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| author | Gautham R Shenoy <ego@in.ibm.com> | 2008-01-25 21:08:02 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-01-25 21:08:02 +0100 |
| commit | 86ef5c9a8edd78e6bf92879f32329d89b2d55b5a (patch) | |
| tree | 7bf46885326a6fdbb0c3596855408e9a5634dd3a /kernel/cpuset.c | |
| parent | d221938c049f4845da13c8593132595a6b9222a8 (diff) | |
| download | lwn-86ef5c9a8edd78e6bf92879f32329d89b2d55b5a.tar.gz lwn-86ef5c9a8edd78e6bf92879f32329d89b2d55b5a.zip | |
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/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 14 |
1 files changed, 7 insertions, 7 deletions
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. */ |