[PATCH 9/9] PM: suspend_block: Add timeout support to user-space suspend_blockers

["Arve Hjønnevåg" <arve@android.com>]

This also allows a grace period to be set where suspend is blocked for a while
if a user-space suspend_blocker is destroyed while it was active.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 Documentation/power/suspend-blockers.txt |    7 +++++++
 include/linux/suspend_block_dev.h        |    1 +
 kernel/power/user_suspend_blocker.c      |   23 +++++++++++++++++++++++
 3 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txt
index fd9f932..747c163 100644
--- a/Documentation/power/suspend-blockers.txt
+++ b/Documentation/power/suspend-blockers.txt
@@ -113,6 +113,8 @@ then call:
 
 To activate a suspend_blocker call:
     ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK);
+or
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK_TIMEOUT, &timespec_timeout);
 
 To unblock call:
     ioctl(fd, SUSPEND_BLOCKER_IOCTL_UNBLOCK);
@@ -120,3 +122,8 @@ To unblock call:
 To destroy the suspend_blocker, close the device:
     close(fd);
 
+A module parameter, unclean_exit_grace_period, can be set to allow servers
+some time to restart if they crash with an active suspend_blocker. If the
+process dies or the device is closed while the suspend_blocker is active, a
+suspend_blocker will be held for the number of seconds specified.
+
diff --git a/include/linux/suspend_block_dev.h b/include/linux/suspend_block_dev.h
index a7c0bf9..cff4943 100644
--- a/include/linux/suspend_block_dev.h
+++ b/include/linux/suspend_block_dev.h
@@ -20,6 +20,7 @@
 
 #define SUSPEND_BLOCKER_IOCTL_INIT(len)		_IOC(_IOC_WRITE, 's', 0, len)
 #define SUSPEND_BLOCKER_IOCTL_BLOCK		_IO('s', 1)
+#define SUSPEND_BLOCKER_IOCTL_BLOCK_TIMEOUT	_IOW('s', 2, struct timespec)
 #define SUSPEND_BLOCKER_IOCTL_UNBLOCK		_IO('s', 3)
 
 #endif
diff --git a/kernel/power/user_suspend_blocker.c b/kernel/power/user_suspend_blocker.c
index 69b3ddb..b853f66 100644
--- a/kernel/power/user_suspend_blocker.c
+++ b/kernel/power/user_suspend_blocker.c
@@ -26,7 +26,12 @@ enum {
 static int debug_mask = DEBUG_FAILURE;
 module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
 
+static int unclean_exit_grace_period;
+module_param_named(unclean_exit_grace_period, unclean_exit_grace_period, int,
+						S_IRUGO | S_IWUSR | S_IWGRP);
+
 static DEFINE_MUTEX(ioctl_lock);
+static struct suspend_blocker unclean_exit_suspend_blocker;
 
 struct user_suspend_blocker {
 	struct suspend_blocker	blocker;
@@ -58,6 +63,8 @@ static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
 {
 	void __user *arg = (void __user *)_arg;
 	struct user_suspend_blocker *bl;
+	struct timespec ts;
+	unsigned long timeout;
 	long ret;
 
 	mutex_lock(&ioctl_lock);
@@ -75,6 +82,15 @@ static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
 		suspend_block(&bl->blocker);
 		ret = 0;
 		break;
+	case SUSPEND_BLOCKER_IOCTL_BLOCK_TIMEOUT:
+		if (copy_from_user(&ts, arg, sizeof(ts))) {
+			ret = -EFAULT;
+			goto done;
+		}
+		timeout  = timespec_to_jiffies(&ts);
+		suspend_block_timeout(&bl->blocker, timeout);
+		ret = 0;
+		break;
 	case SUSPEND_BLOCKER_IOCTL_UNBLOCK:
 		suspend_unblock(&bl->blocker);
 		ret = 0;
@@ -95,6 +111,10 @@ static int user_suspend_blocker_release(struct inode *inode, struct file *file)
 	struct user_suspend_blocker *bl = file->private_data;
 	if (!bl)
 		return 0;
+	if (suspend_blocker_is_active(&bl->blocker) &&
+	    unclean_exit_grace_period)
+		suspend_block_timeout(&unclean_exit_suspend_blocker,
+					unclean_exit_grace_period * HZ);
 	suspend_blocker_destroy(&bl->blocker);
 	kfree(bl);
 	return 0;
@@ -113,12 +133,15 @@ struct miscdevice user_suspend_blocker_device = {
 
 static int __init user_suspend_blocker_init(void)
 {
+	suspend_blocker_init(&unclean_exit_suspend_blocker,
+				"user-unclean-exit");
 	return misc_register(&user_suspend_blocker_device);
 }
 
 static void __exit user_suspend_blocker_exit(void)
 {
 	misc_deregister(&user_suspend_blocker_device);
+	suspend_blocker_destroy(&unclean_exit_suspend_blocker);
 }
 
 module_init(user_suspend_blocker_init);
-- 
1.6.1

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