[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/kernel/cgroup_freezer.c b/ap/os/linux/linux-3.4.x/kernel/cgroup_freezer.c
new file mode 100644
index 0000000..a902e2a
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/kernel/cgroup_freezer.c
@@ -0,0 +1,376 @@
+/*
+ * cgroup_freezer.c - control group freezer subsystem
+ *
+ * Copyright IBM Corporation, 2007
+ *
+ * Author : Cedric Le Goater <clg@fr.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/cgroup.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/freezer.h>
+#include <linux/seq_file.h>
+
+enum freezer_state {
+ CGROUP_THAWED = 0,
+ CGROUP_FREEZING,
+ CGROUP_FROZEN,
+};
+
+struct freezer {
+ struct cgroup_subsys_state css;
+ enum freezer_state state;
+ spinlock_t lock; /* protects _writes_ to state */
+};
+
+static inline struct freezer *cgroup_freezer(
+ struct cgroup *cgroup)
+{
+ return container_of(
+ cgroup_subsys_state(cgroup, freezer_subsys_id),
+ struct freezer, css);
+}
+
+static inline struct freezer *task_freezer(struct task_struct *task)
+{
+ return container_of(task_subsys_state(task, freezer_subsys_id),
+ struct freezer, css);
+}
+
+bool cgroup_freezing(struct task_struct *task)
+{
+ enum freezer_state state;
+ bool ret;
+
+ rcu_read_lock();
+ state = task_freezer(task)->state;
+ ret = state == CGROUP_FREEZING || state == CGROUP_FROZEN;
+ rcu_read_unlock();
+
+ return ret;
+}
+
+/*
+ * cgroups_write_string() limits the size of freezer state strings to
+ * CGROUP_LOCAL_BUFFER_SIZE
+ */
+static const char *freezer_state_strs[] = {
+ "THAWED",
+ "FREEZING",
+ "FROZEN",
+};
+
+/*
+ * State diagram
+ * Transitions are caused by userspace writes to the freezer.state file.
+ * The values in parenthesis are state labels. The rest are edge labels.
+ *
+ * (THAWED) --FROZEN--> (FREEZING) --FROZEN--> (FROZEN)
+ * ^ ^ | |
+ * | \_______THAWED_______/ |
+ * \__________________________THAWED____________/
+ */
+
+struct cgroup_subsys freezer_subsys;
+
+/* Locks taken and their ordering
+ * ------------------------------
+ * cgroup_mutex (AKA cgroup_lock)
+ * freezer->lock
+ * css_set_lock
+ * task->alloc_lock (AKA task_lock)
+ * task->sighand->siglock
+ *
+ * cgroup code forces css_set_lock to be taken before task->alloc_lock
+ *
+ * freezer_create(), freezer_destroy():
+ * cgroup_mutex [ by cgroup core ]
+ *
+ * freezer_can_attach():
+ * cgroup_mutex (held by caller of can_attach)
+ *
+ * freezer_fork() (preserving fork() performance means can't take cgroup_mutex):
+ * freezer->lock
+ * sighand->siglock (if the cgroup is freezing)
+ *
+ * freezer_read():
+ * cgroup_mutex
+ * freezer->lock
+ * write_lock css_set_lock (cgroup iterator start)
+ * task->alloc_lock
+ * read_lock css_set_lock (cgroup iterator start)
+ *
+ * freezer_write() (freeze):
+ * cgroup_mutex
+ * freezer->lock
+ * write_lock css_set_lock (cgroup iterator start)
+ * task->alloc_lock
+ * read_lock css_set_lock (cgroup iterator start)
+ * sighand->siglock (fake signal delivery inside freeze_task())
+ *
+ * freezer_write() (unfreeze):
+ * cgroup_mutex
+ * freezer->lock
+ * write_lock css_set_lock (cgroup iterator start)
+ * task->alloc_lock
+ * read_lock css_set_lock (cgroup iterator start)
+ * task->alloc_lock (inside __thaw_task(), prevents race with refrigerator())
+ * sighand->siglock
+ */
+static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup)
+{
+ struct freezer *freezer;
+
+ freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL);
+ if (!freezer)
+ return ERR_PTR(-ENOMEM);
+
+ spin_lock_init(&freezer->lock);
+ freezer->state = CGROUP_THAWED;
+ return &freezer->css;
+}
+
+static void freezer_destroy(struct cgroup *cgroup)
+{
+ struct freezer *freezer = cgroup_freezer(cgroup);
+
+ if (freezer->state != CGROUP_THAWED)
+ atomic_dec(&system_freezing_cnt);
+ kfree(freezer);
+}
+
+/* task is frozen or will freeze immediately when next it gets woken */
+static bool is_task_frozen_enough(struct task_struct *task)
+{
+ return frozen(task) ||
+ (task_is_stopped_or_traced(task) && freezing(task));
+}
+
+/*
+ * The call to cgroup_lock() in the freezer.state write method prevents
+ * a write to that file racing against an attach, and hence the
+ * can_attach() result will remain valid until the attach completes.
+ */
+static int freezer_can_attach(struct cgroup *new_cgroup,
+ struct cgroup_taskset *tset)
+{
+ struct freezer *freezer;
+ struct task_struct *task;
+
+ /*
+ * Anything frozen can't move or be moved to/from.
+ */
+ cgroup_taskset_for_each(task, new_cgroup, tset)
+ if (cgroup_freezing(task))
+ return -EBUSY;
+
+ freezer = cgroup_freezer(new_cgroup);
+ if (freezer->state != CGROUP_THAWED)
+ return -EBUSY;
+
+ return 0;
+}
+
+static void freezer_fork(struct task_struct *task)
+{
+ struct freezer *freezer;
+
+ rcu_read_lock();
+ freezer = task_freezer(task);
+
+ /*
+ * The root cgroup is non-freezable, so we can skip the
+ * following check.
