[RFC][PATCH 0/9] Suspend block api (version 2)

[RFC][PATCH 0/9] Suspend block api (version 2)

[Arve Hjønnevåg]

This patch series adds a suspend-block api that provides the same
functionality as the android wakelock api. This patch series has
some documentation and code style fixes and it now uses debugfs
for stats. It also fixes some bugs in the user-space interface.

--
Arve Hjønnevåg 

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[PATCH 1/9] PM: Add suspend block api.

[Arve Hjønnevåg]

Adds /sys/power/request_state, a non-blocking interface that specifies
which suspend state to enter when no suspend blockers are active. A
special state, "on", stops the process by activating the "main" suspend
blocker.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 Documentation/power/suspend-blockers.txt |   95 +++++++++++
 include/linux/suspend_blocker.h          |   60 +++++++
 kernel/power/Kconfig                     |   10 +
 kernel/power/Makefile                    |    1 +
 kernel/power/main.c                      |   60 +++++++
 kernel/power/power.h                     |    6 +
 kernel/power/suspend_blocker.c           |  269 ++++++++++++++++++++++++++++++
 7 files changed, 501 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/power/suspend-blockers.txt
 create mode 100755 include/linux/suspend_blocker.h
 create mode 100644 kernel/power/suspend_blocker.c

diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txt
new file mode 100644
index 0000000..9248aa9
--- /dev/null
+++ b/Documentation/power/suspend-blockers.txt
@@ -0,0 +1,95 @@
+Suspend blockers
+================
+
+Suspend blockers provide a mechanism for device drivers and user-space processes
+to prevent the system from entering suspend. Only suspend states requested
+through /sys/power/request_state are prevented. Writing to /sys/power/state
+will ignore suspend blockers, and sleep states entered from idle are unaffected.
+
+To use a suspend blocker, a device driver needs a struct suspend_blocker object
+that has to be initialized with suspend_blocker_init. When no longer needed,
+the suspend blocker must be destroyed with suspend_blocker_destroy.
+
+A suspend blocker is activated using suspend_block, which prevents the system
+from entering suspend until the suspend blocker is deactivated with
+suspend_unblock. Many suspend blockers may be used simultaneously, and the
+system is prevented from entering suspend as long as at least one of them is
+active.
+
+If the suspend operation has already started when calling suspend_block on a
+suspend_blocker, it will abort the suspend operation as long it has not already
+reached the sysdev suspend stage. This means that calling suspend_block from an
+interrupt handler or a freezeable thread always works, but if you call
+suspend_block from a sysdev suspend handler you must also return an error from
+that handler to abort a suspend sequence that was already started.
+
+In cell phones or other embedded systems where powering the screen is a
+significant drain on the battery, suspend blockers can be used to allow
+user-space to decide whether a keystroke received while the system is suspended
+should cause the screen to be turned back on or allow the system to go back into
+suspend. Use set_irq_wake or a platform specific api to make sure the keypad
+interrupt wakes up the cpu. Once the keypad driver has resumed, the sequence of
+events can look like this:
+
+- The Keypad driver gets an interrupt. It then calls suspend_block on the
+  keypad-scan suspend_blocker and starts scanning the keypad matrix.
+- The keypad-scan code detects a key change and reports it to the input-event
+  driver.
+- The input-event driver sees the key change, enqueues an event, and calls
+  suspend_block on the input-event-queue suspend_blocker.
+- The keypad-scan code detects that no keys are held and calls suspend_unblock
+  on the keypad-scan suspend_blocker.
+- The user-space input-event thread returns from select/poll, calls
+  suspend_block on the process-input-events suspend_blocker and then calls read
+  on the input-event device.
+- The input-event driver dequeues the key-event and, since the queue is now
+  empty, it calls suspend_unblock on the input-event-queue suspend_blocker.
+- The user-space input-event thread returns from read. If it determines that
+  the key should leave the screen off, it calls suspend_unblock on the
+  process_input_events suspend_blocker and then calls select or poll. The
+  system will automatically suspend again, since now no suspend blockers are
+  active.
+
+                 Key pressed   Key released
+                     |             |
+keypad-scan          ++++++++++++++++++
+input-event-queue        +++          +++
+process-input-events       +++          +++
+
+
+Driver API
+==========
+
+A driver can use the suspend block api by adding a suspend_blocker variable to
+its state and calling suspend_blocker_init. For instance:
+struct state {
+	struct suspend_blocker suspend_blocker;
+}
+
+init() {
+	suspend_blocker_init(&state->suspend_blocker, "suspend-blocker-name");
+}
+
+Before freeing the memory, suspend_blocker_destroy must be called:
+
+uninit() {
+	suspend_blocker_destroy(&state->suspend_blocker);
+}
+
+When the driver determines that it needs to run (usually in an interrupt
+handler) it calls suspend_block:
+	suspend_block(&state->suspend_blocker);
+
+When it no longer needs to run it calls suspend_unblock:
+	suspend_unblock(&state->suspend_blocker);
+
+Calling suspend_block when the suspend blocker is active or suspend_unblock when
+it is not active has no effect. This allows drivers to update their state and
+call suspend suspend_block or suspend_unblock based on the result.
+For instance:
+
+if (list_empty(&state->pending_work))
+	suspend_unblock(&state->suspend_blocker);
+else
+	suspend_block(&state->suspend_blocker);
+
diff --git a/include/linux/suspend_blocker.h b/include/linux/suspend_blocker.h
new file mode 100755
index 0000000..21689cd
--- /dev/null
+++ b/include/linux/suspend_blocker.h
@@ -0,0 +1,60 @@
+/* include/linux/suspend_blocker.h
+ *
+ * Copyright (C) 2007-2009 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.
+ *
+ */
+
+#ifndef _LINUX_SUSPEND_BLOCKER_H
+#define _LINUX_SUSPEND_BLOCKER_H
+
+/**
+ * struct suspend_blocker - the basic suspend_blocker structure
+ * @flags:	Tracks initialized and active state.
+ * @name:	Name used for debugging.
+ *
+ * When a suspend_blocker is active it prevents the system from entering
+ * suspend.
+ *
+ * The suspend_blocker structure must be initialized by suspend_blocker_init()
+ */
+
+struct suspend_blocker {
+#ifdef CONFIG_SUSPEND_BLOCKERS
+	atomic_t            flags;
+	const char         *name;
+#endif
+};
+
+#ifdef CONFIG_SUSPEND_BLOCKERS
+
+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_unblock(struct suspend_blocker *blocker);
+bool suspend_blocker_is_active(struct suspend_blocker *blocker);
+bool suspend_is_blocked(void);
+
+#else
+
+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_unblock(struct suspend_blocker *blocker) {}
+static inline bool suspend_blocker_is_active(struct suspend_blocker *bl)
+								{ return 0; }
+static inline bool suspend_is_blocked(void) { return 0; }
+
+#endif
+
+#endif
+
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 23bd4da..a3587d3 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -116,6 +116,16 @@ config SUSPEND_FREEZER
 
 	  Turning OFF this setting is NOT recommended! If in doubt, say Y.
 
+config SUSPEND_BLOCKERS
+	bool "Suspend blockers"
+	depends on PM
+	select RTC_LIB
+	default n
+	---help---
+	  Enable suspend blockers. When user space requests a sleep state
+	  through /sys/power/request_state, the requested sleep state will be
+	  entered when no suspend blockers are active.
+
 config HIBERNATION
 	bool "Hibernation (aka 'suspend to disk')"
 	depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 720ea4f..e8c7f85 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -6,6 +6,7 @@ endif
 obj-$(CONFIG_PM)		+= main.o
 obj-$(CONFIG_PM_SLEEP)		+= console.o
 obj-$(CONFIG_FREEZER)		+= process.o
+obj-$(CONFIG_SUSPEND_BLOCKERS)	+= suspend_blocker.o
 obj-$(CONFIG_HIBERNATION)	+= swsusp.o disk.o snapshot.o swap.o user.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
diff --git a/kernel/power/main.c b/kernel/power/main.c
index c9632f8..4681c1e 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -22,6 +22,7 @@
 #include <linux/freezer.h>
 #include <linux/vmstat.h>
 #include <linux/syscalls.h>
+#include <linux/suspend_blocker.h>
 
 #include "power.h"
 
@@ -392,6 +393,7 @@ static void suspend_finish(void)
 
 
 static const char * const pm_states[PM_SUSPEND_MAX] = {
+	[PM_SUSPEND_ON]		= "on",
 	[PM_SUSPEND_STANDBY]	= "standby",
 	[PM_SUSPEND_MEM]	= "mem",
 };
@@ -540,6 +542,61 @@ static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 
 power_attr(state);
 
+/**
+ *	request_state - control system power state.
+ *
+ *	This is similar to state, but it does not block until the system
+ *	resumes, and it will try to re-enter the state until another state is
+ *	requested. Suspend blockers are respected and the requested state will
+ *	only be entered when no suspend blockers are active.
+ *	Write "on" to cancel.
+ */
+
+#ifdef CONFIG_SUSPEND_BLOCKERS
+static ssize_t request_state_show(struct kobject *kobj,
+				  struct kobj_attribute *attr, char *buf)
+{
+	char *s = buf;
+	int i;
+
+	for (i = 0; i < PM_SUSPEND_MAX; i++) {
+		if (pm_states[i] && (i == PM_SUSPEND_ON || valid_state(i)))
+			s += sprintf(s, "%s ", pm_states[i]);
+	}
+	if (s != buf)
+		/* convert the last space to a newline */
+		*(s-1) = '\n';
+	return (s - buf);
+}
+
+static ssize_t request_state_store(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   const char *buf, size_t n)
+{
+	suspend_state_t state = PM_SUSPEND_ON;
+	const char * const *s;
+	char *p;
+	int len;
+	int error = -EINVAL;
+
+	p = memchr(buf, '\n', n);
+	len = p ? p - buf : n;
+
+	for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
+		if (*s && len == strlen(*s) && !strncmp(buf, *s, len))
+			break;
+	}
+	if (state < PM_SUSPEND_MAX && *s)
+		if (state == PM_SUSPEND_ON || valid_state(state)) {
+			error = 0;
+			request_suspend_state(state);
+		}
+	return error ? error : n;
+}
+
+power_attr(request_state);
+#endif /* CONFIG_SUSPEND_BLOCKERS */
+
 #ifdef CONFIG_PM_TRACE
 int pm_trace_enabled;
 
@@ -567,6 +624,9 @@ power_attr(pm_trace);
 
