[PATCH 8/9] PM: suspend_block: Add timeout support.

["Arve Hjønnevåg" <arve@android.com>]

Add suspend_block_timeout to block suspend for a limited time.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 Documentation/power/suspend-blockers.txt |   10 ++
 include/linux/suspend_blocker.h          |    7 +-
 kernel/power/suspend_blocker.c           |  235 +++++++++++++++++++++++++----
 3 files changed, 218 insertions(+), 34 deletions(-)

diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txt
index d81e20e..fd9f932 100644
--- a/Documentation/power/suspend-blockers.txt
+++ b/Documentation/power/suspend-blockers.txt
@@ -93,6 +93,16 @@ if (list_empty(&state->pending_work))
 else
 	suspend_block(&state->suspend_blocker);
 
+A driver can also call suspend_block_timeout to release the suspend_blocker
+after a delay:
+	suspend_block_timeout(&state->suspend_blocker, HZ);
+
+This works whether the suspend_blocker is already active or not. It is useful if
+the driver woke up other parts of the system that do not use suspend_blockers
+but still need to run. Avoid this when possible, since it will waste power
+if the timeout is long or may fail to finish needed work if the timeout is
+short. Calling suspend_block or suspend_unblock will cancel the timeout.
+
 User-space API
 ==============
 
diff --git a/include/linux/suspend_blocker.h b/include/linux/suspend_blocker.h
index 3bb8a6a..e3ae136 100755
--- a/include/linux/suspend_blocker.h
+++ b/include/linux/suspend_blocker.h
@@ -22,8 +22,9 @@
 /**
  * struct suspend_blocker - the basic suspend_blocker structure
  * @link:	List entry for active or inactive list.
- * @flags:	Tracks initialized, active and stats state.
+ * @flags:	Tracks initialized, active, stats and autoexpire state.
  * @name:	Name used for debugging.
+ * @expires:	Time, in jiffies, to unblock suspend.
  * @count:	Number of times this blocker has been deacivated
  * @wakeup_count: Number of times this blocker was the first to block suspend
  *		after resume.
@@ -44,9 +45,11 @@ struct suspend_blocker {
 	struct list_head    link;
 	int                 flags;
 	const char         *name;
+	unsigned long       expires;
 #ifdef CONFIG_SUSPEND_BLOCKER_STATS
 	struct {
 		int             count;
+		int             expire_count;
 		int             wakeup_count;
 		ktime_t         total_time;
 		ktime_t         prevent_suspend_time;
@@ -62,6 +65,7 @@ struct suspend_blocker {
 void suspend_blocker_init(struct suspend_blocker *blocker, const char *name);
 void suspend_blocker_destroy(struct suspend_blocker *blocker);
 void suspend_block(struct suspend_blocker *blocker);
+void suspend_block_timeout(struct suspend_blocker *blocker, long timeout);
 void suspend_unblock(struct suspend_blocker *blocker);
 bool suspend_blocker_is_active(struct suspend_blocker *blocker);
 bool suspend_is_blocked(void);
@@ -72,6 +76,7 @@ static inline void suspend_blocker_init(struct suspend_blocker *blocker,
 					const char *name) {}
 static inline void suspend_blocker_destroy(struct suspend_blocker *blocker) {}
 static inline void suspend_block(struct suspend_blocker *blocker) {}
+static inline void suspend_block_timeout(struct suspend_blocker *bl, long t) {}
 static inline void suspend_unblock(struct suspend_blocker *blocker) {}
 static inline bool suspend_blocker_is_active(struct suspend_blocker *bl)
 								{ return 0; }
diff --git a/kernel/power/suspend_blocker.c b/kernel/power/suspend_blocker.c
index ab4d8d5..fbe4903 100644
--- a/kernel/power/suspend_blocker.c
+++ b/kernel/power/suspend_blocker.c
@@ -27,13 +27,15 @@ enum {
 	DEBUG_USER_STATE = 1U << 2,
 	DEBUG_SUSPEND = 1U << 3,
 	DEBUG_SUSPEND_BLOCKER = 1U << 4,
+	DEBUG_EXPIRE = 1U << 5,
 };
 static int debug_mask = DEBUG_EXIT_SUSPEND | DEBUG_WAKEUP | DEBUG_USER_STATE;
 module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
 
