmlinkage long mipsmt_sys_sched_getaffi

out_unlock:
read_unlock(&tasklist_lock);
- unlock_cpu_hotplug();
+ put_online_cpus();
if (retval)
return retval;
if (copy_to_user(user_mask_ptr, &mask, real_len))
Index: linux-2.6.23/drivers/lguest/core.c
===================================================================
--- linux-2.6.23.orig/drivers/lguest/core.c
+++ linux-2.6.23/drivers/lguest/core.c
@@ -735,7 +735,7 @@ static int __init init(void)

/* We don't need the complexity of CPUs coming and going while we're
* doing this. */
- lock_cpu_hotplug();
+ get_online_cpus();
if (cpu_has_pge) { /* We have a broader idea of "global". */
/* Remember that this was originally set (for cleanup). */
cpu_had_pge = 1;
@@ -745,7 +745,7 @@ static int __init init(void)
/* Turn off the feature in the global feature set. */
clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
}
- unlock_cpu_hotplug();
+ put_online_cpus();

/* All good! */
return 0;
@@ -759,13 +759,13 @@ static void __exit fini(void)
unmap_switcher();

/* If we had PGE before we started, turn it back on now. */
- lock_cpu_hotplug();
+ get_online_cpus();
if (cpu_had_pge) {
set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
/* adjust_pge's argument "1" means set PGE. */
on_each_cpu(adjust_pge, (void *)1, 0, 1);
}
- unlock_cpu_hotplug();
+ put_online_cpus();
}

/* The Host side of lguest can be a module. This is a nice way for people to
Index: linux-2.6.23/kernel/cpuset.c
===================================================================
--- linux-2.6.23.orig/kernel/cpuset.c
+++ linux-2.6.23/kernel/cpuset.c
@@ -536,10 +536,10 @@ static int cpusets_overlap(struct cpuset
*
* Call with cgroup_mutex held. May take callback_mutex during
* call due to the kfifo_alloc() and kmalloc() calls. May nest
- * a call to the lock_cpu_hotplug()/unlock_cpu_hotplug() pair.
+ * a call to the get_online_cpus()/put_online_cpus() pair.
* Must not be called holding callback_mutex, because we must not
- * call lock_cpu_hotplug() while holding callback_mutex. Elsewhere
- * the kernel nests callback_mutex inside lock_cpu_hotplug() calls.
+ * call get_online_cpus() while holding callback_mutex. Elsewhere
+ * the kernel nests callback_mutex inside get_online_cpus() calls.
* So the reverse nesting would risk an ABBA deadlock.
*
* The three key local variables below are:
@@ -673,9 +673,9 @@ restart:

rebuild:
/* Have scheduler rebuild sched domains */
- lock_cpu_hotplug();
+ get_online_cpus();
partition_sched_domains(ndoms, doms);
- unlock_cpu_hotplug();
+ put_online_cpus();

done:
if (q && !IS_ERR(q))
@@ -1503,10 +1503,10 @@ static struct cgroup_subsys_state *cpuse
*
* If the cpuset being removed has its flag 'sched_load_balance'
* enabled, then simulate turning sched_load_balance off, which
- * will call rebuild_sched_domains(). The lock_cpu_hotplug()
+ * will call rebuild_sched_domains(). The get_online_cpus()
* call in rebuild_sched_domains() must not be made while holding
* callback_mutex. Elsewhere the kernel nests callback_mutex inside
- * lock_cpu_hotplug() calls. So the reverse nesting would risk an
+ * get_online_cpus() calls. So the reverse nesting would risk an
* ABBA deadlock.
*/

--
Gautham R Shenoy
Linux Technology Center
IBM India.
"Freedom comes with a price tag of responsibility, which is still a bargain,
because Freedom is priceless!"
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