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authorLai Jiangshan <laijs@cn.fujitsu.com>2009-01-07 18:08:39 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-08 08:31:11 -0800
commit13337714f3b0307dc7f75ef5d83ecf0db2abbd65 (patch)
treef76dd8961b9287b25e2ea24d2d34fecc52d2c8a0 /kernel/cpuset.c
parente7c5ec9193d32b9559a3bb8893ceedbda85201ff (diff)
downloadlinux-2.6.34-ux500-13337714f3b0307dc7f75ef5d83ecf0db2abbd65.tar.gz
cpuset: rcu_read_lock() to protect task_cs()
task_cs() calls task_subsys_state(). We must use rcu_read_lock() to protect cgroup_subsys_state(). It's correct that top_cpuset is never freed, but cgroup_subsys_state() accesses css_set, this css_set maybe freed when task_cs() called. We use use rcu_read_lock() to protect it. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c11
1 files changed, 3 insertions, 8 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 345ace5117d..a841b5c01ef 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -375,14 +375,9 @@ void cpuset_update_task_memory_state(void)
struct task_struct *tsk = current;
struct cpuset *cs;
- if (task_cs(tsk) == &top_cpuset) {
- /* Don't need rcu for top_cpuset. It's never freed. */
- my_cpusets_mem_gen = top_cpuset.mems_generation;
- } else {
- rcu_read_lock();
- my_cpusets_mem_gen = task_cs(tsk)->mems_generation;
- rcu_read_unlock();
- }
+ rcu_read_lock();
+ my_cpusets_mem_gen = task_cs(tsk)->mems_generation;
+ rcu_read_unlock();
if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
mutex_lock(&callback_mutex);