cpuset: introduce CS_ONLINE

Add CS_ONLINE which is set from css_online() and cleared from
css_offline().  This will enable using generic cgroup iterator while
allowing decoupling cpuset from cgroup internal locking.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1d7a611ff771cbd5be792e41ce05d90bfa2d60bf..e857887bd2469efc88f5b82b6f7221196da6c6f3 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -138,6 +138,7 @@ static inline bool task_has_mempolicy(struct task_struct *task)
 
 /* bits in struct cpuset flags field */
 typedef enum {
+       CS_ONLINE,
        CS_CPU_EXCLUSIVE,
        CS_MEM_EXCLUSIVE,
        CS_MEM_HARDWALL,
@@ -154,6 +155,11 @@ enum hotplug_event {
 };
 
 /* convenient tests for these bits */
+static inline bool is_cpuset_online(const struct cpuset *cs)
+{
+       return test_bit(CS_ONLINE, &cs->flags);
+}
+
 static inline int is_cpu_exclusive(const struct cpuset *cs)
 {
        return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
@@ -190,7 +196,8 @@ static inline int is_spread_slab(const struct cpuset *cs)
 }
 
 static struct cpuset top_cpuset = {
-       .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
+       .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
+                 (1 << CS_MEM_EXCLUSIVE)),
 };
 
 /*
@@ -1822,6 +1829,7 @@ static int cpuset_css_online(struct cgroup *cgrp)
        if (!parent)
                return 0;
 
+       set_bit(CS_ONLINE, &cs->flags);
        if (is_spread_page(parent))
                set_bit(CS_SPREAD_PAGE, &cs->flags);
        if (is_spread_slab(parent))
@@ -1871,6 +1879,7 @@ static void cpuset_css_offline(struct cgroup *cgrp)
                update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
 
        number_of_cpusets--;
+       clear_bit(CS_ONLINE, &cs->flags);
 
        cgroup_unlock();
 }