[PATCH 2/8] PM: suspend_block: Add driver to access suspend blockers from user-space

Arve Hjønnevåg
2010-05-14T04:11:07Z

Add a misc device, "suspend_blocker", that allows user-space processes
to block auto suspend. The device has ioctls to create a suspend_blocker,
and to block and unblock suspend. To delete the suspend_blocker, close
the device.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
Documentation/ioctl/ioctl-number.txt | 3 +-
Documentation/power/opportunistic-suspend.txt | 27 +++++
include/linux/suspend_ioctls.h | 4 +
kernel/power/Kconfig | 7 ++
kernel/power/Makefile | 1 +
kernel/power/user_suspend_blocker.c | 143 +++++++++++++++++++++++++
6 files changed, 184 insertions(+), 1 deletions(-)
create mode 100644 kernel/power/user_suspend_blocker.c

diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index dd5806f..e2458f7 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -254,7 +254,8 @@ Code Seq#(hex) Include File Comments
'q' 80-FF linux/telephony.h Internet PhoneJACK, Internet LineJACK
linux/ixjuser.h <http://www.quicknet.net>
'r' 00-1F linux/msdos_fs.h and fs/fat/dir.c
-'s' all linux/cdk.h
+'s' all linux/cdk.h conflict!
+'s' all linux/suspend_block_dev.h conflict!
't' 00-7F linux/if_ppp.h
't' 80-8F linux/isdn_ppp.h
't' 90 linux/toshiba.h
diff --git a/Documentation/power/opportunistic-suspend.txt b/Documentation/power/opportunistic-suspend.txt
index 4bee7bc..93f4c24 100644
--- a/Documentation/power/opportunistic-suspend.txt
+++ b/Documentation/power/opportunistic-suspend.txt
@@ -127,3 +127,30 @@ if (list_empty(&state->pending_work))
suspend_unblock(&state->suspend_blocker);
else
suspend_block(&state->suspend_blocker);
+
+User space API
+==============
+
+To create a suspend blocker from user space, open the suspend_blocker special
+device file:
+
+ fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
+
+then optionally call:
+
+ ioctl(fd, SUSPEND_BLOCKER_IOCTL_SET_NAME(strlen(name)), name);
+
+To activate the suspend blocker call:
+
+ ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK);
+
+To deactivate it call:
+
+ ioctl(fd, SUSPEND_BLOCKER_IOCTL_UNBLOCK);
+
+To destroy the suspend blocker, close the device:
+
+ close(fd);
+
+If the first ioctl called is not SUSPEND_BLOCKER_IOCTL_SET_NAME the suspend
+blocker will get the default name "(userspace)".
diff --git a/include/linux/suspend_ioctls.h b/include/linux/suspend_ioctls.h
index 0b30382..b95a6b2 100644
--- a/include/linux/suspend_ioctls.h
+++ b/include/linux/suspend_ioctls.h
@@ -30,4 +30,8 @@ struct resume_swap_area {
#define SNAPSHOT_ALLOC_SWAP_PAGE _IOR(SNAPSHOT_IOC_MAGIC, 20, __kernel_loff_t)
#define SNAPSHOT_IOC_MAXNR 20

+#define SUSPEND_BLOCKER_IOCTL_SET_NAME(len) _IOC(_IOC_WRITE, 's', 0, len)
+#define SUSPEND_BLOCKER_IOCTL_BLOCK _IO('s', 1)
+#define SUSPEND_BLOCKER_IOCTL_UNBLOCK _IO('s', 2)
+
#endif /* _LINUX_SUSPEND_IOCTLS_H */
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 6d11a45..2e665cd 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -146,6 +146,13 @@ config OPPORTUNISTIC_SUSPEND
determines the sleep state the system will be put into when there are
no active suspend blockers.

+config USER_SUSPEND_BLOCKERS
+ bool "User space suspend blockers"
+ depends on OPPORTUNISTIC_SUSPEND
+ ---help---
+ User space suspend blockers API. Creates a misc device allowing user
+ space to create, use and destroy suspend blockers.
+
config HIBERNATION_NVS
bool

diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 95d8e6d..2015594 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_PM_SLEEP) += console.o
obj-$(CONFIG_FREEZER) += process.o
obj-$(CONFIG_SUSPEND) += suspend.o
obj-$(CONFIG_OPPORTUNISTIC_SUSPEND) += opportunistic_suspend.o
+obj-$(CONFIG_USER_SUSPEND_BLOCKERS) += user_suspend_blocker.o
obj-$(CONFIG_PM_TEST_SUSPEND) += suspend_test.o
obj-$(CONFIG_HIBERNATION) += hibernate.o snapshot.o swap.o user.o
obj-$(CONFIG_HIBERNATION_NVS) += hibernate_nvs.o
diff --git a/kernel/power/user_suspend_blocker.c b/kernel/power/user_suspend_blocker.c
new file mode 100644
index 0000000..d53f939
--- /dev/null
+++ b/kernel/power/user_suspend_blocker.c
@@ -0,0 +1,143 @@
+/*
+ * kernel/power/user_suspend_blocker.c
+ *
+ * Copyright (C) 2009-2010 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+#include <linux/suspend_ioctls.h>
+
+enum {
+ DEBUG_FAILURE = BIT(0),
+};
+static int debug_mask = DEBUG_FAILURE;
+module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
+
+static DEFINE_MUTEX(ioctl_lock);
+
+#define USER_SUSPEND_BLOCKER_NAME_LEN 31
+
+struct user_suspend_blocker {
+ struct suspend_blocker blocker;
+ char name[USER_SUSPEND_BLOCKER_NAME_LEN + 1];
+ bool registered;
+};
+
+static int user_suspend_blocker_open(struct inode *inode, struct file *filp)
+{
+ struct user_suspend_blocker *blocker;
+
+ blocker = kzalloc(sizeof(*blocker), GFP_KERNEL);
+ if (!blocker)
+ return -ENOMEM;
+
+ nonseekable_open(inode, filp);
+ strcpy(blocker->name, "(userspace)");
+ blocker->blocker.name = blocker->name;
+ filp->private_data = blocker;
+
+ return 0;
+}
+
+static int suspend_blocker_set_name(struct user_suspend_blocker *blocker,
+ void __user *name, size_t name_len)
+{
+ if (blocker->registered)
+ return -EBUSY;
+
+ if (name_len > USER_SUSPEND_BLOCKER_NAME_LEN)
+ name_len = USER_SUSPEND_BLOCKER_NAME_LEN;
+
+ if (copy_from_user(blocker->name, name, name_len))
+ return -EFAULT;
+ blocker->name[name_len] = '\0';
+
+ return 0;
+}
+
+static long user_suspend_blocker_ioctl(struct file *filp, unsigned int cmd,
+ unsigned long _arg)
+{
+ void __user *arg = (void __user *)_arg;
+ struct user_suspend_blocker *blocker = filp->private_data;
+ long ret = 0;
+
+ mutex_lock(&ioctl_lock);
+ if ((cmd & ~IOCSIZE_MASK) == SUSPEND_BLOCKER_IOCTL_SET_NAME(0)) {
+ ret = suspend_blocker_set_name(blocker, arg, _IOC_SIZE(cmd));
+ goto done;
+ }
+ if (!blocker->registered) {
+ suspend_blocker_register(&blocker->blocker);
+ blocker->registered = true;
+ }
+ switch (cmd) {
+ case SUSPEND_BLOCKER_IOCTL_BLOCK:
+ suspend_block(&blocker->blocker);
+ break;
+
+ case SUSPEND_BLOCKER_IOCTL_UNBLOCK:
+ suspend_unblock(&blocker->blocker);
+ break;
+
+ default:
+ ret = -ENOTTY;
+ }
+done:
+ if (ret && (debug_mask & DEBUG_FAILURE))
+ pr_err("user_suspend_blocker_ioctl: cmd %x failed, %ld\n",
+ cmd, ret);
+ mutex_unlock(&ioctl_lock);
+ return ret;
+}
+
+static int user_suspend_blocker_release(struct inode *inode, struct file *filp)
+{
+ struct user_suspend_blocker *blocker = filp->private_data;
+
+ if (blocker->registered)
+ suspend_blocker_unregister(&blocker->blocker);
+ kfree(blocker);
+
+ return 0;
+}
+
+const struct file_operations user_suspend_blocker_fops = {
+ .open = user_suspend_blocker_open,
+ .release = user_suspend_blocker_release,
+ .unlocked_ioctl = user_suspend_blocker_ioctl,
+};
+
+struct miscdevice user_suspend_blocker_device = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "suspend_blocker",
+ .fops = &user_suspend_blocker_fops,
+};
+
+static int __init user_suspend_blocker_init(void)
+{
+ return misc_register(&user_suspend_blocker_device);
+}
+
+static void __exit user_suspend_blocker_exit(void)
+{
+ misc_deregister(&user_suspend_blocker_device);
+}
+
+module_init(user_suspend_blocker_init);
+module_exit(user_suspend_blocker_exit);
--
1.6.5.1

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