 static struct attribute * g[] = {
 	&state_attr.attr,
+#ifdef CONFIG_SUSPEND_BLOCKERS
+	&request_state_attr.attr,
+#endif
 #ifdef CONFIG_PM_TRACE
 	&pm_trace_attr.attr,
 #endif
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 46b5ec7..609e01e 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -223,3 +223,9 @@ static inline void suspend_thaw_processes(void)
 {
 }
 #endif
+
+#ifdef CONFIG_SUSPEND_BLOCKERS
+/* kernel/power/suspend_block.c */
+void request_suspend_state(suspend_state_t state);
+#endif
+
diff --git a/kernel/power/suspend_blocker.c b/kernel/power/suspend_blocker.c
new file mode 100644
index 0000000..642b0db
--- /dev/null
+++ b/kernel/power/suspend_blocker.c
@@ -0,0 +1,269 @@
+/* kernel/power/suspend_blocker.c
+ *
+ * Copyright (C) 2005-2008 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/module.h>
+#include <linux/rtc.h>
+#include <linux/suspend.h>
+#include <linux/suspend_blocker.h>
+#include <linux/sysdev.h>
+#include "power.h"
+
+enum {
+	DEBUG_EXIT_SUSPEND = 1U << 0,
+	DEBUG_WAKEUP = 1U << 1,
+	DEBUG_USER_STATE = 1U << 2,
+	DEBUG_SUSPEND = 1U << 3,
+	DEBUG_SUSPEND_BLOCKER = 1U << 4,
+};
+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)
+
+static DEFINE_SPINLOCK(state_lock);
+static atomic_t suspend_block_count;
+static atomic_t current_event_num;
+struct workqueue_struct *suspend_work_queue;
+struct suspend_blocker main_suspend_blocker;
+static suspend_state_t requested_suspend_state = PM_SUSPEND_MEM;
+static bool enable_suspend_blockers;
+
+#define pr_info_time(fmt, args...) \
+	do { \
+		struct timespec ts; \
+		struct rtc_time tm; \
+		getnstimeofday(&ts); \
+		rtc_time_to_tm(ts.tv_sec, &tm); \
+		pr_info(fmt "(%d-%02d-%02d %02d:%02d:%02d.%09lu UTC)\n" , \
+			args, \
+			tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, \
+			tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec); \
+	} while (0);
+
+/**
+ * suspend_is_blocked() - Check if suspend should be blocked
+ *
+ * suspend_is_blocked can be used by generic power management code to abort
+ * suspend.
+ *
+ * To preserve backward compatibility suspend_is_blocked returns 0 unless it
+ * is called during suspend initiated from the suspend_block code.
+ */
+bool suspend_is_blocked(void)
+{
+	if (!enable_suspend_blockers)
+		return 0;
+	return !!atomic_read(&suspend_block_count);
+}
+
+static void suspend_worker(struct work_struct *work)
+{
+	int ret;
+	int entry_event_num;
+
+	enable_suspend_blockers = true;
+
+retry:
+	if (suspend_is_blocked()) {
+		if (debug_mask & DEBUG_SUSPEND)
+			pr_info("suspend: abort suspend\n");
+		goto abort;
+	}
+
+	entry_event_num = atomic_read(&current_event_num);
+	if (debug_mask & DEBUG_SUSPEND)
+		pr_info("suspend: enter suspend\n");
+	ret = pm_suspend(requested_suspend_state);
+	if (debug_mask & DEBUG_EXIT_SUSPEND)
+		pr_info_time("suspend: exit suspend, ret = %d ", ret);
+	if (atomic_read(&current_event_num) == entry_event_num) {
+		if (debug_mask & DEBUG_SUSPEND)
+			pr_info("suspend: pm_suspend returned with no event\n");
+		goto retry;
+	}
+abort:
+	enable_suspend_blockers = false;
+}
+static DECLARE_WORK(suspend_work, suspend_worker);
+
+static int suspend_block_suspend(struct sys_device *dev, pm_message_t state)
+{
+	int ret = suspend_is_blocked() ? -EAGAIN : 0;
+	if (debug_mask & DEBUG_SUSPEND)
+		pr_info("suspend_block_suspend return %d\n", ret);
+	return ret;
+}
+
+static struct sysdev_class suspend_block_sysclass = {
+	.name = "suspend_block",
+	.suspend = suspend_block_suspend,
+};
+static struct sys_device suspend_block_sysdev = {
+	.cls = &suspend_block_sysclass,
+};
+
+/**
+ * suspend_blocker_init() - Initialize a suspend blocker
+ * @blocker:	The suspend blocker to initialize.
+ * @name:	The name of the suspend blocker to show in debug messages.
+ *
+ * The suspend blocker struct and name must not be freed before calling
+ * suspend_blocker_destroy.
+ */
+void suspend_blocker_init(struct suspend_blocker *blocker, const char *name)
+{
+	WARN_ON(!name);
+
+	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
+		pr_info("suspend_blocker_init name=%s\n", name);
+
+	blocker->name = name;
+	atomic_set(&blocker->flags, SB_INITIALIZED);
+}
+EXPORT_SYMBOL(suspend_blocker_init);
+
+/**
+ * suspend_blocker_destroy() - Destroy a suspend blocker
+ * @blocker:	The suspend blocker to destroy.
+ */
+void suspend_blocker_destroy(struct suspend_blocker *blocker)
+{
+	int flags;
+	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
+		pr_info("suspend_blocker_destroy name=%s\n", blocker->name);
+	flags = atomic_xchg(&blocker->flags, 0);
+	WARN(!(flags & SB_INITIALIZED), "suspend_blocker_destroy called on "
+					"uninitialized suspend_blocker\n");
+	if (flags == (SB_INITIALIZED | SB_ACTIVE))
+		if (atomic_dec_and_test(&suspend_block_count))
+			queue_work(suspend_work_queue, &suspend_work);
+}
+EXPORT_SYMBOL(suspend_blocker_destroy);
+
+/**
+ * suspend_block() - Block suspend
+ * @blocker:	The suspend blocker to use
+ */
+void suspend_block(struct suspend_blocker *blocker)
+{
+	WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));
+
+	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
+		pr_info("suspend_block: %s\n", blocker->name);
+	if (atomic_cmpxchg(&blocker->flags, SB_INITIALIZED,
+	    SB_INITIALIZED | SB_ACTIVE) == SB_INITIALIZED)
+		atomic_inc(&suspend_block_count);
+
+	atomic_inc(&current_event_num);
+}
+EXPORT_SYMBOL(suspend_block);
+
+/**
+ * suspend_unblock() - Unblock suspend
+ * @blocker:	The suspend blocker to unblock.
+ *
+ * If no other suspend blockers block suspend, the system will suspend.
+ */
+void suspend_unblock(struct suspend_blocker *blocker)
+{
+	WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));
+
+	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
+		pr_info("suspend_unblock: %s\n", blocker->name);
+
+	if (atomic_cmpxchg(&blocker->flags, SB_INITIALIZED | SB_ACTIVE,
+	    SB_INITIALIZED) == (SB_INITIALIZED | SB_ACTIVE))
+		if (atomic_dec_and_test(&suspend_block_count))
+			queue_work(suspend_work_queue, &suspend_work);
+}
+EXPORT_SYMBOL(suspend_unblock);
+
+/**
+ * suspend_blocker_is_active() - Test if a suspend blocker is blocking suspend
+ * @blocker:	The suspend blocker to check.
+ *
+ * Returns true if the suspend_blocker is currently active.
+ */
+bool suspend_blocker_is_active(struct suspend_blocker *blocker)
+{
+	WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));
+
+	return !!(atomic_read(&blocker->flags) & SB_ACTIVE);
+}
+EXPORT_SYMBOL(suspend_blocker_is_active);
+
+void request_suspend_state(suspend_state_t state)
+{
+	unsigned long irqflags;
+	spin_lock_irqsave(&state_lock, irqflags);
+	if (debug_mask & DEBUG_USER_STATE)
+		pr_info_time("request_suspend_state: %s (%d->%d) at %lld ",
+			     state != PM_SUSPEND_ON ? "sleep" : "wakeup",
+			     requested_suspend_state, state,
+			     ktime_to_ns(ktime_get()));
+	requested_suspend_state = state;
+	if (state == PM_SUSPEND_ON)
+		suspend_block(&main_suspend_blocker);
+	else
+		suspend_unblock(&main_suspend_blocker);
+	spin_unlock_irqrestore(&state_lock, irqflags);
+}
+
+static int __init suspend_block_init(void)
+{
+	int ret;
+
+	suspend_blocker_init(&main_suspend_blocker, "main");
+	suspend_block(&main_suspend_blocker);
+
+	ret = sysdev_class_register(&suspend_block_sysclass);
+	if (ret) {
+		pr_err("suspend_block_init: sysdev_class_register failed\n");
+		goto err_sysdev_class_register;
+	}
+	ret = sysdev_register(&suspend_block_sysdev);
+	if (ret) {
+		pr_err("suspend_block_init: suspend_block_sysdev failed\n");
+		goto err_sysdev_register;
+	}
+
+	suspend_work_queue = create_singlethread_workqueue("suspend");
+	if (suspend_work_queue == NULL) {
+		ret = -ENOMEM;
+		goto err_suspend_work_queue;
+	}
+
+	return 0;
+
+err_suspend_work_queue:
+	sysdev_unregister(&suspend_block_sysdev);
+err_sysdev_register:
+	sysdev_class_unregister(&suspend_block_sysclass);
+err_sysdev_class_register:
+	suspend_blocker_destroy(&main_suspend_blocker);
+	return ret;
+}
+
+static void  __exit suspend_block_exit(void)
+{
+	destroy_workqueue(suspend_work_queue);
+	sysdev_unregister(&suspend_block_sysdev);
+	sysdev_class_unregister(&suspend_block_sysclass);
+	suspend_blocker_destroy(&main_suspend_blocker);
+}
+
+core_initcall(suspend_block_init);
+module_exit(suspend_block_exit);
-- 
1.6.1

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[PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

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/power/suspend-blockers.txt |   17 ++++
 include/linux/suspend_block_dev.h        |   25 ++++++
 kernel/power/Kconfig                     |    9 ++
 kernel/power/Makefile                    |    1 +
 kernel/power/user_suspend_blocker.c      |  125 ++++++++++++++++++++++++++++++
 5 files changed, 177 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/suspend_block_dev.h
 create mode 100644 kernel/power/user_suspend_blocker.c

diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txt
index 9248aa9..d81e20e 100644
--- a/Documentation/power/suspend-blockers.txt
+++ b/Documentation/power/suspend-blockers.txt
@@ -93,3 +93,20 @@ if (list_empty(&state->pending_work))
 else
 	suspend_block(&state->suspend_blocker);
 
+User-space API
+==============
+
+To create a suspend_blocker from user-space, open the suspend_blocker device:
+    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
+then call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
+
+To activate a suspend_blocker call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK);
+
+To unblock call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_UNBLOCK);
+
+To destroy the suspend_blocker, close the device:
+    close(fd);
+
diff --git a/include/linux/suspend_block_dev.h b/include/linux/suspend_block_dev.h
new file mode 100644
index 0000000..a7c0bf9
--- /dev/null
+++ b/include/linux/suspend_block_dev.h
@@ -0,0 +1,25 @@
+/* include/linux/suspend_block_dev.h
+ *
+ * Copyright (C) 2009 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.
+ *
+ */
+
+#ifndef _LINUX_SUSPEND_BLOCK_DEV_H
+#define _LINUX_SUSPEND_BLOCK_DEV_H
+
+#include <linux/ioctl.h>
+
+#define SUSPEND_BLOCKER_IOCTL_INIT(len)		_IOC(_IOC_WRITE, 's', 0, len)
+#define SUSPEND_BLOCKER_IOCTL_BLOCK		_IO('s', 1)
+#define SUSPEND_BLOCKER_IOCTL_UNBLOCK		_IO('s', 3)
+
+#endif
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index a3587d3..84b423f 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -126,6 +126,15 @@ config SUSPEND_BLOCKERS
 	  through /sys/power/request_state, the requested sleep state will be
 	  entered when no suspend blockers are active.
 
+config USER_SUSPEND_BLOCKERS
+	bool "Userspace suspend blockers"
+	depends on SUSPEND_BLOCKERS
+	default y
+	---help---
+	  User-space suspend block api. Creates a misc device with ioctls
+	  to create, block and unblock a suspend_blocker. The suspend_blocker
+	  will be deleted when the device is closed.
+
 config HIBERNATION
 	bool "Hibernation (aka 'suspend to disk')"
 	depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index e8c7f85..24ade91 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_PM)		+= main.o
 obj-$(CONFIG_PM_SLEEP)		+= console.o
 obj-$(CONFIG_FREEZER)		+= process.o
 obj-$(CONFIG_SUSPEND_BLOCKERS)	+= suspend_blocker.o
+obj-$(CONFIG_USER_SUSPEND_BLOCKERS)	+= user_suspend_blocker.o
 obj-$(CONFIG_HIBERNATION)	+= swsusp.o disk.o snapshot.o swap.o user.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
diff --git a/kernel/power/user_suspend_blocker.c b/kernel/power/user_suspend_blocker.c
new file mode 100644
index 0000000..69b3ddb
--- /dev/null
+++ b/kernel/power/user_suspend_blocker.c
@@ -0,0 +1,125 @@
+/* kernel/power/user_suspend_block.c
+ *
+ * Copyright (C) 2009 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/suspend_blocker.h>
+#include <linux/suspend_block_dev.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);
+
+struct user_suspend_blocker {
+	struct suspend_blocker	blocker;
+	char			name[0];
+};
+
+static int create_user_suspend_blocker(struct file *file, void __user *name,
+				 size_t name_len)
+{
+	struct user_suspend_blocker *bl;
+	if (file->private_data)
+		return -EBUSY;
+	bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
+	if (!bl)
+		return -ENOMEM;
+	if (copy_from_user(bl->name, name, name_len))
+		goto err_fault;
+	suspend_blocker_init(&bl->blocker, bl->name);
+	file->private_data = bl;
+	return 0;
+
+err_fault:
+	kfree(bl);
+	return -EFAULT;
+}
+
+static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
+				unsigned long _arg)
+{
+	void __user *arg = (void __user *)_arg;
+	struct user_suspend_blocker *bl;
+	long ret;
+
+	mutex_lock(&ioctl_lock);
+	if ((cmd & ~IOCSIZE_MASK) == SUSPEND_BLOCKER_IOCTL_INIT(0)) {
+		ret = create_user_suspend_blocker(file, arg, _IOC_SIZE(cmd));
+		goto done;
+	}
+	bl = file->private_data;
+	if (!bl) {
+		ret = -ENOENT;
+		goto done;
+	}
+	switch (cmd) {
+	case SUSPEND_BLOCKER_IOCTL_BLOCK:
+		suspend_block(&bl->blocker);
+		ret = 0;
+		break;
+	case SUSPEND_BLOCKER_IOCTL_UNBLOCK:
+		suspend_unblock(&bl->blocker);
+		ret = 0;
+		break;
+	default:
+		ret = -ENOTSUPP;
+	}
+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 *file)
+{
+	struct user_suspend_blocker *bl = file->private_data;
+	if (!bl)
+		return 0;
+	suspend_blocker_destroy(&bl->blocker);
+	kfree(bl);
+	return 0;
+}
+
+const struct file_operations user_suspend_blocker_fops = {
+	.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);
-- 
1.6.1

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[PATCH 3/9] PM: suspend_block: Abort task freezing if a suspend_blocker is active.

[Arve Hjønnevåg]

If a suspend_blocker is active, suspend will fail anyway. Since
try_to_freeze_tasks can take up to 20 seconds to complete or fail, aborting
as soon as someone blocks suspend (e.g. from an interrupt handler) improves
the worst case wakeup latency.

On an older kernel where task freezing could fail for processes attached
to a debugger, this fixed a problem where the device sometimes hung for
20 seconds before the screen turned on.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 kernel/power/process.c |   20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/kernel/power/process.c b/kernel/power/process.c
index ca63401..8c7c323 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/syscalls.h>
 #include <linux/freezer.h>
+#include <linux/suspend_blocker.h>
 
 /* 
  * Timeout for stopping processes
@@ -36,6 +37,7 @@ static int try_to_freeze_tasks(bool sig_only)
 	struct timeval start, end;
 	u64 elapsed_csecs64;
 	unsigned int elapsed_csecs;
+	bool wakeup = false;
 
 	do_gettimeofday(&start);
 
@@ -62,6 +64,10 @@ static int try_to_freeze_tasks(bool sig_only)
 		} while_each_thread(g, p);
 		read_unlock(&tasklist_lock);
 		yield();			/* Yield is okay here */
+		if (todo && suspend_is_blocked()) {
+			wakeup = true;
+			break;
+		}
 		if (time_after(jiffies, end_time))
 			break;
 	} while (todo);
@@ -78,10 +84,16 @@ static int try_to_freeze_tasks(bool sig_only)
 		 * but it cleans up leftover PF_FREEZE requests.
 		 */
 		printk("\n");
-		printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
-				"(%d tasks refusing to freeze):\n",
-				elapsed_csecs / 100, elapsed_csecs % 100, todo);
-		show_state();
+		if (wakeup) {
+			printk(KERN_ERR "Freezing of %s aborted\n",
+					sig_only ? "user space " : "tasks ");
+		} else {
+			printk(KERN_ERR
+			       "Freezing of tasks failed after %d.%02d seconds "
+			       "(%d tasks refusing to freeze):\n",
+			       elapsed_csecs / 100, elapsed_csecs % 100, todo);
+			show_state();
+		}
 		read_lock(&tasklist_lock);
 		do_each_thread(g, p) {
 			task_lock(p);
-- 
1.6.1

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[PATCH 4/9] Input: Block suspend while event queue is not empty.

