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Subject[PATCH] PM / Sleep: Use workqueue for user space wakeup sources garbage collector
Date
From: "cleaeye.kim" <cleaneye.kim@lge.com>

The synchronous synchronize_rcu in wakeup_source_remove makes user process
which writes to /sys/kernel/wake_unlock blocked sometimes.

For example, when android eventhub tries to release wakelock,
this blocking process can occur, and eventhub can't get input event
for a while.

Using workqueue instead of direct function call at pm_wake_unlock
can prevent this unnecessary delay of an user space process.

Signed-off-by: cleaeye.kim <cleaneye.kim@lge.com>
---
kernel/power/wakelock.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/power/wakelock.c b/kernel/power/wakelock.c
index 019069c..ea10baa 100644
--- a/kernel/power/wakelock.c
+++ b/kernel/power/wakelock.c
@@ -17,6 +17,7 @@
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
+#include <linux/workqueue.h>

#include "power.h"

@@ -96,7 +97,7 @@ static inline void wakelocks_lru_most_recent(struct wakelock *wl)
list_move(&wl->lru, &wakelocks_lru_list);
}

-static void wakelocks_gc(void)
+static void wakelocks_gc(struct work_struct *work)
{
struct wakelock *wl, *aux;
ktime_t now;
@@ -105,6 +106,7 @@ static void wakelocks_gc(void)
return;

now = ktime_get();
+ mutex_lock(&wakelocks_lock);
list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
u64 idle_time_ns;
bool active;
@@ -126,12 +128,15 @@ static void wakelocks_gc(void)
decrement_wakelocks_number();
}
}
+ mutex_unlock(&wakelocks_lock);
wakelocks_gc_count = 0;
}
+
+static DECLARE_WORK(wakelock_work, wakelocks_gc);
#else /* !CONFIG_PM_WAKELOCKS_GC */
static inline void wakelocks_lru_add(struct wakelock *wl) {}
static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
-static inline void wakelocks_gc(void) {}
+static void wakelocks_gc(struct worksturct) {}
#endif /* !CONFIG_PM_WAKELOCKS_GC */

static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
@@ -260,7 +265,7 @@ int pm_wake_unlock(const char *buf)
__pm_relax(&wl->ws);

wakelocks_lru_most_recent(wl);
- wakelocks_gc();
+ schedule_work(&wakelock_work);

out:
mutex_unlock(&wakelocks_lock);
--
1.7.9.5


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