[PATCH V2] suspend: enable freeze timeout configuration through sys

fli24
2013-01-30T06:25:13Z

At present, the timeout value for freezing tasks is fixed as 20s,
which is too long for handheld device usage, especially for mobile
phone.

In order to improve user experience, we enable freeze timeout
configuration through sys, so that we can tune the value easily
for concrete usage, such as smaller value for handheld device such
as mobile phone.

Signed-off-by: Liu Chuansheng <chuansheng.liu@intel.com>
Signed-off-by: Li Fei <fei.li@intel.com>
---
Documentation/power/freezing-of-tasks.txt | 5 +++++
include/linux/freezer.h | 5 +++++
kernel/power/main.c | 27 +++++++++++++++++++++++++++
kernel/power/process.c | 4 ++--
4 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/Documentation/power/freezing-of-tasks.txt b/Documentation/power/freezing-of-tasks.txt
index 6ec291e..85894d8 100644
--- a/Documentation/power/freezing-of-tasks.txt
+++ b/Documentation/power/freezing-of-tasks.txt
@@ -223,3 +223,8 @@ since they ask the freezer to skip freezing this task, since it is anyway
only after the entire suspend/hibernation sequence is complete.
So, to summarize, use [un]lock_system_sleep() instead of directly using
mutex_[un]lock(&pm_mutex). That would prevent freezing failures.
+
+V. Miscellaneous
+/sys/power/pm_freeze_timeout controls how long it will cost at most to freeze
+all user space processes or all freezable kernel threads, in unit of millisecond.
+The default value is 20000, with range of unsigned integer.
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index e4238ce..5a24a33 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -13,6 +13,11 @@ extern bool pm_freezing; /* PM freezing in effect */
extern bool pm_nosig_freezing; /* PM nosig freezing in effect */

/*
+ * Timeout for stopping processes
+ */
+extern unsigned int sys_freeze_process_timeout_msecs;
+
+/*
* Check if a process has been frozen
*/
static inline bool frozen(struct task_struct *p)
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 1c16f91..453ead1 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -553,6 +553,30 @@ power_attr(pm_trace_dev_match);

#endif /* CONFIG_PM_TRACE */

+#ifdef CONFIG_FREEZER
+static ssize_t pm_freeze_timeout_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%u\n", sys_freeze_process_timeout_msecs);
+}
+
+static ssize_t pm_freeze_timeout_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t n)
+{
+ unsigned long val;
+
+ if (kstrtoul(buf, 10, &val))
+ return -EINVAL;
+
+ sys_freeze_process_timeout_msecs = val;
+ return n;
+}
+
+power_attr(pm_freeze_timeout);
+
+#endif /* CONFIG_FREEZER*/
+
static struct attribute * g[] = {
&state_attr.attr,
#ifdef CONFIG_PM_TRACE
@@ -576,6 +600,9 @@ static struct attribute * g[] = {
&pm_print_times_attr.attr,
#endif
#endif
+#ifdef CONFIG_FREEZER
+ &pm_freeze_timeout_attr.attr,
+#endif
NULL,
};

diff --git a/kernel/power/process.c b/kernel/power/process.c
index d5a258b..ba45a26 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -21,7 +21,7 @@
/*
* Timeout for stopping processes
*/
-#define TIMEOUT (20 * HZ)
+unsigned int __read_mostly sys_freeze_process_timeout_msecs = 20000;

static int try_to_freeze_tasks(bool user_only)
{
@@ -36,7 +36,7 @@ static int try_to_freeze_tasks(bool user_only)

do_gettimeofday(&start);

- end_time = jiffies + TIMEOUT;
+ end_time = jiffies + msecs_to_jiffies(sys_freeze_process_timeout_msecs);

if (!user_only)
freeze_workqueues_begin();
--
1.7.4.1