[Arve Hjønnevåg]

Add an ioctl, EVIOCSSUSPENDBLOCK, to enable a suspend_blocker that will block
suspend while the event queue is not empty. This allows userspace code to
process input events while the device appears to be asleep.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 drivers/input/evdev.c |   22 ++++++++++++++++++++++
 include/linux/input.h |    3 +++
 2 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index ed8baa0..f07ac06 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -19,6 +19,7 @@
 #include <linux/input.h>
 #include <linux/major.h>
 #include <linux/device.h>
+#include <linux/suspend_blocker.h>
 #include "input-compat.h"
 
 struct evdev {
@@ -43,6 +44,8 @@ struct evdev_client {
 	struct fasync_struct *fasync;
 	struct evdev *evdev;
 	struct list_head node;
+	struct suspend_blocker suspend_blocker;
+	bool use_suspend_blocker;
 };
 
 static struct evdev *evdev_table[EVDEV_MINORS];
@@ -55,6 +58,8 @@ static void evdev_pass_event(struct evdev_client *client,
 	 * Interrupts are disabled, just acquire the lock
 	 */
 	spin_lock(&client->buffer_lock);
+	if (client->use_suspend_blocker)
+		suspend_block(&client->suspend_blocker);
 	client->buffer[client->head++] = *event;
 	client->head &= EVDEV_BUFFER_SIZE - 1;
 	spin_unlock(&client->buffer_lock);
@@ -236,6 +241,8 @@ static int evdev_release(struct inode *inode, struct file *file)
 	mutex_unlock(&evdev->mutex);
 
 	evdev_detach_client(evdev, client);
+	if (client->use_suspend_blocker)
+		suspend_blocker_destroy(&client->suspend_blocker);
 	kfree(client);
 
 	evdev_close_device(evdev);
@@ -335,6 +342,8 @@ static int evdev_fetch_next_event(struct evdev_client *client,
 	if (have_event) {
 		*event = client->buffer[client->tail++];
 		client->tail &= EVDEV_BUFFER_SIZE - 1;
+		if (client->use_suspend_blocker && client->head == client->tail)
+			suspend_unblock(&client->suspend_blocker);
 	}
 
 	spin_unlock_irq(&client->buffer_lock);
@@ -585,6 +594,19 @@ static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 		else
 			return evdev_ungrab(evdev, client);
 
+	case EVIOCGSUSPENDBLOCK:
+		return put_user(client->use_suspend_blocker, ip);
+
+	case EVIOCSSUSPENDBLOCK:
+		spin_lock_irq(&client->buffer_lock);
+		if (!client->use_suspend_blocker && p)
+			suspend_blocker_init(&client->suspend_blocker, "evdev");
+		else if (client->use_suspend_blocker && !p)
+			suspend_blocker_destroy(&client->suspend_blocker);
+		client->use_suspend_blocker = !!p;
+		spin_unlock_irq(&client->buffer_lock);
+		return 0;
+
 	default:
 
 		if (_IOC_TYPE(cmd) != 'E')
diff --git a/include/linux/input.h b/include/linux/input.h
index 1249a0c..67e2332 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -81,6 +81,9 @@ struct input_absinfo {
 
 #define EVIOCGRAB		_IOW('E', 0x90, int)			/* Grab/Release device */
 
+#define EVIOCGSUSPENDBLOCK	_IOR('E', 0x91, int)			/* get suspend block enable */
+#define EVIOCSSUSPENDBLOCK	_IOW('E', 0x91, int)			/* set suspend block enable */
+
 /*
  * Event types
  */
-- 
1.6.1

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[PATCH 5/9] PM: suspend_block: Switch to list of active and inactive suspend blockers

[Arve Hjønnevåg]

This allows active suspend blockers to be listed

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 include/linux/suspend_blocker.h |    6 ++-
 kernel/power/suspend_blocker.c  |   85 +++++++++++++++++++++++++++-----------
 2 files changed, 65 insertions(+), 26 deletions(-)

diff --git a/include/linux/suspend_blocker.h b/include/linux/suspend_blocker.h
index 21689cd..1faa433 100755
--- a/include/linux/suspend_blocker.h
+++ b/include/linux/suspend_blocker.h
@@ -16,8 +16,11 @@
 #ifndef _LINUX_SUSPEND_BLOCKER_H
 #define _LINUX_SUSPEND_BLOCKER_H
 
+#include <linux/list.h>
+
 /**
  * struct suspend_blocker - the basic suspend_blocker structure
+ * @link:	List entry for active or inactive list.
  * @flags:	Tracks initialized and active state.
  * @name:	Name used for debugging.
  *
@@ -29,7 +32,8 @@
 
 struct suspend_blocker {
 #ifdef CONFIG_SUSPEND_BLOCKERS
-	atomic_t            flags;
+	struct list_head    link;
+	int                 flags;
 	const char         *name;
 #endif
 };
diff --git a/kernel/power/suspend_blocker.c b/kernel/power/suspend_blocker.c
index 642b0db..94832ca 100644
--- a/kernel/power/suspend_blocker.c
+++ b/kernel/power/suspend_blocker.c
@@ -33,9 +33,11 @@ module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
 #define SB_INITIALIZED            (1U << 8)
 #define SB_ACTIVE                 (1U << 9)
 
+static DEFINE_SPINLOCK(list_lock);
 static DEFINE_SPINLOCK(state_lock);
-static atomic_t suspend_block_count;
-static atomic_t current_event_num;
+static LIST_HEAD(inactive_blockers);
+static LIST_HEAD(active_blockers);
+static int current_event_num;
 struct workqueue_struct *suspend_work_queue;
 struct suspend_blocker main_suspend_blocker;
 static suspend_state_t requested_suspend_state = PM_SUSPEND_MEM;
@@ -53,6 +55,14 @@ static bool enable_suspend_blockers;
 			tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec); \
 	} while (0);
 
+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);
+}
+
 /**
  * suspend_is_blocked() - Check if suspend should be blocked
  *
@@ -66,7 +76,7 @@ bool suspend_is_blocked(void)
 {
 	if (!enable_suspend_blockers)
 		return 0;
-	return !!atomic_read(&suspend_block_count);
+	return !list_empty(&active_blockers);
 }
 
 static void suspend_worker(struct work_struct *work)
@@ -83,13 +93,13 @@ retry:
 		goto abort;
 	}
 
-	entry_event_num = atomic_read(&current_event_num);
+	entry_event_num = current_event_num;
 	if (debug_mask & DEBUG_SUSPEND)
 		pr_info("suspend: enter suspend\n");
 	ret = pm_suspend(requested_suspend_state);
 	if (debug_mask & DEBUG_EXIT_SUSPEND)
 		pr_info_time("suspend: exit suspend, ret = %d ", ret);
-	if (atomic_read(&current_event_num) == entry_event_num) {
+	if (current_event_num == entry_event_num) {
 		if (debug_mask & DEBUG_SUSPEND)
 			pr_info("suspend: pm_suspend returned with no event\n");
 		goto retry;
@@ -125,13 +135,20 @@ static struct sys_device suspend_block_sysdev = {
  */
 void suspend_blocker_init(struct suspend_blocker *blocker, const char *name)
 {
+	unsigned long irqflags = 0;
+
 	WARN_ON(!name);
 
 	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
 		pr_info("suspend_blocker_init name=%s\n", name);
 
 	blocker->name = name;
-	atomic_set(&blocker->flags, SB_INITIALIZED);
+	blocker->flags = SB_INITIALIZED;
+	INIT_LIST_HEAD(&blocker->link);
+
+	spin_lock_irqsave(&list_lock, irqflags);
+	list_add(&blocker->link, &inactive_blockers);
+	spin_unlock_irqrestore(&list_lock, irqflags);
 }
 EXPORT_SYMBOL(suspend_blocker_init);
 
@@ -141,15 +158,17 @@ EXPORT_SYMBOL(suspend_blocker_init);
  */
 void suspend_blocker_destroy(struct suspend_blocker *blocker)
 {
-	int flags;
+	unsigned long irqflags;
+	if (WARN_ON(!(blocker->flags & SB_INITIALIZED)))
+		return;
 	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
 		pr_info("suspend_blocker_destroy name=%s\n", blocker->name);
-	flags = atomic_xchg(&blocker->flags, 0);
-	WARN(!(flags & SB_INITIALIZED), "suspend_blocker_destroy called on "
-					"uninitialized suspend_blocker\n");
-	if (flags == (SB_INITIALIZED | SB_ACTIVE))
-		if (atomic_dec_and_test(&suspend_block_count))
-			queue_work(suspend_work_queue, &suspend_work);
+	spin_lock_irqsave(&list_lock, irqflags);
+	blocker->flags &= ~SB_INITIALIZED;
+	list_del(&blocker->link);
+	if ((blocker->flags & SB_ACTIVE) && list_empty(&active_blockers))
+		queue_work(suspend_work_queue, &suspend_work);
+	spin_unlock_irqrestore(&list_lock, irqflags);
 }
 EXPORT_SYMBOL(suspend_blocker_destroy);
 
@@ -159,15 +178,20 @@ EXPORT_SYMBOL(suspend_blocker_destroy);
  */
 void suspend_block(struct suspend_blocker *blocker)
 {
-	WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));
+	unsigned long irqflags;
+
+	if (WARN_ON(!(blocker->flags & SB_INITIALIZED)))
+		return;
 
+	spin_lock_irqsave(&list_lock, irqflags);
+	blocker->flags |= SB_ACTIVE;
+	list_del(&blocker->link);
 	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
 		pr_info("suspend_block: %s\n", blocker->name);
-	if (atomic_cmpxchg(&blocker->flags, SB_INITIALIZED,
-	    SB_INITIALIZED | SB_ACTIVE) == SB_INITIALIZED)
-		atomic_inc(&suspend_block_count);
+	list_add(&blocker->link, &active_blockers);
 
-	atomic_inc(&current_event_num);
+	current_event_num++;
+	spin_unlock_irqrestore(&list_lock, irqflags);
 }
 EXPORT_SYMBOL(suspend_block);
 
@@ -179,15 +203,26 @@ EXPORT_SYMBOL(suspend_block);
  */
 void suspend_unblock(struct suspend_blocker *blocker)
 {
-	WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));
+	unsigned long irqflags;
+
+	if (WARN_ON(!(blocker->flags & SB_INITIALIZED)))
+		return;
+
+	spin_lock_irqsave(&list_lock, irqflags);
 
 	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
 		pr_info("suspend_unblock: %s\n", blocker->name);
+	list_del(&blocker->link);
+	list_add(&blocker->link, &inactive_blockers);
 
-	if (atomic_cmpxchg(&blocker->flags, SB_INITIALIZED | SB_ACTIVE,
-	    SB_INITIALIZED) == (SB_INITIALIZED | SB_ACTIVE))
-		if (atomic_dec_and_test(&suspend_block_count))
-			queue_work(suspend_work_queue, &suspend_work);
+	if ((blocker->flags & SB_ACTIVE) && list_empty(&active_blockers))
+		queue_work(suspend_work_queue, &suspend_work);
+	blocker->flags &= ~(SB_ACTIVE);
+	if (blocker == &main_suspend_blocker) {
+		if (debug_mask & DEBUG_SUSPEND)
+			print_active_blockers_locked();
+	}
+	spin_unlock_irqrestore(&list_lock, irqflags);
 }
 EXPORT_SYMBOL(suspend_unblock);
 
@@ -199,9 +234,9 @@ EXPORT_SYMBOL(suspend_unblock);
  */
 bool suspend_blocker_is_active(struct suspend_blocker *blocker)
 {
-	WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));
+	WARN_ON(!(blocker->flags & SB_INITIALIZED));
 
-	return !!(atomic_read(&blocker->flags) & SB_ACTIVE);
+	return !!(blocker->flags & SB_ACTIVE);
 }
 EXPORT_SYMBOL(suspend_blocker_is_active);
 
-- 
1.6.1

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[PATCH 6/9] PM: suspend_block: Add debugfs file

[Arve Hjønnevåg]

Report active and inactive suspend blockers in
/sys/kernel/debug/suspend_blockers.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 kernel/power/suspend_blocker.c |   45 ++++++++++++++++++++++++++++++++++++++-
 1 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/kernel/power/suspend_blocker.c b/kernel/power/suspend_blocker.c
index 94832ca..da7248a 100644
--- a/kernel/power/suspend_blocker.c
+++ b/kernel/power/suspend_blocker.c
@@ -18,6 +18,7 @@
 #include <linux/suspend.h>
 #include <linux/suspend_blocker.h>
 #include <linux/sysdev.h>
+#include <linux/debugfs.h>
 #include "power.h"
 
 enum {
@@ -42,6 +43,7 @@ struct workqueue_struct *suspend_work_queue;
 struct suspend_blocker main_suspend_blocker;
 static suspend_state_t requested_suspend_state = PM_SUSPEND_MEM;
 static bool enable_suspend_blockers;
+static struct dentry *suspend_blocker_stats_dentry;
 
 #define pr_info_time(fmt, args...) \
 	do { \
@@ -55,6 +57,21 @@ static bool enable_suspend_blockers;
 			tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec); \
 	} while (0);
 
+static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
+{
+	unsigned long irqflags;
+	struct suspend_blocker *blocker;
+
+	seq_puts(m, "name\tactive\n");
+	spin_lock_irqsave(&list_lock, irqflags);
+	list_for_each_entry(blocker, &inactive_blockers, link)
+		seq_printf(m, "\"%s\"\t0\n", blocker->name);
+	list_for_each_entry(blocker, &active_blockers, link)
+		seq_printf(m, "\"%s\"\t1\n", blocker->name);
+	spin_unlock_irqrestore(&list_lock, irqflags);
+	return 0;
+}
+
 static void print_active_blockers_locked(void)
 {
 	struct suspend_blocker *blocker;
@@ -128,8 +145,8 @@ static struct sys_device suspend_block_sysdev = {
 /**
  * suspend_blocker_init() - Initialize a suspend blocker
  * @blocker:	The suspend blocker to initialize.
- * @name:	The name of the suspend blocker to show in debug messages.
- *
+ * @name:	The name of the suspend blocker to show in debug messages and
+ *		/sys/kernel/debug/suspend_blockers.
  * The suspend blocker struct and name must not be freed before calling
  * suspend_blocker_destroy.
  */
@@ -257,6 +274,19 @@ void request_suspend_state(suspend_state_t state)
 	spin_unlock_irqrestore(&state_lock, irqflags);
 }
 
+static int suspend_blocker_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, suspend_blocker_stats_show, NULL);
+}
+
+static const struct file_operations suspend_blocker_stats_fops = {
+	.owner = THIS_MODULE,
+	.open = suspend_blocker_stats_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
 static int __init suspend_block_init(void)
 {
 	int ret;
@@ -292,8 +322,18 @@ err_sysdev_class_register:
 	return ret;
 }
 