 #define SB_INITIALIZED            (1U << 8)
 #define SB_ACTIVE                 (1U << 9)
-#define SB_PREVENTING_SUSPEND     (1U << 10)
+#define SB_AUTO_EXPIRE            (1U << 10)
+#define SB_PREVENTING_SUSPEND     (1U << 11)
 
 static DEFINE_SPINLOCK(list_lock);
 static DEFINE_SPINLOCK(state_lock);
@@ -64,20 +66,53 @@ static struct suspend_blocker deleted_suspend_blockers;
 static ktime_t last_sleep_time_update;
 static bool wait_for_wakeup;
 
+static bool stats_get_expired_time(struct suspend_blocker *blocker,
+				   ktime_t *expire_time)
+{
+	struct timespec ts;
+	struct timespec kt;
+	struct timespec tomono;
+	struct timespec delta;
+	unsigned long seq;
+	long timeout;
+
+	if (!(blocker->flags & SB_AUTO_EXPIRE))
+		return false;
+	do {
+		seq = read_seqbegin(&xtime_lock);
+		timeout = blocker->expires - jiffies;
+		if (timeout > 0)
+			return false;
+		kt = current_kernel_time();
+		tomono = wall_to_monotonic;
+	} while (read_seqretry(&xtime_lock, seq));
+	jiffies_to_timespec(-timeout, &delta);
+	set_normalized_timespec(&ts, kt.tv_sec + tomono.tv_sec - delta.tv_sec,
+				kt.tv_nsec + tomono.tv_nsec - delta.tv_nsec);
+	*expire_time = timespec_to_ktime(ts);
+	return true;
+}
+
 static int print_blocker_stat(struct seq_file *m,
 			      struct suspend_blocker *blocker)
 {
 	int lock_count = blocker->stat.count;
+	int expire_count = blocker->stat.expire_count;
 	ktime_t active_time = ktime_set(0, 0);
 	ktime_t total_time = blocker->stat.total_time;
 	ktime_t max_time = blocker->stat.max_time;
 	ktime_t prevent_suspend_time = blocker->stat.prevent_suspend_time;
 	if (blocker->flags & SB_ACTIVE) {
 		ktime_t now, add_time;
-		now = ktime_get();
+		bool expired = stats_get_expired_time(blocker, &now);
+		if (!expired)
+			now = ktime_get();
 		add_time = ktime_sub(now, blocker->stat.last_time);
 		lock_count++;
-		active_time = add_time;
+		if (!expired)
+			active_time = add_time;
+		else
+			expire_count++;
 		total_time = ktime_add(total_time, add_time);
 		if (blocker->flags & SB_PREVENTING_SUSPEND)
 			prevent_suspend_time = ktime_add(prevent_suspend_time,
@@ -86,9 +121,10 @@ static int print_blocker_stat(struct seq_file *m,
 			max_time = add_time;
 	}
 
-	return seq_printf(m, "\"%s\"\t%d\t%d\t%lld\t%lld\t%lld\t%lld\t%lld\n",
-		       blocker->name, lock_count, blocker->stat.wakeup_count,
-		       ktime_to_ns(active_time), ktime_to_ns(total_time),
+	return seq_printf(m, "\"%s\"\t%d\t%d\t%d\t%lld\t%lld\t%lld\t%lld\t"
+		       "%lld\n", blocker->name, lock_count, expire_count,
+		       blocker->stat.wakeup_count, ktime_to_ns(active_time),
+		       ktime_to_ns(total_time),
 		       ktime_to_ns(prevent_suspend_time), ktime_to_ns(max_time),
 		       ktime_to_ns(blocker->stat.last_time));
 }
@@ -99,7 +135,7 @@ static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
 	unsigned long irqflags;
 	struct suspend_blocker *blocker;
 
-	seq_puts(m, "name\tcount\twake_count\tactive_since"
+	seq_puts(m, "name\tcount\texpire_count\twake_count\tactive_since"
 		 "\ttotal_time\tsleep_time\tmax_time\tlast_change\n");
 	spin_lock_irqsave(&list_lock, irqflags);
 	list_for_each_entry(blocker, &inactive_blockers, link)
@@ -113,6 +149,7 @@ static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
 static void suspend_blocker_stat_init_locked(struct suspend_blocker *blocker)
 {
 	blocker->stat.count = 0;
+	blocker->stat.expire_count = 0;
 	blocker->stat.wakeup_count = 0;
 	blocker->stat.total_time = ktime_set(0, 0);
 	blocker->stat.prevent_suspend_time = ktime_set(0, 0);
@@ -125,6 +162,7 @@ static void suspend_blocker_stat_destroy_locked(struct suspend_blocker *bl)
 	if (!bl->stat.count)
 		return;
 	deleted_suspend_blockers.stat.count += bl->stat.count;
+	deleted_suspend_blockers.stat.expire_count += bl->stat.expire_count;
 	deleted_suspend_blockers.stat.total_time = ktime_add(
 		deleted_suspend_blockers.stat.total_time, bl->stat.total_time);
 	deleted_suspend_blockers.stat.prevent_suspend_time = ktime_add(
@@ -134,14 +172,20 @@ static void suspend_blocker_stat_destroy_locked(struct suspend_blocker *bl)
 		deleted_suspend_blockers.stat.max_time, bl->stat.max_time);
 }
 
