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authorGautham R Shenoy <ego@in.ibm.com>2008-01-25 21:08:02 +0100
committerIngo Molnar <mingo@elte.hu>2008-01-25 21:08:02 +0100
commit86ef5c9a8edd78e6bf92879f32329d89b2d55b5a (patch)
tree7bf46885326a6fdbb0c3596855408e9a5634dd3a /kernel
parentd221938c049f4845da13c8593132595a6b9222a8 (diff)
downloadlinux-86ef5c9a8edd78e6bf92879f32329d89b2d55b5a.tar.bz2
cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()
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. The new API guarantees protection against the cpu-hotplug operation, but it doesn't guarantee serialized access to any of the local data structures. Hence the changes needs to be reviewed. In case of pseries_add_processor/pseries_remove_processor, use cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the cpu_present_map there. Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cpu.c10
-rw-r--r--kernel/cpuset.c14
-rw-r--r--kernel/rcutorture.c6
-rw-r--r--kernel/sched.c4
-rw-r--r--kernel/stop_machine.c4
5 files changed, 19 insertions, 19 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 656dc3fcbbae..b0c4152995f8 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -48,7 +48,7 @@ void __init cpu_hotplug_init(void)
#ifdef CONFIG_HOTPLUG_CPU
-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 */
@@ -110,7 +110,7 @@ void cpu_maps_update_done(void)
* non zero and goes to sleep again.
*
* However, this is very difficult to achieve in practice since
- * lock_cpu_hotplug() not an api which is called all that often.
+ * get_online_cpus() not an api which is called all that often.
*
*/
static void cpu_hotplug_begin(void)
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 50f5dc463688..cfaf6419d817 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -537,10 +537,10 @@ static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
*
* 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:
@@ -691,9 +691,9 @@ 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))
@@ -1617,10 +1617,10 @@ static struct cgroup_subsys_state *cpuset_create(
*
* 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.
*/
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index c3e165c2318f..fd599829e72a 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -726,11 +726,11 @@ static void rcu_torture_shuffle_tasks(void)
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(void)
else
rcu_idle_cpu--;
- unlock_cpu_hotplug();
+ put_online_cpus();
}
/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
diff --git a/kernel/sched.c b/kernel/sched.c
index 86e55a9c2de6..672aa68bfeac 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7152,7 +7152,7 @@ static int load_balance_monitor(void *unused)
int i, cpu, balanced = 1;
/* Prevent cpus going down or coming up */
- lock_cpu_hotplug();
+ get_online_cpus();
/* lockout changes to doms_cur[] array */
lock_doms_cur();
/*
@@ -7186,7 +7186,7 @@ static int load_balance_monitor(void *unused)
rcu_read_unlock();
unlock_doms_cur();
- unlock_cpu_hotplug();
+ put_online_cpus();
if (!balanced)
timeout = sysctl_sched_min_bal_int_shares;
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 319821ef78af..51b5ee53571a 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -203,13 +203,13 @@ int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
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;
}