+static int __init suspend_block_postcore_init(void)
+{
+	if (!suspend_work_queue)
+		return 0;
+	suspend_blocker_stats_dentry = debugfs_create_file("suspend_blockers",
+			S_IRUGO, NULL, NULL, &suspend_blocker_stats_fops);
+	return 0;
+}
+
 static void  __exit suspend_block_exit(void)
 {
+	debugfs_remove(suspend_blocker_stats_dentry);
 	destroy_workqueue(suspend_work_queue);
 	sysdev_unregister(&suspend_block_sysdev);
 	sysdev_class_unregister(&suspend_block_sysclass);
@@ -301,4 +341,5 @@ static void  __exit suspend_block_exit(void)
 }
 
 core_initcall(suspend_block_init);
+postcore_initcall(suspend_block_postcore_init);
 module_exit(suspend_block_exit);
-- 
1.6.1

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https://lists.linux-foundation.org/mailman/listinfo/linux-pm

[PATCH 7/9] PM: suspend_block: Add suspend_blocker stats

[Arve Hjønnevåg]

Report suspend block stats in /sys/kernel/debug/suspend_blockers.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 include/linux/suspend_blocker.h |   21 +++++-
 kernel/power/Kconfig            |    7 ++
 kernel/power/suspend_blocker.c  |  176 ++++++++++++++++++++++++++++++++++++++-
 3 files changed, 201 insertions(+), 3 deletions(-)

diff --git a/include/linux/suspend_blocker.h b/include/linux/suspend_blocker.h
index 1faa433..3bb8a6a 100755
--- a/include/linux/suspend_blocker.h
+++ b/include/linux/suspend_blocker.h
@@ -17,12 +17,21 @@
 #define _LINUX_SUSPEND_BLOCKER_H
 
 #include <linux/list.h>
+#include <linux/ktime.h>
 
 /**
  * struct suspend_blocker - the basic suspend_blocker structure
  * @link:	List entry for active or inactive list.
- * @flags:	Tracks initialized and active state.
+ * @flags:	Tracks initialized, active and stats state.
  * @name:	Name used for debugging.
+ * @count:	Number of times this blocker has been deacivated
+ * @wakeup_count: Number of times this blocker was the first to block suspend
+ *		after resume.
+ * @total_time:	Total time this suspend blocker has prevented suspend.
+ * @prevent_suspend_time: Time this suspend blocker has prevented suspend while
+ *		user-space requested suspend.
+ * @max_time:	Max time this suspend blocker has been continuously active
+ * @last_time:	Monotonic clock when the active state last changed.
  *
  * When a suspend_blocker is active it prevents the system from entering
  * suspend.
@@ -35,6 +44,16 @@ struct suspend_blocker {
 	struct list_head    link;
 	int                 flags;
 	const char         *name;
+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+	struct {
+		int             count;
+		int             wakeup_count;
+		ktime_t         total_time;
+		ktime_t         prevent_suspend_time;
+		ktime_t         max_time;
+		ktime_t         last_time;
+	} stat;
+#endif
 #endif
 };
 
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 84b423f..44bfaeb 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -126,6 +126,13 @@ config SUSPEND_BLOCKERS
 	  through /sys/power/request_state, the requested sleep state will be
 	  entered when no suspend blockers are active.
 
+config SUSPEND_BLOCKER_STATS
+	bool "Suspend block stats"
+	depends on SUSPEND_BLOCKERS
+	default y
+	---help---
+	  Report suspend block stats in /sys/kernel/debug/suspend_blockers
+
 config USER_SUSPEND_BLOCKERS
 	bool "Userspace suspend blockers"
 	depends on SUSPEND_BLOCKERS
diff --git a/kernel/power/suspend_blocker.c b/kernel/power/suspend_blocker.c
index da7248a..ab4d8d5 100644
--- a/kernel/power/suspend_blocker.c
+++ b/kernel/power/suspend_blocker.c
@@ -33,6 +33,7 @@ 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)
 
 static DEFINE_SPINLOCK(list_lock);
 static DEFINE_SPINLOCK(state_lock);
@@ -43,6 +44,7 @@ struct workqueue_struct *suspend_work_queue;
 struct suspend_blocker main_suspend_blocker;
 static suspend_state_t requested_suspend_state = PM_SUSPEND_MEM;
 static bool enable_suspend_blockers;
+static struct suspend_blocker unknown_wakeup;
 static struct dentry *suspend_blocker_stats_dentry;
 
 #define pr_info_time(fmt, args...) \
@@ -57,6 +59,148 @@ static struct dentry *suspend_blocker_stats_dentry;
 			tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec); \
 	} while (0);
 
+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+static struct suspend_blocker deleted_suspend_blockers;
+static ktime_t last_sleep_time_update;
+static bool wait_for_wakeup;
+
+static int print_blocker_stat(struct seq_file *m,
+			      struct suspend_blocker *blocker)
+{
+	int lock_count = blocker->stat.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();
+		add_time = ktime_sub(now, blocker->stat.last_time);
+		lock_count++;
+		active_time = add_time;
+		total_time = ktime_add(total_time, add_time);
+		if (blocker->flags & SB_PREVENTING_SUSPEND)
+			prevent_suspend_time = ktime_add(prevent_suspend_time,
+					ktime_sub(now, last_sleep_time_update));
+		if (add_time.tv64 > max_time.tv64)
+			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),
+		       ktime_to_ns(prevent_suspend_time), ktime_to_ns(max_time),
+		       ktime_to_ns(blocker->stat.last_time));
+}
+
+
+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"
+		 "\ttotal_time\tsleep_time\tmax_time\tlast_change\n");
+	spin_lock_irqsave(&list_lock, irqflags);
+	list_for_each_entry(blocker, &inactive_blockers, link)
+		print_blocker_stat(m, blocker);
+	list_for_each_entry(blocker, &active_blockers, link)
+		print_blocker_stat(m, blocker);
+	spin_unlock_irqrestore(&list_lock, irqflags);
+	return 0;
+}
+
+static void suspend_blocker_stat_init_locked(struct suspend_blocker *blocker)
+{
+	blocker->stat.count = 0;
+	blocker->stat.wakeup_count = 0;
+	blocker->stat.total_time = ktime_set(0, 0);
+	blocker->stat.prevent_suspend_time = ktime_set(0, 0);
+	blocker->stat.max_time = ktime_set(0, 0);
+	blocker->stat.last_time = ktime_set(0, 0);
+}
+
+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.total_time = ktime_add(
+		deleted_suspend_blockers.stat.total_time, bl->stat.total_time);
+	deleted_suspend_blockers.stat.prevent_suspend_time = ktime_add(
+		deleted_suspend_blockers.stat.prevent_suspend_time,
+		bl->stat.prevent_suspend_time);
+	deleted_suspend_blockers.stat.max_time = ktime_add(
+		deleted_suspend_blockers.stat.max_time, bl->stat.max_time);
+}
+
+static void suspend_unblock_stat_locked(struct suspend_blocker *blocker)
+{
+	ktime_t duration;
+	ktime_t now;
+	if (!(blocker->flags & SB_ACTIVE))
+		return;
+	now = ktime_get();
+	blocker->stat.count++;
+	duration = ktime_sub(now, blocker->stat.last_time);
+	blocker->stat.total_time =
+		ktime_add(blocker->stat.total_time, duration);
+	if (ktime_to_ns(duration) > ktime_to_ns(blocker->stat.max_time))
+		blocker->stat.max_time = duration;
+	blocker->stat.last_time = ktime_get();
+	if (blocker->flags & SB_PREVENTING_SUSPEND) {
+		duration = ktime_sub(now, last_sleep_time_update);
+		blocker->stat.prevent_suspend_time = ktime_add(
+			blocker->stat.prevent_suspend_time, duration);
+		blocker->flags &= ~SB_PREVENTING_SUSPEND;
+	}
+}
+
+static void suspend_block_stat_locked(struct suspend_blocker *blocker)
+{
+	if (wait_for_wakeup) {
+		if (debug_mask & DEBUG_WAKEUP)
+			pr_info("wakeup suspend blocker: %s\n", blocker->name);
+		wait_for_wakeup = false;
+		blocker->stat.wakeup_count++;
+	}
+	if (!(blocker->flags & SB_ACTIVE))
+		blocker->stat.last_time = ktime_get();
+}
+
+static void update_sleep_wait_stats_locked(bool done)
+{
+	struct suspend_blocker *blocker;
+	ktime_t now, elapsed, add;
+
+	now = ktime_get();
+	elapsed = ktime_sub(now, last_sleep_time_update);
+	list_for_each_entry(blocker, &active_blockers, link) {
+		if (blocker->flags & SB_PREVENTING_SUSPEND) {
+			add = elapsed;
+			blocker->stat.prevent_suspend_time = ktime_add(
+				blocker->stat.prevent_suspend_time, add);
+		}
+		if (done)
+			blocker->flags &= ~SB_PREVENTING_SUSPEND;
+		else
+			blocker->flags |= SB_PREVENTING_SUSPEND;
+	}
+	last_sleep_time_update = now;
+}
+
+#else
+
+static inline void suspend_blocker_stat_init_locked(
+					struct suspend_blocker *blocker) {}
+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 update_sleep_wait_stats_locked(bool done) {}
+
 static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
 {
 	unsigned long irqflags;
@@ -72,6 +216,8 @@ static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
 	return 0;
 }
 
+#endif
+
 static void print_active_blockers_locked(void)
 {
 	struct suspend_blocker *blocker;
@@ -103,7 +249,6 @@ static void suspend_worker(struct work_struct *work)
 
 	enable_suspend_blockers = true;
 
-retry:
 	if (suspend_is_blocked()) {
 		if (debug_mask & DEBUG_SUSPEND)
 			pr_info("suspend: abort suspend\n");
@@ -119,7 +264,8 @@ retry:
 	if (current_event_num == entry_event_num) {
 		if (debug_mask & DEBUG_SUSPEND)
 			pr_info("suspend: pm_suspend returned with no event\n");
-		goto retry;
+		suspend_block(&unknown_wakeup);
+		suspend_unblock(&unknown_wakeup);
 	}
 abort:
 	enable_suspend_blockers = false;
@@ -129,6 +275,9 @@ static DECLARE_WORK(suspend_work, suspend_worker);
 static int suspend_block_suspend(struct sys_device *dev, pm_message_t state)
 {
 	int ret = suspend_is_blocked() ? -EAGAIN : 0;
+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+	wait_for_wakeup = true;
+#endif
 	if (debug_mask & DEBUG_SUSPEND)
 		pr_info("suspend_block_suspend return %d\n", ret);
 	return ret;
@@ -164,6 +313,7 @@ void suspend_blocker_init(struct suspend_blocker *blocker, const char *name)
 	INIT_LIST_HEAD(&blocker->link);
 
 	spin_lock_irqsave(&list_lock, irqflags);
+	suspend_blocker_stat_init_locked(blocker);
 	list_add(&blocker->link, &inactive_blockers);
 	spin_unlock_irqrestore(&list_lock, irqflags);
 }
@@ -181,6 +331,7 @@ void suspend_blocker_destroy(struct suspend_blocker *blocker)
 	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
 		pr_info("suspend_blocker_destroy name=%s\n", blocker->name);
 	spin_lock_irqsave(&list_lock, irqflags);
+	suspend_blocker_stat_destroy_locked(blocker);
 	blocker->flags &= ~SB_INITIALIZED;
 	list_del(&blocker->link);
 	if ((blocker->flags & SB_ACTIVE) && list_empty(&active_blockers))
@@ -201,6 +352,7 @@ void suspend_block(struct suspend_blocker *blocker)
 		return;
 
 	spin_lock_irqsave(&list_lock, irqflags);
+	suspend_block_stat_locked(blocker);
 	blocker->flags |= SB_ACTIVE;
 	list_del(&blocker->link);
 	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
@@ -208,6 +360,10 @@ void suspend_block(struct suspend_blocker *blocker)
 	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);
 	spin_unlock_irqrestore(&list_lock, irqflags);
 }
 EXPORT_SYMBOL(suspend_block);
@@ -227,6 +383,8 @@ void suspend_unblock(struct suspend_blocker *blocker)
 
 	spin_lock_irqsave(&list_lock, irqflags);
 
+	suspend_unblock_stat_locked(blocker);
+
 	if (debug_mask & DEBUG_SUSPEND_BLOCKER)
 		pr_info("suspend_unblock: %s\n", blocker->name);
 	list_del(&blocker->link);
@@ -238,6 +396,7 @@ void suspend_unblock(struct suspend_blocker *blocker)
 	if (blocker == &main_suspend_blocker) {
 		if (debug_mask & DEBUG_SUSPEND)
 			print_active_blockers_locked();
+		update_sleep_wait_stats_locked(false);
 	}
 	spin_unlock_irqrestore(&list_lock, irqflags);
 }
@@ -291,8 +450,13 @@ static int __init suspend_block_init(void)
 {
 	int ret;
 
+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+	suspend_blocker_init(&deleted_suspend_blockers,
+				"deleted_suspend_blockers");
+#endif
 	suspend_blocker_init(&main_suspend_blocker, "main");
 	suspend_block(&main_suspend_blocker);
+	suspend_blocker_init(&unknown_wakeup, "unknown_wakeups");
 
 	ret = sysdev_class_register(&suspend_block_sysclass);
 	if (ret) {
@@ -318,7 +482,11 @@ err_suspend_work_queue:
 err_sysdev_register:
 	sysdev_class_unregister(&suspend_block_sysclass);
 err_sysdev_class_register:
+	suspend_blocker_destroy(&unknown_wakeup);
 	suspend_blocker_destroy(&main_suspend_blocker);
+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+	suspend_blocker_destroy(&deleted_suspend_blockers);
+#endif
 	return ret;
 }
 
@@ -337,7 +505,11 @@ static void  __exit suspend_block_exit(void)
 	destroy_workqueue(suspend_work_queue);
 	sysdev_unregister(&suspend_block_sysdev);
 	sysdev_class_unregister(&suspend_block_sysclass);
+	suspend_blocker_destroy(&unknown_wakeup);
 	suspend_blocker_destroy(&main_suspend_blocker);
+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+	suspend_blocker_destroy(&deleted_suspend_blockers);
+#endif
 }
 
 core_initcall(suspend_block_init);
-- 
1.6.1

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

[Arve Hjønnevåg]

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

[Arve Hjønnevåg]

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

[Michael Trimarchi]

Hi,

Arve Hjønnevåg wrote:

[snip]
> Add suspend_block_timeout to block suspend for a limited time.
>
> Signed-off-by: Arve Hjønnevåg <arve@android.com>
> ---
> +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)
>   
So the max_timeout can be negative?
> +
Michael
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Re: [PATCH 8/9] PM: suspend_block: Add timeout support.