+ */
+ if (!freezer->css.cgroup->parent)
+ goto out;
+
+ spin_lock_irq(&freezer->lock);
+ BUG_ON(freezer->state == CGROUP_FROZEN);
+
+ /* Locking avoids race with FREEZING -> THAWED transitions. */
+ if (freezer->state == CGROUP_FREEZING)
+ freeze_task(task);
+
+ spin_unlock_irq(&freezer->lock);
+out:
+ rcu_read_unlock();
+}
+
+/*
+ * caller must hold freezer->lock
+ */
+static void update_if_frozen(struct cgroup *cgroup,
+ struct freezer *freezer)
+{
+ struct cgroup_iter it;
+ struct task_struct *task;
+ unsigned int nfrozen = 0, ntotal = 0;
+ enum freezer_state old_state = freezer->state;
+
+ cgroup_iter_start(cgroup, &it);
+ while ((task = cgroup_iter_next(cgroup, &it))) {
+ ntotal++;
+ if (freezing(task) && is_task_frozen_enough(task))
+ nfrozen++;
+ }
+
+ if (old_state == CGROUP_THAWED) {
+ BUG_ON(nfrozen > 0);
+ } else if (old_state == CGROUP_FREEZING) {
+ if (nfrozen == ntotal)
+ freezer->state = CGROUP_FROZEN;
+ } else { /* old_state == CGROUP_FROZEN */
+ BUG_ON(nfrozen != ntotal);
+ }
+
+ cgroup_iter_end(cgroup, &it);
+}
+
+static int freezer_read(struct cgroup *cgroup, struct cftype *cft,
+ struct seq_file *m)
+{
+ struct freezer *freezer;
+ enum freezer_state state;
+
+ if (!cgroup_lock_live_group(cgroup))
+ return -ENODEV;
+
+ freezer = cgroup_freezer(cgroup);
+ spin_lock_irq(&freezer->lock);
+ state = freezer->state;
+ if (state == CGROUP_FREEZING) {
+ /* We change from FREEZING to FROZEN lazily if the cgroup was
+ * only partially frozen when we exitted write. */
+ update_if_frozen(cgroup, freezer);
+ state = freezer->state;
+ }
+ spin_unlock_irq(&freezer->lock);
+ cgroup_unlock();
+
+ seq_puts(m, freezer_state_strs[state]);
+ seq_putc(m, '\n');
+ return 0;
+}
+
+static int try_to_freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
+{
+ struct cgroup_iter it;
+ struct task_struct *task;
+ unsigned int num_cant_freeze_now = 0;
+
+ cgroup_iter_start(cgroup, &it);
+ while ((task = cgroup_iter_next(cgroup, &it))) {
+ if (!freeze_task(task))
+ continue;
+ if (is_task_frozen_enough(task))
+ continue;
+ if (!freezing(task) && !freezer_should_skip(task))
+ num_cant_freeze_now++;
+ }
+ cgroup_iter_end(cgroup, &it);
+
+ return num_cant_freeze_now ? -EBUSY : 0;
+}
+
+static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
+{
+ struct cgroup_iter it;
+ struct task_struct *task;
+
+ cgroup_iter_start(cgroup, &it);
+ while ((task = cgroup_iter_next(cgroup, &it)))
+ __thaw_task(task);
+ cgroup_iter_end(cgroup, &it);
+}
+
+static int freezer_change_state(struct cgroup *cgroup,
+ enum freezer_state goal_state)
+{
+ struct freezer *freezer;
+ int retval = 0;
+
+ freezer = cgroup_freezer(cgroup);
+
+ spin_lock_irq(&freezer->lock);
+
+ update_if_frozen(cgroup, freezer);
+
+ switch (goal_state) {
+ case CGROUP_THAWED:
+ if (freezer->state != CGROUP_THAWED)
+ atomic_dec(&system_freezing_cnt);
+ freezer->state = CGROUP_THAWED;
+ unfreeze_cgroup(cgroup, freezer);
+ break;
+ case CGROUP_FROZEN:
+ if (freezer->state == CGROUP_THAWED)
+ atomic_inc(&system_freezing_cnt);
+ freezer->state = CGROUP_FREEZING;
+ retval = try_to_freeze_cgroup(cgroup, freezer);
+ break;
+ default:
+ BUG();
+ }
+
+ spin_unlock_irq(&freezer->lock);
+
+ return retval;
+}
+
+static int freezer_write(struct cgroup *cgroup,
+ struct cftype *cft,
+ const char *buffer)
+{
+ int retval;
+ enum freezer_state goal_state;
+
+ if (strcmp(buffer, freezer_state_strs[CGROUP_THAWED]) == 0)
+ goal_state = CGROUP_THAWED;
+ else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
+ goal_state = CGROUP_FROZEN;
+ else
+ return -EINVAL;
+
+ if (!cgroup_lock_live_group(cgroup))
+ return -ENODEV;
+ retval = freezer_change_state(cgroup, goal_state);
+ cgroup_unlock();
+ return retval;
+}
+
+static struct cftype files[] = {
+ {
+ .name = "state",
+ .read_seq_string = freezer_read,
+ .write_string = freezer_write,
+ },
+};
+
+static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
+{
+ if (!cgroup->parent)
+ return 0;
+ return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
+}
+
+struct cgroup_subsys freezer_subsys = {
+ .name = "freezer",
+ .create = freezer_create,
+ .destroy = freezer_destroy,
+ .populate = freezer_populate,
+ .subsys_id = freezer_subsys_id,
+ .can_attach = freezer_can_attach,
+ .fork = freezer_fork,
+};