-static void suspend_unblock_stat_locked(struct suspend_blocker *blocker)
+static void suspend_unblock_stat_locked(struct suspend_blocker *blocker,
+					bool expired)
 {
 	ktime_t duration;
 	ktime_t now;
 	if (!(blocker->flags & SB_ACTIVE))
 		return;
-	now = ktime_get();
+	if (stats_get_expired_time(blocker, &now))
+		expired = true;
+	else
+		now = ktime_get();
 	blocker->stat.count++;
+	if (expired)
+		blocker->stat.expire_count++;
 	duration = ktime_sub(now, blocker->stat.last_time);
 	blocker->stat.total_time =
 		ktime_add(blocker->stat.total_time, duration);
@@ -164,6 +208,12 @@ static void suspend_block_stat_locked(struct suspend_blocker *blocker)
 		wait_for_wakeup = false;
 		blocker->stat.wakeup_count++;
 	}
+	if ((blocker->flags & SB_AUTO_EXPIRE) &&
+	    time_is_before_eq_jiffies(blocker->expires)) {
+		suspend_unblock_stat_locked(blocker, false);
+		blocker->stat.last_time = ktime_get();
+	}
+
 	if (!(blocker->flags & SB_ACTIVE))
 		blocker->stat.last_time = ktime_get();
 }
@@ -171,17 +221,22 @@ static void suspend_block_stat_locked(struct suspend_blocker *blocker)
 static void update_sleep_wait_stats_locked(bool done)
 {
 	struct suspend_blocker *blocker;
-	ktime_t now, elapsed, add;
+	ktime_t now, etime, elapsed, add;
+	bool expired;
 
 	now = ktime_get();
 	elapsed = ktime_sub(now, last_sleep_time_update);
 	list_for_each_entry(blocker, &active_blockers, link) {
+		expired = stats_get_expired_time(blocker, &etime);
 		if (blocker->flags & SB_PREVENTING_SUSPEND) {
-			add = elapsed;
+			if (expired)
+				add = ktime_sub(etime, last_sleep_time_update);
+			else
+				add = elapsed;
 			blocker->stat.prevent_suspend_time = ktime_add(
 				blocker->stat.prevent_suspend_time, add);
 		}
-		if (done)
+		if (done || expired)
 			blocker->flags &= ~SB_PREVENTING_SUSPEND;
 		else
 			blocker->flags |= SB_PREVENTING_SUSPEND;
@@ -197,8 +252,8 @@ static inline void suspend_blocker_stat_destroy_locked(
 					struct suspend_blocker *blocker) {}
 static inline void suspend_block_stat_locked(
 					struct suspend_blocker *blocker) {}
-static inline void suspend_unblock_stat_locked(
-					struct suspend_blocker *blocker) {}
+static inline void suspend_unblock_stat_locked(struct suspend_blocker *blocker,
+					   bool expired) {}
 static inline void update_sleep_wait_stats_locked(bool done) {}
 
 static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
@@ -218,12 +273,50 @@ static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
 
 #endif
 
+static void expire_suspend_blocker(struct suspend_blocker *blocker)
+{
+	suspend_unblock_stat_locked(blocker, true);
+	blocker->flags &= ~(SB_ACTIVE | SB_AUTO_EXPIRE);
+	list_del(&blocker->link);
+	list_add(&blocker->link, &inactive_blockers);
+	if (debug_mask & (DEBUG_SUSPEND_BLOCKER | DEBUG_EXPIRE))
+		pr_info("expired suspend blocker %s\n", blocker->name);
+}
+
 static void print_active_blockers_locked(void)
 {
 	struct suspend_blocker *blocker;
 