[Michael Trimarchi]

Michael Trimarchi wrote:
> Hi,
>
> Arve Hjønnevåg wrote:
>
> [snip]
>   
>> Add suspend_block_timeout to block suspend for a limited time.
>>
>> Signed-off-by: Arve Hjønnevåg <arve@android.com>
>> ---
>> +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)
>>   
>>     
> So the max_timeout can be negative?
>   

	update_sleep_wait_stats_locked(false);
+	update_suspend(blocker, has_timeout ?
+			max_suspend_blocker_timeout_locked() : -1);
 	spin_unlock_irqrestore(&list_lock, irqflags);

Ok sorry maybe in this call... I write to fast the email :(

>> +
>>     
> Michael
> _______________________________________________
> linux-pm mailing list
> linux-pm@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/linux-pm

_______________________________________________
linux-pm mailing list
linux-pm@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/linux-pm

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

2010/4/27 Rafael J. Wysocki <rjw@sisk.pl>:
> On Tuesday 27 April 2010, Alan Stern wrote:
>> On Mon, 26 Apr 2010, Arve Hjønnevåg wrote:
>>
>> > > If you insist on using ioctl for init, you should use the standard
>> > > convention for passing variable-length data.  The userspace program
>> > > sets up a fixed-size buffer containing a pointer to the name and the
>> > > name's length, and it passes the buffer's address as the ioctl
>> > > argument.
>> >
>> > Are you sure that is the standard? I searched for ioctls with NAME in
>> > their name and only found one that passed the name that way. The rest
>> > used fixed length string buffers, or passed the buffersize to _IOC
>> > like I do. For instance, input.h has ioctls to read string and
>> > bitmasks where user space specify the buffer size as an argument to
>> > the ioctl macro. These pass data from the kernel to user space, but I
>> > don't passing a string length is any worse than passing a buffer size.
>>
>> You're right.  Okay, I withdraw my objection.
>
> In the meantime, though, I thought that the suspend blocker might be created
> by _open() if we found a way to automatically choose a name for it.  That'd be
> kind of logical, since it's later destroyed by _release().
>
> So, what about using the name of the process that opened the special device
> file (or that name with'0' appended, or generally with a number appended) as
> the suspend blocker name?
>

I prefer to let user space choose the name since we use more than one
suspend blocker in the same process.

-- 
Arve Hjønnevåg

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Rafael J. Wysocki]

On Tuesday 27 April 2010, Alan Stern wrote:
> On Mon, 26 Apr 2010, Arve Hjønnevåg wrote:
> 
> > > If you insist on using ioctl for init, you should use the standard
> > > convention for passing variable-length data.  The userspace program
> > > sets up a fixed-size buffer containing a pointer to the name and the
> > > name's length, and it passes the buffer's address as the ioctl
> > > argument.
> > 
> > Are you sure that is the standard? I searched for ioctls with NAME in
> > their name and only found one that passed the name that way. The rest
> > used fixed length string buffers, or passed the buffersize to _IOC
> > like I do. For instance, input.h has ioctls to read string and
> > bitmasks where user space specify the buffer size as an argument to
> > the ioctl macro. These pass data from the kernel to user space, but I
> > don't passing a string length is any worse than passing a buffer size.
> 
> You're right.  Okay, I withdraw my objection.

In the meantime, though, I thought that the suspend blocker might be created
by _open() if we found a way to automatically choose a name for it.  That'd be
kind of logical, since it's later destroyed by _release().

So, what about using the name of the process that opened the special device
file (or that name with'0' appended, or generally with a number appended) as
the suspend blocker name?

Rafael

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Alan Stern]

On Mon, 26 Apr 2010, Arve Hjønnevåg wrote:

> > If you insist on using ioctl for init, you should use the standard
> > convention for passing variable-length data.  The userspace program
> > sets up a fixed-size buffer containing a pointer to the name and the
> > name's length, and it passes the buffer's address as the ioctl
> > argument.
> 
> Are you sure that is the standard? I searched for ioctls with NAME in
> their name and only found one that passed the name that way. The rest
> used fixed length string buffers, or passed the buffersize to _IOC
> like I do. For instance, input.h has ioctls to read string and
> bitmasks where user space specify the buffer size as an argument to
> the ioctl macro. These pass data from the kernel to user space, but I
> don't passing a string length is any worse than passing a buffer size.

You're right.  Okay, I withdraw my objection.

Alan Stern

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

2010/4/26 Alan Stern <stern@rowland.harvard.edu>:
> On Sun, 25 Apr 2010, Arve Hjønnevåg wrote:
>
>> >> > >> > +User-space API
>> >> > >> > +==============
>> >> > >> > +
>> >> > >> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
>> >> > >> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
>> >> > >> > +then call:
>> >> > >> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
>> >> > >>
>> >> > >>
>> >> > >> This seems like very wrong idea -- it uses different ioctl number for
>> >> > >> each length AFAICT.
>> >> > >
>> >> > > How about specifying the name by an ordinary write() call instead of
>> >> > > by an ioctl()?
>> >> > >
>> >> >
>> >> > I prefer using ioctls. We have three operations at the moment. Init,
>> >> > block and unblock. If we do init with write but block and unblock
>> >> > using ioctls, it would be pretty strange. Specifying a command and
>> >>
>> >> Why would it be "strange"?
>> >
>> > Why indeed?  Using write() is the natural way to pass a data buffer
>> > into the kernel, especially a variable-length buffer.
>> >
>> > Mixing ioctl() and write() might seem strange at first, but it has
>> > plenty of precedent.  Consider adjusting the settings for a serial
>> > port, for example.
>> >
>> That sound like to opposite situation to me. It uses ioctls for setup
>> and read/write access the data stream.
>
> Or you could say that it uses ioctls to send commands and read/write to
> pass data.  That's pretty much what you would be doing.
>
> Let's put it another way: You find it excessively strange to do init
> using write and to send commands via ioctl, but you don't find it
> strange to abuse the ioctl number code for passing the string length?
> The old saying about motes and beams applies here...
>
> If you insist on using ioctl for init, you should use the standard
> convention for passing variable-length data.  The userspace program
> sets up a fixed-size buffer containing a pointer to the name and the
> name's length, and it passes the buffer's address as the ioctl
> argument.

Are you sure that is the standard? I searched for ioctls with NAME in
their name and only found one that passed the name that way. The rest
used fixed length string buffers, or passed the buffersize to _IOC
like I do. For instance, input.h has ioctls to read string and
bitmasks where user space specify the buffer size as an argument to
the ioctl macro. These pass data from the kernel to user space, but I
don't passing a string length is any worse than passing a buffer size.

-- 
Arve Hjønnevåg

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Alan Stern]

On Sun, 25 Apr 2010, Arve Hjønnevåg wrote:

> >> > >> > +User-space API
> >> > >> > +==============
> >> > >> > +
> >> > >> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
> >> > >> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> >> > >> > +then call:
> >> > >> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
> >> > >>
> >> > >>
> >> > >> This seems like very wrong idea -- it uses different ioctl number for
> >> > >> each length AFAICT.
> >> > >
> >> > > How about specifying the name by an ordinary write() call instead of
> >> > > by an ioctl()?
> >> > >
> >> >
> >> > I prefer using ioctls. We have three operations at the moment. Init,
> >> > block and unblock. If we do init with write but block and unblock
> >> > using ioctls, it would be pretty strange. Specifying a command and
> >>
> >> Why would it be "strange"?
> >
> > Why indeed?  Using write() is the natural way to pass a data buffer
> > into the kernel, especially a variable-length buffer.
> >
> > Mixing ioctl() and write() might seem strange at first, but it has
> > plenty of precedent.  Consider adjusting the settings for a serial
> > port, for example.
> >
> That sound like to opposite situation to me. It uses ioctls for setup
> and read/write access the data stream.

Or you could say that it uses ioctls to send commands and read/write to 
pass data.  That's pretty much what you would be doing.

Let's put it another way: You find it excessively strange to do init
using write and to send commands via ioctl, but you don't find it
strange to abuse the ioctl number code for passing the string length?  
The old saying about motes and beams applies here...

If you insist on using ioctl for init, you should use the standard
convention for passing variable-length data.  The userspace program
sets up a fixed-size buffer containing a pointer to the name and the
name's length, and it passes the buffer's address as the ioctl
argument.

Alan Stern

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

On Sat, Apr 24, 2010 at 7:44 AM, Alan Stern <stern@rowland.harvard.edu> wrote:
> On Sat, 24 Apr 2010, Pavel Machek wrote:
>
>> On Fri 2010-04-23 20:20:47, Arve Hj?nnev?g wrote:
>> > On Fri, Apr 23, 2010 at 9:43 AM, Alan Stern <stern@rowland.harvard.edu> wrote:
>> > > On Fri, 23 Apr 2010, Pavel Machek wrote:
>> > >
>> > >> Hi!
>> > >>
>> > >> > 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 Hj??nnev??g <arve@android.com>
>> > >>
>> > >> > --- a/Documentation/power/suspend-blockers.txt
>> > >> > +++ b/Documentation/power/suspend-blockers.txt
>> > >> > @@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
>> > >> >  else
>> > >> >     suspend_block(&state->suspend_blocker);
>> > >> >
>> > >> > +User-space API
>> > >> > +==============
>> > >> > +
>> > >> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
>> > >> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
>> > >> > +then call:
>> > >> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
>> > >>
>> > >>
>> > >> This seems like very wrong idea -- it uses different ioctl number for
>> > >> each length AFAICT.
>> > >
>> > > How about specifying the name by an ordinary write() call instead of
>> > > by an ioctl()?
>> > >
>> >
>> > I prefer using ioctls. We have three operations at the moment. Init,
>> > block and unblock. If we do init with write but block and unblock
>> > using ioctls, it would be pretty strange. Specifying a command and
>>
>> Why would it be "strange"?
>
> Why indeed?  Using write() is the natural way to pass a data buffer
> into the kernel, especially a variable-length buffer.
>
> Mixing ioctl() and write() might seem strange at first, but it has
> plenty of precedent.  Consider adjusting the settings for a serial
> port, for example.
>
That sound like to opposite situation to me. It uses ioctls for setup
and read/write access the data stream.

>> > argument in a string to write is more complicated to parse than using
>> > ioctls.
>>
>> More complicated to parse?
>
> It shouldn't be -- especially if you assume that the init action must
> always come first.  The first write would contain the suspend blocker's
> name; all following writes would have to be either "on" or "off".
> That's not hard to parse.
>

Why should I have to parse a string at all? We already have a control
interface, ioctl, where user space can pass a command with data. If we
later want to add other commands we can easily add them without
breaking existing command. With your interface, where the first write
is a name, adding more initialization data later becomes harder. I
also don't like that wring the same string twice has a different
meaning the second time. With the ioctl interface, you forget to
initialize the suspend blocker, it block and unblock operations will
fail. With your interface you create a suspend blocker call "on" or
"off".

-- 
Arve Hjønnevåg

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Alan Stern]

On Sat, 24 Apr 2010, Pavel Machek wrote:

> On Fri 2010-04-23 20:20:47, Arve Hj?nnev?g wrote:
> > On Fri, Apr 23, 2010 at 9:43 AM, Alan Stern <stern@rowland.harvard.edu> wrote:
> > > On Fri, 23 Apr 2010, Pavel Machek wrote:
> > >
> > >> Hi!
> > >>
> > >> > 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 Hj??nnev??g <arve@android.com>
> > >>
> > >> > --- a/Documentation/power/suspend-blockers.txt
> > >> > +++ b/Documentation/power/suspend-blockers.txt
> > >> > @@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
> > >> >  else
> > >> >     suspend_block(&state->suspend_blocker);
> > >> >
> > >> > +User-space API
> > >> > +==============
> > >> > +
> > >> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
> > >> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> > >> > +then call:
> > >> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
> > >>
> > >>
> > >> This seems like very wrong idea -- it uses different ioctl number for
> > >> each length AFAICT.
> > >
> > > How about specifying the name by an ordinary write() call instead of
> > > by an ioctl()?
> > >
> > 
> > I prefer using ioctls. We have three operations at the moment. Init,
> > block and unblock. If we do init with write but block and unblock
> > using ioctls, it would be pretty strange. Specifying a command and
> 
> Why would it be "strange"?

Why indeed?  Using write() is the natural way to pass a data buffer
into the kernel, especially a variable-length buffer.

Mixing ioctl() and write() might seem strange at first, but it has
plenty of precedent.  Consider adjusting the settings for a serial
port, for example.

> > argument in a string to write is more complicated to parse than using
> > ioctls.
> 
> More complicated to parse?

It shouldn't be -- especially if you assume that the init action must
always come first.  The first write would contain the suspend blocker's
name; all following writes would have to be either "on" or "off".  
That's not hard to parse.

Alan Stern

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

On Fri 2010-04-23 20:20:47, Arve Hj?nnev?g wrote:
> On Fri, Apr 23, 2010 at 9:43 AM, Alan Stern <stern@rowland.harvard.edu> wrote:
> > On Fri, 23 Apr 2010, Pavel Machek wrote:
> >
> >> Hi!
> >>
> >> > 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 Hj??nnev??g <arve@android.com>
> >>
> >> > --- a/Documentation/power/suspend-blockers.txt
> >> > +++ b/Documentation/power/suspend-blockers.txt
> >> > @@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
> >> >  else
> >> >     suspend_block(&state->suspend_blocker);
> >> >
> >> > +User-space API
> >> > +==============
> >> > +
> >> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
> >> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> >> > +then call:
> >> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
> >>
> >>
> >> This seems like very wrong idea -- it uses different ioctl number for
> >> each length AFAICT.
> >
> > How about specifying the name by an ordinary write() call instead of
> > by an ioctl()?
> >
> 
> I prefer using ioctls. We have three operations at the moment. Init,
> block and unblock. If we do init with write but block and unblock
> using ioctls, it would be pretty strange. Specifying a command and

Why would it be "strange"?

