(2012/11/03 17:38), Tejun Heo wrote:
Introduce FREEZING_SELF and FREEZING_PARENT and make FREEZING OR of
the two flags. This is to prepare for full hierarchy support.
freezer_apply_date() is updated such that it can handle setting and
clearing of both flags. The two flags are also exposed to userland
via read-only files self_freezing and parent_freezing.
Other than the added cgroupfs files, this patch doesn't introduce any
behavior change.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
What is the purpose of FREEZING_SELG/PARENT, having 2 flags and
make it visible to users ?
Thanks,
-Kame
---
kernel/cgroup_freezer.c | 55 ++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 47 insertions(+), 8 deletions(-)
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index e76aa9f..b8ad93c 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -23,8 +23,12 @@
#include <linux/seq_file.h>
enum freezer_state_flags {
- CGROUP_FREEZING = (1 << 1), /* this freezer is freezing */
+ CGROUP_FREEZING_SELF = (1 << 1), /* this freezer is freezing */
+ CGROUP_FREEZING_PARENT = (1 << 2), /* the parent freezer is freezing */
CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */
+
+ /* mask for all FREEZING flags */
+ CGROUP_FREEZING = CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT,
};
struct freezer {
@@ -245,8 +249,13 @@ static void unfreeze_cgroup(struct freezer *freezer)
* freezer_apply_state - apply state change to a single cgroup_freezer
* @freezer: freezer to apply state change to
* @freeze: whether to freeze or unfreeze
+ * @state: CGROUP_FREEZING_* flag to set or clear
+ *
+ * Set or clear @state on @cgroup according to @freeze, and perform
+ * freezing or thawing as necessary.
*/
-static void freezer_apply_state(struct freezer *freezer, bool freeze)
+static void freezer_apply_state(struct freezer *freezer, bool freeze,
+ unsigned int state)
{
/* also synchronizes against task migration, see freezer_attach() */
lockdep_assert_held(&freezer->lock);
@@ -254,13 +263,19 @@ static void freezer_apply_state(struct freezer *freezer, bool freeze)
if (freeze) {
if (!(freezer->state & CGROUP_FREEZING))
atomic_inc(&system_freezing_cnt);
- freezer->state |= CGROUP_FREEZING;
+ freezer->state |= state;
freeze_cgroup(freezer);
} else {
- if (freezer->state & CGROUP_FREEZING)
- atomic_dec(&system_freezing_cnt);
- freezer->state &= ~(CGROUP_FREEZING | CGROUP_FROZEN);
- unfreeze_cgroup(freezer);
+ bool was_freezing = freezer->state & CGROUP_FREEZING;
+
+ freezer->state &= ~state;
+
+ if (!(freezer->state & CGROUP_FREEZING)) {
+ if (was_freezing)
+ atomic_dec(&system_freezing_cnt);
+ freezer->state &= ~CGROUP_FROZEN;
+ unfreeze_cgroup(freezer);
+ }
}
}
@@ -275,7 +290,7 @@ static void freezer_change_state(struct freezer *freezer, bool freeze)
{
/* update @freezer */
spin_lock_irq(&freezer->lock);
- freezer_apply_state(freezer, freeze);
+ freezer_apply_state(freezer, freeze, CGROUP_FREEZING_SELF);
spin_unlock_irq(&freezer->lock);
}
@@ -295,6 +310,20 @@ static int freezer_write(struct cgroup *cgroup, struct cftype *cft,
return 0;
}
+static u64 freezer_self_freezing_read(struct cgroup *cgroup, struct cftype *cft)
+{
+ struct freezer *freezer = cgroup_freezer(cgroup);
+
+ return (bool)(freezer->state & CGROUP_FREEZING_SELF);
+}
+
+static u64 freezer_parent_freezing_read(struct cgroup *cgroup, struct cftype *cft)
+{
+ struct freezer *freezer = cgroup_freezer(cgroup);
+
+ return (bool)(freezer->state & CGROUP_FREEZING_PARENT);
+}
+
static struct cftype files[] = {
{
.name = "state",
@@ -302,6 +331,16 @@ static struct cftype files[] = {
.read_seq_string = freezer_read,
.write_string = freezer_write,
},
+ {
+ .name = "self_freezing",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_u64 = freezer_self_freezing_read,
+ },
+ {
+ .name = "parent_freezing",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_u64 = freezer_parent_freezing_read,
+ },
{ } /* terminate */
};
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