-	list_for_each_entry(blocker, &active_blockers, link)
-		pr_info("active suspend blocker %s\n", blocker->name);
+	list_for_each_entry(blocker, &active_blockers, link) {
+		if (blocker->flags & SB_AUTO_EXPIRE) {
+			long timeout = blocker->expires - jiffies;
+			if (timeout <= 0)
+				pr_info("suspend blocker %s, expired\n",
+					blocker->name);
+			else
+				pr_info("active suspend blocker %s, time left "
+					"%ld\n", blocker->name, timeout);
+		} else
+			pr_info("active suspend blocker %s\n", blocker->name);
+	}
+}
+
+static long max_suspend_blocker_timeout_locked(void)
+{
+	struct suspend_blocker *blocker, *n;
+	long max_timeout = 0;
+
+	list_for_each_entry_safe(blocker, n, &active_blockers, link) {
+		if (blocker->flags & SB_AUTO_EXPIRE) {
+			long timeout = blocker->expires - jiffies;
+			if (timeout <= 0)
+				expire_suspend_blocker(blocker);
+			else if (timeout > max_timeout)
+				max_timeout = timeout;
+		} else
+			return -1;
+	}
+	return max_timeout;
 }
 
 /**
@@ -237,9 +330,14 @@ static void print_active_blockers_locked(void)
  */
 bool suspend_is_blocked(void)
 {
+	long ret;
+	unsigned long irqflags;
 	if (!enable_suspend_blockers)
 		return 0;
-	return !list_empty(&active_blockers);
+	spin_lock_irqsave(&list_lock, irqflags);
+	ret = !!max_suspend_blocker_timeout_locked();
+	spin_unlock_irqrestore(&list_lock, irqflags);
+	return ret;
 }
 
 static void suspend_worker(struct work_struct *work)
@@ -264,14 +362,49 @@ static void suspend_worker(struct work_struct *work)
 	if (current_event_num == entry_event_num) {
 		if (debug_mask & DEBUG_SUSPEND)
 			pr_info("suspend: pm_suspend returned with no event\n");
-		suspend_block(&unknown_wakeup);
-		suspend_unblock(&unknown_wakeup);
+		suspend_block_timeout(&unknown_wakeup, HZ / 2);
 	}
 abort:
 	enable_suspend_blockers = false;
 }
 static DECLARE_WORK(suspend_work, suspend_worker);
 
+static void expire_suspend_blockers(unsigned long data)
+{
+	long timeout;
+	unsigned long irqflags;
+	if (debug_mask & DEBUG_EXPIRE)
+		pr_info("expire_suspend_blockers: start\n");
+	spin_lock_irqsave(&list_lock, irqflags);
+	if (debug_mask & DEBUG_SUSPEND)
+		print_active_blockers_locked();
+	timeout = max_suspend_blocker_timeout_locked();
+	if (debug_mask & DEBUG_EXPIRE)
+		pr_info("expire_suspend_blockers: done, timeout %ld\n",
+			timeout);
+	if (timeout == 0)
+		queue_work(suspend_work_queue, &suspend_work);
+	spin_unlock_irqrestore(&list_lock, irqflags);
+}
+static DEFINE_TIMER(expire_timer, expire_suspend_blockers, 0, 0);
+
+static void update_suspend(struct suspend_blocker *blocker, long max_timeout)
+{
+	if (max_timeout > 0) {
+		if (debug_mask & DEBUG_EXPIRE)
+			pr_info("suspend_blocker: %s, start expire timer, "
+				"%ld\n", blocker->name, max_timeout);
+		mod_timer(&expire_timer, jiffies + max_timeout);
+	} else {
+		if (del_timer(&expire_timer))
+			if (debug_mask & DEBUG_EXPIRE)
+				pr_info("suspend_blocker: %s, stop expire "
+					"timer\n", blocker->name);
+		if (max_timeout == 0)
+			queue_work(suspend_work_queue, &suspend_work);
+	}
+}
+
 static int suspend_block_suspend(struct sys_device *dev, pm_message_t state)
 {
 	int ret = suspend_is_blocked() ? -EAGAIN : 0;
@@ -334,17 +467,14 @@ void suspend_blocker_destroy(struct suspend_blocker *blocker)
 	suspend_blocker_stat_destroy_locked(blocker);
 	blocker->flags &= ~SB_INITIALIZED;
 	list_del(&blocker->link);
-	if ((blocker->flags & SB_ACTIVE) && list_empty(&active_blockers))
-		queue_work(suspend_work_queue, &suspend_work);
+	if (blocker->flags & SB_ACTIVE)
+		update_suspend(blocker, max_suspend_blocker_timeout_locked());
 	spin_unlock_irqrestore(&list_lock, irqflags);
 }
 EXPORT_SYMBOL(suspend_blocker_destroy);
 