> argument in a string to write is more complicated to parse than using
> ioctls.

More complicated to parse?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

On Fri 2010-04-23 21:53:34, tytso@mit.edu wrote:
> On Fri, Apr 23, 2010 at 10:43:49AM +0200, Pavel Machek wrote:
> > > +To create a suspend_blocker from user-space, open the suspend_blocker device:
> > > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> > > +then call:
> > > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
> > 
> > 
> > This seems like very wrong idea -- it uses different ioctl number for
> > each length AFAICT.
> 
> Yep, and there's nothing wrong with that IMHO.  It's a clever use of
> the _IOC encoding scheme.

I'm not sure if "clever" is right word. So what if strlen is in 2GB
range, will macros still work correctly?

Will it be easy for strace to display such ioctls?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

On Fri 2010-04-23 21:53:34, tytso@mit.edu wrote:
> On Fri, Apr 23, 2010 at 10:43:49AM +0200, Pavel Machek wrote:
> > > +To create a suspend_blocker from user-space, open the suspend_blocker device:
> > > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> > > +then call:
> > > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
> > 
> > 
> > This seems like very wrong idea -- it uses different ioctl number for
> > each length AFAICT.
> 
> Yep, and there's nothing wrong with that IMHO.  It's a clever use of
> the _IOC encoding scheme.

I'm not sure if "clever" is right word. So what if strlen is in 2GB
range, will macros still work correctly?

Will it be easy for strace to display such ioctls?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

On Fri, Apr 23, 2010 at 9:43 AM, Alan Stern <stern@rowland.harvard.edu> wrote:
> On Fri, 23 Apr 2010, Pavel Machek wrote:
>
>> Hi!
>>
>> > 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 Hj??nnev??g <arve@android.com>
>>
>> > --- a/Documentation/power/suspend-blockers.txt
>> > +++ b/Documentation/power/suspend-blockers.txt
>> > @@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
>> >  else
>> >     suspend_block(&state->suspend_blocker);
>> >
>> > +User-space API
>> > +==============
>> > +
>> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
>> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
>> > +then call:
>> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
>>
>>
>> This seems like very wrong idea -- it uses different ioctl number for
>> each length AFAICT.
>
> How about specifying the name by an ordinary write() call instead of
> by an ioctl()?
>

I prefer using ioctls. We have three operations at the moment. Init,
block and unblock. If we do init with write but block and unblock
using ioctls, it would be pretty strange. Specifying a command and
argument in a string to write is more complicated to parse than using
ioctls. Or did you have something else in mind?

-- 
Arve Hjønnevåg

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[tytso]

On Fri, Apr 23, 2010 at 10:43:49AM +0200, Pavel Machek wrote:
> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> > +then call:
> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
> 
> 
> This seems like very wrong idea -- it uses different ioctl number for
> each length AFAICT.

Yep, and there's nothing wrong with that IMHO.  It's a clever use of
the _IOC encoding scheme.

						- Ted

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[tytso]

On Fri, Apr 23, 2010 at 10:43:49AM +0200, Pavel Machek wrote:
> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> > +then call:
> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
> 
> 
> This seems like very wrong idea -- it uses different ioctl number for
> each length AFAICT.

Yep, and there's nothing wrong with that IMHO.  It's a clever use of
the _IOC encoding scheme.

						- Ted

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Alan Stern]

On Fri, 23 Apr 2010, Pavel Machek wrote:

> Hi!
> 
> > 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 Hj??nnev??g <arve@android.com>
> 
> > --- a/Documentation/power/suspend-blockers.txt
> > +++ b/Documentation/power/suspend-blockers.txt
> > @@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
> >  else
> >  	suspend_block(&state->suspend_blocker);
> >  
> > +User-space API
> > +==============
> > +
> > +To create a suspend_blocker from user-space, open the suspend_blocker device:
> > +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> > +then call:
> > +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
> 
> 
> This seems like very wrong idea -- it uses different ioctl number for
> each length AFAICT.

How about specifying the name by an ordinary write() call instead of
by an ioctl()?

Alan Stern

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

Hi!

> 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 Hj??nnev??g <arve@android.com>

> --- a/Documentation/power/suspend-blockers.txt
> +++ b/Documentation/power/suspend-blockers.txt
> @@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
>  else
>  	suspend_block(&state->suspend_blocker);
>  
> +User-space API
> +==============
> +
> +To create a suspend_blocker from user-space, open the suspend_blocker device:
> +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> +then call:
> +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);


This seems like very wrong idea -- it uses different ioctl number for
each length AFAICT.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

Hi!

> 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 Hj??nnev??g <arve@android.com>

> --- a/Documentation/power/suspend-blockers.txt
> +++ b/Documentation/power/suspend-blockers.txt
> @@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
>  else
>  	suspend_block(&state->suspend_blocker);
>  
> +User-space API
> +==============
> +
> +To create a suspend_blocker from user-space, open the suspend_blocker device:
> +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> +then call:
> +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);


This seems like very wrong idea -- it uses different ioctl number for
each length AFAICT.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Greg KH]

On Thu, Apr 22, 2010 at 07:25:22PM -0700, Matt Helsley wrote:
> Should the kernel reject empty strings or strings composed only of
> "non-printing" characters?

The kernel doesn't care, if you want to use non-printing characters, who
is it to complain?  :)

thanks,

greg k-h

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

2010/4/22 Matt Helsley <matthltc@us.ibm.com>:
...
> On Thu, Apr 22, 2010 at 06:08:51PM -0700, Arve Hjønnevåg wrote:
>> +To create a suspend_blocker from user-space, open the suspend_blocker device:
>> +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
>> +then call:
>> +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
>
> Why not initialize the user suspend blocker struct by default and then
> allow each BLOCK to specify the name? Also, my guess is it's not
> really a name so much as a description of why we're blocking suspend,
> right?
>

There are stats tracked as long as the suspend blocker exists.
Specifying a new name every time you block suspend would make this
less useful.

> Should the kernel reject empty strings or strings composed only of
> "non-printing" characters?
>

Is there an existing function that check if a sting is "unsafe". If
so, I can add a call to this.

>> +
>> +To activate a suspend_blocker call:
>> +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK);
>> +
>> +To unblock call:
>> +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_UNBLOCK);
>
> lsof will show which tasks hold the device open but not which ones
> are blocking suspend. If merely keeping the device open corresponded to
> blocking suspend then this would be obvious and no ioctls would be
> necessary -- just write() the name/description.

We track more information about suspend blockers than this.

>
> Do you block/unblock often enough that frequent open/close of the device are
> a problem?

Yes.

...
>> +
>> +static DEFINE_MUTEX(ioctl_lock);
>
> nit: Usually locks protect data -- not functions.
>
> Couldn't this be part of the user_suspend_blocker struct? That would allow
> the description/name to change as described above.

It mainly protects the allocation of that struct, so no. Allocating a
separate struct in open would work, but does not seem worth it at the
moment.

>
>> +
>> +struct user_suspend_blocker {
>> +     struct suspend_blocker  blocker;
>> +     char                    name[0];
>> +};
>
> <snip>
>
> Cheers,
>        -Matt Helsley
>



-- 
Arve Hjønnevåg

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Matt Helsley]

On Thu, Apr 22, 2010 at 06:08:51PM -0700, Arve Hjønnevåg wrote:
> 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/power/suspend-blockers.txt |   17 ++++
>  include/linux/suspend_block_dev.h        |   25 ++++++
>  kernel/power/Kconfig                     |    9 ++
>  kernel/power/Makefile                    |    1 +
>  kernel/power/user_suspend_blocker.c      |  128 ++++++++++++++++++++++++++++++
>  5 files changed, 180 insertions(+), 0 deletions(-)
>  create mode 100644 include/linux/suspend_block_dev.h
>  create mode 100644 kernel/power/user_suspend_blocker.c
> 
> diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txt
> index 1c48514..877bd8c 100644
> --- a/Documentation/power/suspend-blockers.txt
> +++ b/Documentation/power/suspend-blockers.txt
> @@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
>  else
>  	suspend_block(&state->suspend_blocker);
>  
> +User-space API
> +==============
> +
> +To create a suspend_blocker from user-space, open the suspend_blocker device:
> +    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
> +then call:
> +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);

Why not initialize the user suspend blocker struct by default and then
allow each BLOCK to specify the name? Also, my guess is it's not
really a name so much as a description of why we're blocking suspend,
right?

Should the kernel reject empty strings or strings composed only of
"non-printing" characters?

> +
> +To activate a suspend_blocker call:
> +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK);
> +
> +To unblock call:
> +    ioctl(fd, SUSPEND_BLOCKER_IOCTL_UNBLOCK);

lsof will show which tasks hold the device open but not which ones
are blocking suspend. If merely keeping the device open corresponded to
blocking suspend then this would be obvious and no ioctls would be
necessary -- just write() the name/description.

Do you block/unblock often enough that frequent open/close of the device are
a problem? Or has this idea been considered and discarded for other reasons?

> +
> +To destroy the suspend_blocker, close the device:
> +    close(fd);
> +

<snip>

> diff --git a/kernel/power/user_suspend_blocker.c b/kernel/power/user_suspend_blocker.c
> new file mode 100644
> index 0000000..a9be6f4
> --- /dev/null
> +++ b/kernel/power/user_suspend_blocker.c
> @@ -0,0 +1,128 @@
> +/* kernel/power/user_suspend_block.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_blocker.h>
> +#include <linux/suspend_block_dev.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);

nit: Usually locks protect data -- not functions.

Couldn't this be part of the user_suspend_blocker struct? That would allow
the description/name to change as described above.

> +
> +struct user_suspend_blocker {
> +	struct suspend_blocker	blocker;
> +	char			name[0];
> +};

<snip>

Cheers,
	-Matt Helsley

[PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

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/power/suspend-blockers.txt |   17 ++++
 include/linux/suspend_block_dev.h        |   25 ++++++
 kernel/power/Kconfig                     |    9 ++
 kernel/power/Makefile                    |    1 +
 kernel/power/user_suspend_blocker.c      |  128 ++++++++++++++++++++++++++++++
 5 files changed, 180 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/suspend_block_dev.h
 create mode 100644 kernel/power/user_suspend_blocker.c

diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txt
index 1c48514..877bd8c 100644
--- a/Documentation/power/suspend-blockers.txt
+++ b/Documentation/power/suspend-blockers.txt
@@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
 else
 	suspend_block(&state->suspend_blocker);
 
+User-space API
+==============
+
+To create a suspend_blocker from user-space, open the suspend_blocker device:
+    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
+then call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
+
+To activate a suspend_blocker call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK);
+
+To unblock call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_UNBLOCK);
+
+To destroy the suspend_blocker, close the device:
+    close(fd);
+
diff --git a/include/linux/suspend_block_dev.h b/include/linux/suspend_block_dev.h
new file mode 100644
index 0000000..24bc5c7
--- /dev/null
+++ b/include/linux/suspend_block_dev.h
@@ -0,0 +1,25 @@
+/* include/linux/suspend_block_dev.h
+ *
+ * Copyright (C) 2009 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.
+ *
+ */
+
+#ifndef _LINUX_SUSPEND_BLOCK_DEV_H
+#define _LINUX_SUSPEND_BLOCK_DEV_H
+
+#include <linux/ioctl.h>
+
+#define SUSPEND_BLOCKER_IOCTL_INIT(len)		_IOC(_IOC_WRITE, 's', 0, len)
+#define SUSPEND_BLOCKER_IOCTL_BLOCK		_IO('s', 1)
+#define SUSPEND_BLOCKER_IOCTL_UNBLOCK		_IO('s', 2)
+
+#endif
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index f8fa246..1ac50ee 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -141,6 +141,15 @@ config SUSPEND_BLOCKERS
 	  state through /sys/power/state, the requested sleep state will be
 	  entered when no suspend blockers are active.
 
+config USER_SUSPEND_BLOCKERS
+	bool "Userspace suspend blockers"
+	depends on SUSPEND_BLOCKERS
+	default y
+	---help---
+	  User-space suspend block api. Creates a misc device with ioctls
+	  to create, block and unblock a suspend_blocker. The suspend_blocker
+	  will be deleted when the device is closed.
+
 config HIBERNATION_NVS
 	bool
 
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index f570801..80086c6 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_SUSPEND_BLOCKERS)	+= suspend_blocker.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..a9be6f4
--- /dev/null
+++ b/kernel/power/user_suspend_blocker.c
@@ -0,0 +1,128 @@
+/* kernel/power/user_suspend_block.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_blocker.h>
+#include <linux/suspend_block_dev.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);
+
+struct user_suspend_blocker {
+	struct suspend_blocker	blocker;
+	char			name[0];
+};
+
+static int create_user_suspend_blocker(struct file *file, void __user *name,
+				 size_t name_len)
+{
+	struct user_suspend_blocker *bl;
+	if (file->private_data)
+		return -EBUSY;
+	if (name_len > NAME_MAX)
+		return -ENAMETOOLONG;
+	bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
+	if (!bl)
+		return -ENOMEM;
+	if (copy_from_user(bl->name, name, name_len))
+		goto err_fault;
+	suspend_blocker_init(&bl->blocker, bl->name);
+	file->private_data = bl;
+	return 0;
+
+err_fault:
+	kfree(bl);
+	return -EFAULT;
+}
+
+static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
+				unsigned long _arg)
+{
+	void __user *arg = (void __user *)_arg;
+	struct user_suspend_blocker *bl;
+	long ret;
+
+	mutex_lock(&ioctl_lock);
+	if ((cmd & ~IOCSIZE_MASK) == SUSPEND_BLOCKER_IOCTL_INIT(0)) {
+		ret = create_user_suspend_blocker(file, arg, _IOC_SIZE(cmd));
+		goto done;
+	}
+	bl = file->private_data;
+	if (!bl) {
+		ret = -ENOENT;
+		goto done;
+	}
+	switch (cmd) {
+	case SUSPEND_BLOCKER_IOCTL_BLOCK:
+		suspend_block(&bl->blocker);
+		ret = 0;
+		break;
+	case SUSPEND_BLOCKER_IOCTL_UNBLOCK:
+		suspend_unblock(&bl->blocker);
+		ret = 0;
+		break;
+	default:
+		ret = -ENOTSUPP;
+	}
+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 *file)
+{
+	struct user_suspend_blocker *bl = file->private_data;
+	if (!bl)
+		return 0;
+	suspend_blocker_destroy(&bl->blocker);
+	kfree(bl);
+	return 0;
+}
+
+const struct file_operations user_suspend_blocker_fops = {
+	.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

[PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

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/power/suspend-blockers.txt |   17 ++++
 include/linux/suspend_block_dev.h        |   25 ++++++
 kernel/power/Kconfig                     |    9 ++
 kernel/power/Makefile                    |    1 +
 kernel/power/user_suspend_blocker.c      |  128 ++++++++++++++++++++++++++++++
 5 files changed, 180 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/suspend_block_dev.h
 create mode 100644 kernel/power/user_suspend_blocker.c

diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txt
index 1c48514..877bd8c 100644
--- a/Documentation/power/suspend-blockers.txt
+++ b/Documentation/power/suspend-blockers.txt
@@ -95,3 +95,20 @@ if (list_empty(&state->pending_work))
 else
 	suspend_block(&state->suspend_blocker);
 
+User-space API
+==============
+
+To create a suspend_blocker from user-space, open the suspend_blocker device:
+    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
+then call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
+
+To activate a suspend_blocker call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK);
+
+To unblock call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_UNBLOCK);
+
+To destroy the suspend_blocker, close the device:
+    close(fd);
+
diff --git a/include/linux/suspend_block_dev.h b/include/linux/suspend_block_dev.h
new file mode 100644
index 0000000..24bc5c7
--- /dev/null
+++ b/include/linux/suspend_block_dev.h
@@ -0,0 +1,25 @@
+/* include/linux/suspend_block_dev.h
+ *
+ * Copyright (C) 2009 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.
+ *
+ */
+
+#ifndef _LINUX_SUSPEND_BLOCK_DEV_H
+#define _LINUX_SUSPEND_BLOCK_DEV_H
+
+#include <linux/ioctl.h>
+
+#define SUSPEND_BLOCKER_IOCTL_INIT(len)		_IOC(_IOC_WRITE, 's', 0, len)
+#define SUSPEND_BLOCKER_IOCTL_BLOCK		_IO('s', 1)
+#define SUSPEND_BLOCKER_IOCTL_UNBLOCK		_IO('s', 2)
+
+#endif
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index f8fa246..1ac50ee 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -141,6 +141,15 @@ config SUSPEND_BLOCKERS
 	  state through /sys/power/state, the requested sleep state will be
 	  entered when no suspend blockers are active.
 
+config USER_SUSPEND_BLOCKERS
+	bool "Userspace suspend blockers"
+	depends on SUSPEND_BLOCKERS
+	default y
+	---help---
+	  User-space suspend block api. Creates a misc device with ioctls
+	  to create, block and unblock a suspend_blocker. The suspend_blocker
+	  will be deleted when the device is closed.
+
 config HIBERNATION_NVS
 	bool
 
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index f570801..80086c6 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_SUSPEND_BLOCKERS)	+= suspend_blocker.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..a9be6f4
--- /dev/null
+++ b/kernel/power/user_suspend_blocker.c
@@ -0,0 +1,128 @@
+/* kernel/power/user_suspend_block.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_blocker.h>
+#include <linux/suspend_block_dev.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);
+
+struct user_suspend_blocker {
+	struct suspend_blocker	blocker;
+	char			name[0];
+};
+
+static int create_user_suspend_blocker(struct file *file, void __user *name,
+				 size_t name_len)
+{
+	struct user_suspend_blocker *bl;
+	if (file->private_data)
+		return -EBUSY;
+	if (name_len > NAME_MAX)
+		return -ENAMETOOLONG;
+	bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
+	if (!bl)
+		return -ENOMEM;
+	if (copy_from_user(bl->name, name, name_len))
+		goto err_fault;
+	suspend_blocker_init(&bl->blocker, bl->name);
+	file->private_data = bl;
+	return 0;
+
+err_fault:
+	kfree(bl);
+	return -EFAULT;
+}
+
+static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
+				unsigned long _arg)
+{
+	void __user *arg = (void __user *)_arg;
+	struct user_suspend_blocker *bl;
+	long ret;
+
+	mutex_lock(&ioctl_lock);
+	if ((cmd & ~IOCSIZE_MASK) == SUSPEND_BLOCKER_IOCTL_INIT(0)) {
+		ret = create_user_suspend_blocker(file, arg, _IOC_SIZE(cmd));
+		goto done;
+	}
+	bl = file->private_data;
+	if (!bl) {
+		ret = -ENOENT;
+		goto done;
+	}
+	switch (cmd) {
+	case SUSPEND_BLOCKER_IOCTL_BLOCK:
+		suspend_block(&bl->blocker);
+		ret = 0;
+		break;
+	case SUSPEND_BLOCKER_IOCTL_UNBLOCK:
+		suspend_unblock(&bl->blocker);
+		ret = 0;
+		break;
+	default:
+		ret = -ENOTSUPP;
+	}
+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 *file)
+{
+	struct user_suspend_blocker *bl = file->private_data;
+	if (!bl)
+		return 0;
+	suspend_blocker_destroy(&bl->blocker);
+	kfree(bl);
+	return 0;
+}
+
+const struct file_operations user_suspend_blocker_fops = {
+	.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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linux-pm@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/linux-pm

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

2009/5/8 Rafael J. Wysocki <rjw@sisk.pl>:
> On Friday 08 May 2009, Arve Hjønnevåg wrote:
>> On Thu, May 7, 2009 at 3:32 AM, Pavel Machek <pavel@ucw.cz> wrote:
>> > On Wed 2009-05-06 18:42:59, Arve Hj?nnev?g wrote:
>> >> On Tue, May 5, 2009 at 1:12 PM, Pavel Machek <pavel@ucw.cz> wrote:
>> >> > Hi!
>> >> >
>> >> >> 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.
>> >> >
>> >> > Rafael proposed write() interface. I don't think you answered that.
>> >> >
>> >>
>> >> I think an ioctl interface makes more sense. With a write interface
>> >> you either have to do string parsing, or invent some other protocol
>> >> between the driver and user-space.
>> >
>> > Or perhaps just use "userspace/%d" % pid as a name?
>>
>> This would not be as useful. The point of naming the suspend blockers
>> is to that we can easily identify them in the stats and kernel logs.
>> Using the pid has two problems. First, the pid gives no hint about
>> what it is used for, you have to look up the process somewhere else.
>> Second, we use more than one suspend blocker from the same process.
>>
>> >
>> > 1) can't be faked that trivially
>>
>> I don't think this is a big problem. If you don't trust the apps that
>> you give suspend blocker access to use unique names, we can add a
>> prefix. This can be added in a later patch though.
>>
>> >
>> > 2) small / mostly fixed size
>> >
>> > 3) can use nicer write protocol?
>> >
>> I don't think a write protocol is nicer. "ioctl(suspend_block_fd,
>> SUSPEND_BLOCKER_IOCTL_BLOCK);" seems less error prone and more
>> readable to me than "write(suspend_block_fd, "1", 1);",
>> "write(suspend_block_fd, "1", 2);" or "suspend_block_val = 1;
>> write(suspend_block_fd, &suspend_block_val,
>> sizeof(suspend_block_val));".
>>
>> >> > kzalloc on user-supplied argument. Sounds like bad idea.
>> >> >
>> >> > Aha. And probably integer overflow in the same line. Ouch.
>> >> >
>> >>
>> >> The size is limited to _IOC_SIZEMASK with is 13 or 14 bits depending
>> >> on the architecture. Do you want a lower limit on the name length?
>> >
>> > 16K of unswappable kernel memory for name is a bit too much, yes.
>>
>> What if I just truncate it to NAME_MAX.
>
> My main concern with the ioctl() interface is that you're adding a device
> file just in order to have the ioctl()s available.  Usually, however, a device
> file's purpose is to implement file operations (open, close, read, write),
> while ioctl()s are used for doing things that the file operations are not
> suitable for.

In this case, we are adding a device file to get close (release).

> So, if your device only implements open(), close() and ioctl(), this is an
> indication that there's something wrong with the interface, because it doesn't
> do what one would generally expect it to do (ie. smells like an abuse).  That's
> why I think it would be better to use read() and write() instead of ioctl().

It not not clear to me how putting a control interface on top of read
and write is any less abusive.

> Of course, there also is a problem that people generally don't like adding new
> ioctl()s without a _really_ good reason.

ioctls are better suited for issuing commands than read/write.

-- 
Arve Hjønnevåg

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Rafael J. Wysocki]

On Friday 08 May 2009, Arve Hjønnevåg wrote:
> On Thu, May 7, 2009 at 3:32 AM, Pavel Machek <pavel@ucw.cz> wrote:
> > On Wed 2009-05-06 18:42:59, Arve Hj?nnev?g wrote:
> >> On Tue, May 5, 2009 at 1:12 PM, Pavel Machek <pavel@ucw.cz> wrote:
> >> > Hi!
> >> >
> >> >> 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.
> >> >
> >> > Rafael proposed write() interface. I don't think you answered that.
> >> >
> >>
> >> I think an ioctl interface makes more sense. With a write interface
> >> you either have to do string parsing, or invent some other protocol
> >> between the driver and user-space.
> >
> > Or perhaps just use "userspace/%d" % pid as a name?
> 
> This would not be as useful. The point of naming the suspend blockers
> is to that we can easily identify them in the stats and kernel logs.
> Using the pid has two problems. First, the pid gives no hint about
> what it is used for, you have to look up the process somewhere else.
> Second, we use more than one suspend blocker from the same process.
> 
> >
> > 1) can't be faked that trivially
> 
> I don't think this is a big problem. If you don't trust the apps that
> you give suspend blocker access to use unique names, we can add a
> prefix. This can be added in a later patch though.
> 
> >
> > 2) small / mostly fixed size
> >
> > 3) can use nicer write protocol?
> >
> I don't think a write protocol is nicer. "ioctl(suspend_block_fd,
> SUSPEND_BLOCKER_IOCTL_BLOCK);" seems less error prone and more
> readable to me than "write(suspend_block_fd, "1", 1);",
> "write(suspend_block_fd, "1", 2);" or "suspend_block_val = 1;
> write(suspend_block_fd, &suspend_block_val,
> sizeof(suspend_block_val));".
> 
> >> > kzalloc on user-supplied argument. Sounds like bad idea.
> >> >
> >> > Aha. And probably integer overflow in the same line. Ouch.
> >> >
> >>
> >> The size is limited to _IOC_SIZEMASK with is 13 or 14 bits depending
> >> on the architecture. Do you want a lower limit on the name length?
> >
> > 16K of unswappable kernel memory for name is a bit too much, yes.
> 
> What if I just truncate it to NAME_MAX.

My main concern with the ioctl() interface is that you're adding a device
file just in order to have the ioctl()s available.  Usually, however, a device
file's purpose is to implement file operations (open, close, read, write),
while ioctl()s are used for doing things that the file operations are not
suitable for.

So, if your device only implements open(), close() and ioctl(), this is an
indication that there's something wrong with the interface, because it doesn't
do what one would generally expect it to do (ie. smells like an abuse).  That's
why I think it would be better to use read() and write() instead of ioctl().

Of course, there also is a problem that people generally don't like adding new
ioctl()s without a _really_ good reason.

Thanks,
Rafael

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

On Thu, May 7, 2009 at 3:32 AM, Pavel Machek <pavel@ucw.cz> wrote:
> On Wed 2009-05-06 18:42:59, Arve Hj?nnev?g wrote:
>> On Tue, May 5, 2009 at 1:12 PM, Pavel Machek <pavel@ucw.cz> wrote:
>> > Hi!
>> >
>> >> 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.
>> >
>> > Rafael proposed write() interface. I don't think you answered that.
>> >
>>
>> I think an ioctl interface makes more sense. With a write interface
>> you either have to do string parsing, or invent some other protocol
>> between the driver and user-space.
>
> Or perhaps just use "userspace/%d" % pid as a name?

This would not be as useful. The point of naming the suspend blockers
is to that we can easily identify them in the stats and kernel logs.
Using the pid has two problems. First, the pid gives no hint about
what it is used for, you have to look up the process somewhere else.
Second, we use more than one suspend blocker from the same process.

>
> 1) can't be faked that trivially

I don't think this is a big problem. If you don't trust the apps that
you give suspend blocker access to use unique names, we can add a
prefix. This can be added in a later patch though.

>
> 2) small / mostly fixed size
>
> 3) can use nicer write protocol?
>
I don't think a write protocol is nicer. "ioctl(suspend_block_fd,
SUSPEND_BLOCKER_IOCTL_BLOCK);" seems less error prone and more
readable to me than "write(suspend_block_fd, "1", 1);",
"write(suspend_block_fd, "1", 2);" or "suspend_block_val = 1;
write(suspend_block_fd, &suspend_block_val,
sizeof(suspend_block_val));".

>> > kzalloc on user-supplied argument. Sounds like bad idea.
>> >
>> > Aha. And probably integer overflow in the same line. Ouch.
>> >
>>
>> The size is limited to _IOC_SIZEMASK with is 13 or 14 bits depending
>> on the architecture. Do you want a lower limit on the name length?
>
> 16K of unswappable kernel memory for name is a bit too much, yes.

What if I just truncate it to NAME_MAX.

-- 
Arve Hjønnevåg

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

On Wed 2009-05-06 18:31:36, Arve Hj?nnev?g wrote:
> On Tue, May 5, 2009 at 1:16 PM, Pavel Machek <pavel@ucw.cz> wrote:
> > On Tue 2009-05-05 21:18:42, Arve Hj??nnev??g wrote:
> >> 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.
> >>
> >
> >> +static int create_user_suspend_blocker(struct file *file, void __user *name,
> >> +                              size_t name_len)
> >> +{
> >> +     struct user_suspend_blocker *bl;
> >> +     if (file->private_data)
> >> +             return -EBUSY;
> >> +     bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
> > ...
> >> +static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
> >> +                             unsigned long _arg)
> >> +{
> >> +     void __user *arg = (void __user *)_arg;
> >> +     struct user_suspend_blocker *bl;
> >> +     long ret;
> >> +
> >> +     mutex_lock(&ioctl_lock);
> >> +     if ((cmd & ~IOCSIZE_MASK) == SUSPEND_BLOCKER_IOCTL_INIT(0)) {
> >> +             ret = create_user_suspend_blocker(file, arg, _IOC_SIZE(cmd));
> >> +             goto done;
> >> +     }
> >
> > Wait a moment, wtf is this? Not one ioctl but one ioctl per length of
> > string?!
> 
> This is not uncommon. _IOC encodes the size of the argument, and if
> this is not a fixed size, then the raw ioctl number change based on
> the size passed in. Look at input.h is you want other examples of
> this.