-/**
- * suspend_block() - Block suspend
- * @blocker:	The suspend blocker to use
- */
-void suspend_block(struct suspend_blocker *blocker)
+static void __suspend_block(struct suspend_blocker *blocker, long timeout,
+			    bool has_timeout)
 {
 	unsigned long irqflags;
 
@@ -355,20 +485,56 @@ void suspend_block(struct suspend_blocker *blocker)
 	suspend_block_stat_locked(blocker);
 	blocker->flags |= SB_ACTIVE;
 	list_del(&blocker->link);
-	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
-		pr_info("suspend_block: %s\n", blocker->name);
-	list_add(&blocker->link, &active_blockers);
+	if (has_timeout) {
+		if (debug_mask & DEBUG_SUSPEND_BLOCKER)
+			pr_info("suspend_block: %s, timeout %ld.%03lu\n",
+				blocker->name, timeout / HZ,
+				(timeout % HZ) * MSEC_PER_SEC / HZ);
+		blocker->expires = jiffies + timeout;
+		blocker->flags |= SB_AUTO_EXPIRE;
+		list_add_tail(&blocker->link, &active_blockers);
+	} else {
+		if (debug_mask & DEBUG_SUSPEND_BLOCKER)
+			pr_info("suspend_block: %s\n", blocker->name);
+		blocker->expires = LONG_MAX;
+		blocker->flags &= ~SB_AUTO_EXPIRE;
+		/* Add to head so suspend_is_blocked only has to examine */
+		/* one entry */
+		list_add(&blocker->link, &active_blockers);
+	}
 
 	current_event_num++;
 	if (blocker == &main_suspend_blocker)
 		update_sleep_wait_stats_locked(true);
 	else if (!suspend_blocker_is_active(&main_suspend_blocker))
 		update_sleep_wait_stats_locked(false);
+	update_suspend(blocker, has_timeout ?
+			max_suspend_blocker_timeout_locked() : -1);
 	spin_unlock_irqrestore(&list_lock, irqflags);
 }
+
+/**
+ * suspend_block() - Block suspend
+ * @blocker:	The suspend blocker to use
+ */
+void suspend_block(struct suspend_blocker *blocker)
+{
+	__suspend_block(blocker, 0, false);
+}
 EXPORT_SYMBOL(suspend_block);
 
 /**
+ * suspend_block_timeout() - Block suspend for a limited time
+ * @blocker:	The suspend blocker to use.
+ * @timeout:	Timeout in jiffies before the suspend blocker auto-unblock
+ */
+void suspend_block_timeout(struct suspend_blocker *blocker, long timeout)
+{
+	__suspend_block(blocker, timeout, true);
+}
+EXPORT_SYMBOL(suspend_block_timeout);
+
+/**
  * suspend_unblock() - Unblock suspend
  * @blocker:	The suspend blocker to unblock.
  *
@@ -383,16 +549,15 @@ void suspend_unblock(struct suspend_blocker *blocker)
 
 	spin_lock_irqsave(&list_lock, irqflags);
 
-	suspend_unblock_stat_locked(blocker);
+	suspend_unblock_stat_locked(blocker, false);
 
 	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
 		pr_info("suspend_unblock: %s\n", blocker->name);
+	blocker->flags &= ~(SB_ACTIVE | SB_AUTO_EXPIRE);
 	list_del(&blocker->link);
 	list_add(&blocker->link, &inactive_blockers);
 
-	if ((blocker->flags & SB_ACTIVE) && list_empty(&active_blockers))
-		queue_work(suspend_work_queue, &suspend_work);
-	blocker->flags &= ~(SB_ACTIVE);
+	update_suspend(blocker, max_suspend_blocker_timeout_locked());
 	if (blocker == &main_suspend_blocker) {
 		if (debug_mask & DEBUG_SUSPEND)
 			print_active_blockers_locked();
@@ -407,6 +572,10 @@ EXPORT_SYMBOL(suspend_unblock);
  * @blocker:	The suspend blocker to check.
  *
  * Returns true if the suspend_blocker is currently active.
+ *
+ * If the suspend_blocker has a timeout, it does not check the timeout, but if
+ * the timeout had already expired when it was checked elsewhere this function
+ * will return false.
  */
 bool suspend_blocker_is_active(struct suspend_blocker *blocker)
 {
-- 
1.6.1

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