Ok, I found few examples in code:

pavel@amd:/data/l/linux$ grep -ri IOCSIZE_MASK .
./arch/alpha/include/asm/ioctl.h:#define IOCSIZE_MASK	(_IOC_SIZEMASK
<< _IOC_SIZESHIFT)
./arch/mips/include/asm/ioctl.h:#define IOCSIZE_MASK	(_IOC_SIZEMASK
<< _IOC_SIZESHIFT)
./arch/sparc/include/asm/ioctl.h:#define IOCSIZE_MASK
(_IOC_XSIZEMASK << _IOC_SIZESHIFT)
./drivers/input/joydev.c:		if ((cmd & ~IOCSIZE_MASK) ==
JSIOCGNAME(0)) {
./drivers/message/fusion/mptctl.c:	if ((cmd & ~IOCSIZE_MASK) ==
(MPTIOCINFO & ~IOCSIZE_MASK)) {
./drivers/message/fusion/mptctl.c:	else if ((cmd & ~IOCSIZE_MASK)
== (HP_GETHOSTINFO & ~IOCSIZE_MASK))
./drivers/mtd/mtdchar.c:	size = (cmd & IOCSIZE_MASK) >>
IOCSIZE_SHIFT;
./drivers/pcmcia/pcmcia_ioctl.c:    size = (cmd & IOCSIZE_MASK) >>
IOCSIZE_SHIFT;
./include/asm-generic/ioctl.h:#define IOCSIZE_MASK	(_IOC_SIZEMASK
<< _IOC_SIZESHIFT)

I still do not like introducing 16000 ioctls, and I'm not sure how our
ioctl compatibility layer playes with this.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

On Wed 2009-05-06 18:42:59, Arve Hj?nnev?g wrote:
> On Tue, May 5, 2009 at 1:12 PM, Pavel Machek <pavel@ucw.cz> wrote:
> > Hi!
> >
> >> 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.
> >
> > Rafael proposed write() interface. I don't think you answered that.
> >
> 
> I think an ioctl interface makes more sense. With a write interface
> you either have to do string parsing, or invent some other protocol
> between the driver and user-space.

Or perhaps just use "userspace/%d" % pid as a name?

1) can't be faked that trivially

2) small / mostly fixed size

3) can use nicer write protocol?

> > kzalloc on user-supplied argument. Sounds like bad idea.
> >
> > Aha. And probably integer overflow in the same line. Ouch.
> >
> 
> The size is limited to _IOC_SIZEMASK with is 13 or 14 bits depending
> on the architecture. Do you want a lower limit on the name length?

16K of unswappable kernel memory for name is a bit too much, yes.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

On Tue, May 5, 2009 at 1:12 PM, Pavel Machek <pavel@ucw.cz> wrote:
> Hi!
>
>> 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.
>
> Rafael proposed write() interface. I don't think you answered that.
>

I think an ioctl interface makes more sense. With a write interface
you either have to do string parsing, or invent some other protocol
between the driver and user-space.

>
>> +static int create_user_suspend_blocker(struct file *file, void __user *name,
>> +                              size_t name_len)
>> +{
>> +     struct user_suspend_blocker *bl;
>> +     if (file->private_data)
>> +             return -EBUSY;
>> +     bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
>> +     if (!bl)
>> +             return -ENOMEM;
>> +     if (copy_from_user(bl->name, name, name_len))
>> +             goto err_fault;
>> +     suspend_blocker_init(&bl->blocker, bl->name);
>> +     file->private_data = bl;
>> +     return 0;
>
> kzalloc on user-supplied argument. Sounds like bad idea.
>
> Aha. And probably integer overflow in the same line. Ouch.
>

The size is limited to _IOC_SIZEMASK with is 13 or 14 bits depending
on the architecture. Do you want a lower limit on the name length?

> Plus you actually 'trust' the string from userspace. Someone passes
> "evdev" there and can masquerade as a part of kernel.

Yes. I could add a prefix to userspace names, but it did not seem
worth the effort since the name is not used as a key for anything.

>
>> +static int user_suspend_blocker_release(struct inode *inode, struct file *file)
>> +{
>> +     struct user_suspend_blocker *bl = file->private_data;
>> +     if (!bl)
>> +             return 0;
>> +     suspend_blocker_destroy(&bl->blocker);
>> +     kfree(bl);
>> +     return 0;
>> +}
>
> What happens if someone does dup() on such file descriptor?
>

Then you have two file descriptors pointing to the same suspend
blocker. Release is called when the last reference goes away.

-- 
Arve Hjønnevåg

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

On Tue, May 5, 2009 at 1:16 PM, Pavel Machek <pavel@ucw.cz> wrote:
> On Tue 2009-05-05 21:18:42, Arve Hj??nnev??g wrote:
>> 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.
>>
>
>> +static int create_user_suspend_blocker(struct file *file, void __user *name,
>> +                              size_t name_len)
>> +{
>> +     struct user_suspend_blocker *bl;
>> +     if (file->private_data)
>> +             return -EBUSY;
>> +     bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
> ...
>> +static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
>> +                             unsigned long _arg)
>> +{
>> +     void __user *arg = (void __user *)_arg;
>> +     struct user_suspend_blocker *bl;
>> +     long ret;
>> +
>> +     mutex_lock(&ioctl_lock);
>> +     if ((cmd & ~IOCSIZE_MASK) == SUSPEND_BLOCKER_IOCTL_INIT(0)) {
>> +             ret = create_user_suspend_blocker(file, arg, _IOC_SIZE(cmd));
>> +             goto done;
>> +     }
>
> Wait a moment, wtf is this? Not one ioctl but one ioctl per length of
> string?!

This is not uncommon. _IOC encodes the size of the argument, and if
this is not a fixed size, then the raw ioctl number change based on
the size passed in. Look at input.h is you want other examples of
this.

-- 
Arve Hjønnevåg

[PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Arve Hjønnevåg]

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/power/suspend-blockers.txt |   17 ++++
 include/linux/suspend_block_dev.h        |   25 ++++++
 kernel/power/Kconfig                     |    9 ++
 kernel/power/Makefile                    |    1 +
 kernel/power/user_suspend_blocker.c      |  125 ++++++++++++++++++++++++++++++
 5 files changed, 177 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/suspend_block_dev.h
 create mode 100644 kernel/power/user_suspend_blocker.c

diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txt
index 5a33ed6..9d78d4e 100644
--- a/Documentation/power/suspend-blockers.txt
+++ b/Documentation/power/suspend-blockers.txt
@@ -92,3 +92,20 @@ if (list_empty(&state->pending_work))
 else
 	suspend_block(&state->suspend_blocker);
 
+User-space API
+==============
+
+To create a suspend_blocker from user-space, open the suspend_blocker device:
+    fd = open("/dev/suspend_blocker", O_RDWR | O_CLOEXEC);
+then call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_INIT(strlen(name)), name);
+
+To activate a suspend_blocker call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_BLOCK);
+
+To unblock call:
+    ioctl(fd, SUSPEND_BLOCKER_IOCTL_UNBLOCK);
+
+To destroy the suspend_blocker, close the device:
+    close(fd);
+
diff --git a/include/linux/suspend_block_dev.h b/include/linux/suspend_block_dev.h
new file mode 100644
index 0000000..a7c0bf9
--- /dev/null
+++ b/include/linux/suspend_block_dev.h
@@ -0,0 +1,25 @@
+/* include/linux/suspend_block_dev.h
+ *
+ * Copyright (C) 2009 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.
+ *
+ */
+
+#ifndef _LINUX_SUSPEND_BLOCK_DEV_H
+#define _LINUX_SUSPEND_BLOCK_DEV_H
+
+#include <linux/ioctl.h>
+
+#define SUSPEND_BLOCKER_IOCTL_INIT(len)		_IOC(_IOC_WRITE, 's', 0, len)
+#define SUSPEND_BLOCKER_IOCTL_BLOCK		_IO('s', 1)
+#define SUSPEND_BLOCKER_IOCTL_UNBLOCK		_IO('s', 3)
+
+#endif
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index a3587d3..84b423f 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -126,6 +126,15 @@ config SUSPEND_BLOCKERS
 	  through /sys/power/request_state, the requested sleep state will be
 	  entered when no suspend blockers are active.
 
+config USER_SUSPEND_BLOCKERS
+	bool "Userspace suspend blockers"
+	depends on SUSPEND_BLOCKERS
+	default y
+	---help---
+	  User-space suspend block api. Creates a misc device with ioctls
+	  to create, block and unblock a suspend_blocker. The suspend_blocker
+	  will be deleted when the device is closed.
+
 config HIBERNATION
 	bool "Hibernation (aka 'suspend to disk')"
 	depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index e8c7f85..24ade91 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_PM)		+= main.o
 obj-$(CONFIG_PM_SLEEP)		+= console.o
 obj-$(CONFIG_FREEZER)		+= process.o
 obj-$(CONFIG_SUSPEND_BLOCKERS)	+= suspend_blocker.o
+obj-$(CONFIG_USER_SUSPEND_BLOCKERS)	+= user_suspend_blocker.o
 obj-$(CONFIG_HIBERNATION)	+= swsusp.o disk.o snapshot.o swap.o user.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
diff --git a/kernel/power/user_suspend_blocker.c b/kernel/power/user_suspend_blocker.c
new file mode 100644
index 0000000..69b3ddb
--- /dev/null
+++ b/kernel/power/user_suspend_blocker.c
@@ -0,0 +1,125 @@
+/* kernel/power/user_suspend_block.c
+ *
+ * Copyright (C) 2009 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/suspend_blocker.h>
+#include <linux/suspend_block_dev.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);
+
+struct user_suspend_blocker {
+	struct suspend_blocker	blocker;
+	char			name[0];
+};
+
+static int create_user_suspend_blocker(struct file *file, void __user *name,
+				 size_t name_len)
+{
+	struct user_suspend_blocker *bl;
+	if (file->private_data)
+		return -EBUSY;
+	bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
+	if (!bl)
+		return -ENOMEM;
+	if (copy_from_user(bl->name, name, name_len))
+		goto err_fault;
+	suspend_blocker_init(&bl->blocker, bl->name);
+	file->private_data = bl;
+	return 0;
+
+err_fault:
+	kfree(bl);
+	return -EFAULT;
+}
+
+static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
+				unsigned long _arg)
+{
+	void __user *arg = (void __user *)_arg;
+	struct user_suspend_blocker *bl;
+	long ret;
+
+	mutex_lock(&ioctl_lock);
+	if ((cmd & ~IOCSIZE_MASK) == SUSPEND_BLOCKER_IOCTL_INIT(0)) {
+		ret = create_user_suspend_blocker(file, arg, _IOC_SIZE(cmd));
+		goto done;
+	}
+	bl = file->private_data;
+	if (!bl) {
+		ret = -ENOENT;
+		goto done;
+	}
+	switch (cmd) {
+	case SUSPEND_BLOCKER_IOCTL_BLOCK:
+		suspend_block(&bl->blocker);
+		ret = 0;
+		break;
+	case SUSPEND_BLOCKER_IOCTL_UNBLOCK:
+		suspend_unblock(&bl->blocker);
+		ret = 0;
+		break;
+	default:
+		ret = -ENOTSUPP;
+	}
+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 *file)
+{
+	struct user_suspend_blocker *bl = file->private_data;
+	if (!bl)
+		return 0;
+	suspend_blocker_destroy(&bl->blocker);
+	kfree(bl);
+	return 0;
+}
+
+const struct file_operations user_suspend_blocker_fops = {
+	.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);
-- 
1.6.1

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Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

On Tue 2009-05-05 21:18:42, Arve Hj??nnev??g wrote:
> 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.
> 

> +static int create_user_suspend_blocker(struct file *file, void __user *name,
> +				 size_t name_len)
> +{
> +	struct user_suspend_blocker *bl;
> +	if (file->private_data)
> +		return -EBUSY;
> +	bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
...
> +static long user_suspend_blocker_ioctl(struct file *file, unsigned int cmd,
> +				unsigned long _arg)
> +{
> +	void __user *arg = (void __user *)_arg;
> +	struct user_suspend_blocker *bl;
> +	long ret;
> +
> +	mutex_lock(&ioctl_lock);
> +	if ((cmd & ~IOCSIZE_MASK) == SUSPEND_BLOCKER_IOCTL_INIT(0)) {
> +		ret = create_user_suspend_blocker(file, arg, _IOC_SIZE(cmd));
> +		goto done;
> +	}

Wait a moment, wtf is this? Not one ioctl but one ioctl per length of
string?!

								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space

[Pavel Machek]

Hi!

> 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.

Rafael proposed write() interface. I don't think you answered that.


> +static int create_user_suspend_blocker(struct file *file, void __user *name,
> +				 size_t name_len)
> +{
> +	struct user_suspend_blocker *bl;
> +	if (file->private_data)
> +		return -EBUSY;
> +	bl = kzalloc(sizeof(*bl) + name_len + 1, GFP_KERNEL);
> +	if (!bl)
> +		return -ENOMEM;
> +	if (copy_from_user(bl->name, name, name_len))
> +		goto err_fault;
> +	suspend_blocker_init(&bl->blocker, bl->name);
> +	file->private_data = bl;
> +	return 0;

kzalloc on user-supplied argument. Sounds like bad idea.

Aha. And probably integer overflow in the same line. Ouch.

Plus you actually 'trust' the string from userspace. Someone passes
"evdev" there and can masquerade as a part of kernel.

> +static int user_suspend_blocker_release(struct inode *inode, struct file *file)
> +{
> +	struct user_suspend_blocker *bl = file->private_data;
> +	if (!bl)
> +		return 0;
> +	suspend_blocker_destroy(&bl->blocker);
> +	kfree(bl);
> +	return 0;
> +}

What happens if someone does dup() on such file descriptor? 


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html