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APM emulation: Notify about all suspend events, not just APM invoked ones (v2) 

This revamps the apm-emulation code to get suspend notifications
regardless of what way pm_suspend() was invoked, whether via the
apm ioctl or via /sys/power/state. Also do some code cleanup and
add comments while at it.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
This commit is contained in:
Johannes Berg 2008-06-11 22:03:10 +02:00 committed by Andi Kleen
parent 741438b500
commit d20a4dca47
1 changed files with 207 additions and 139 deletions
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346
drivers/char/apm-emulation.c
View File

@ -58,6 +58,55 @@ struct apm_queue {
apm_event_t events[APM_MAX_EVENTS];
};
/*
* thread states (for threads using a writable /dev/apm_bios fd):
*
* SUSPEND_NONE: nothing happening
* SUSPEND_PENDING: suspend event queued for thread and pending to be read
* SUSPEND_READ: suspend event read, pending acknowledgement
* SUSPEND_ACKED: acknowledgement received from thread (via ioctl),
* waiting for resume
* SUSPEND_ACKTO: acknowledgement timeout
* SUSPEND_DONE: thread had acked suspend and is now notified of
* resume
*
* SUSPEND_WAIT: this thread invoked suspend and is waiting for resume
*
* A thread migrates in one of three paths:
* NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
* -6-> ACKTO -7-> NONE
* NONE -8-> WAIT -9-> NONE
*
* While in PENDING or READ, the thread is accounted for in the
* suspend_acks_pending counter.
*
* The transitions are invoked as follows:
* 1: suspend event is signalled from the core PM code
* 2: the suspend event is read from the fd by the userspace thread
* 3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
* 4: core PM code signals that we have resumed
* 5: APM_IOC_SUSPEND ioctl returns
*
* 6: the notifier invoked from the core PM code timed out waiting
* for all relevant threds to enter ACKED state and puts those
* that haven't into ACKTO
* 7: those threads issue APM_IOC_SUSPEND ioctl too late,
* get an error
*
* 8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
* ioctl code invokes pm_suspend()
* 9: pm_suspend() returns indicating resume
*/
enum apm_suspend_state {
SUSPEND_NONE,
SUSPEND_PENDING,
SUSPEND_READ,
SUSPEND_ACKED,
SUSPEND_ACKTO,
SUSPEND_WAIT,
SUSPEND_DONE,
};
/*
* The per-file APM data
*/
@ -69,13 +118,7 @@ struct apm_user {
unsigned int reader: 1;
int suspend_result;
unsigned int suspend_state;
#define SUSPEND_NONE 0 /* no suspend pending */
#define SUSPEND_PENDING 1 /* suspend pending read */
#define SUSPEND_READ 2 /* suspend read, pending ack */
#define SUSPEND_ACKED 3 /* suspend acked */
#define SUSPEND_WAIT 4 /* waiting for suspend */
#define SUSPEND_DONE 5 /* suspend completed */
enum apm_suspend_state suspend_state;
struct apm_queue queue;
};
@ -83,7 +126,8 @@ struct apm_user {
/*
* Local variables
*/
static int suspends_pending;
static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
static int apm_disabled;
static struct task_struct *kapmd_tsk;
@ -166,78 +210,6 @@ static void queue_event(apm_event_t event)
wake_up_interruptible(&apm_waitqueue);
}
/*
* queue_suspend_event - queue an APM suspend event.
*
* Check that we're in a state where we can suspend. If not,
* return -EBUSY. Otherwise, queue an event to all "writer"
* users. If there are no "writer" users, return '1' to
* indicate that we can immediately suspend.
*/
static int queue_suspend_event(apm_event_t event, struct apm_user *sender)
{
struct apm_user *as;
int ret = 1;
mutex_lock(&state_lock);
down_read(&user_list_lock);
/*
* If a thread is still processing, we can't suspend, so reject
* the request.
*/
list_for_each_entry(as, &apm_user_list, list) {
if (as != sender && as->reader && as->writer && as->suser &&
as->suspend_state != SUSPEND_NONE) {
ret = -EBUSY;
goto out;
}
}
list_for_each_entry(as, &apm_user_list, list) {
if (as != sender && as->reader && as->writer && as->suser) {
as->suspend_state = SUSPEND_PENDING;
suspends_pending++;
queue_add_event(&as->queue, event);
ret = 0;
}
}
out:
up_read(&user_list_lock);
mutex_unlock(&state_lock);
wake_up_interruptible(&apm_waitqueue);
return ret;
}
static void apm_suspend(void)
{
struct apm_user *as;
int err = pm_suspend(PM_SUSPEND_MEM);
/*
* Anyone on the APM queues will think we're still suspended.
* Send a message so everyone knows we're now awake again.
*/
queue_event(APM_NORMAL_RESUME);
/*
* Finally, wake up anyone who is sleeping on the suspend.
*/
mutex_lock(&state_lock);
down_read(&user_list_lock);
list_for_each_entry(as, &apm_user_list, list) {
if (as->suspend_state == SUSPEND_WAIT ||
as->suspend_state == SUSPEND_ACKED) {
as->suspend_result = err;
as->suspend_state = SUSPEND_DONE;
}
}
up_read(&user_list_lock);
mutex_unlock(&state_lock);
wake_up(&apm_suspend_waitqueue);
}
static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
{
struct apm_user *as = fp->private_data;
@ -308,25 +280,22 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
as->suspend_result = -EINTR;
if (as->suspend_state == SUSPEND_READ) {
int pending;
switch (as->suspend_state) {
case SUSPEND_READ:
/*
* If we read a suspend command from /dev/apm_bios,
* then the corresponding APM_IOC_SUSPEND ioctl is
* interpreted as an acknowledge.
*/
as->suspend_state = SUSPEND_ACKED;
suspends_pending--;
pending = suspends_pending == 0;
atomic_dec(&suspend_acks_pending);
mutex_unlock(&state_lock);
/*
* If there are no further acknowledges required,
* suspend the system.
* suspend_acks_pending changed, the notifier needs to
* be woken up for this
*/
if (pending)
apm_suspend();
wake_up(&apm_suspend_waitqueue);
/*
* Wait for the suspend/resume to complete. If there
@ -342,35 +311,21 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
* try_to_freeze() in freezer_count() will not trigger
*/
freezer_count();
} else {
break;
case SUSPEND_ACKTO:
as->suspend_result = -ETIMEDOUT;
mutex_unlock(&state_lock);
break;
default:
as->suspend_state = SUSPEND_WAIT;
mutex_unlock(&state_lock);
/*
* Otherwise it is a request to suspend the system.
* Queue an event for all readers, and expect an
* acknowledge from all writers who haven't already
* acknowledged.
* Just invoke pm_suspend(), we'll handle it from
* there via the notifier.
*/
err = queue_suspend_event(APM_USER_SUSPEND, as);
if (err < 0) {
/*
* Avoid taking the lock here - this
* should be fine.
*/
as->suspend_state = SUSPEND_NONE;
break;
}
if (err > 0)
apm_suspend();
/*
* Wait for the suspend/resume to complete. If there
* are pending acknowledges, we wait here for them.
*/
wait_event_freezable(apm_suspend_waitqueue,
as->suspend_state == SUSPEND_DONE);
as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
}
mutex_lock(&state_lock);
@ -386,7 +341,6 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
static int apm_release(struct inode * inode, struct file * filp)
{
struct apm_user *as = filp->private_data;
int pending = 0;
filp->private_data = NULL;
@ -396,18 +350,15 @@ static int apm_release(struct inode * inode, struct file * filp)
/*
* We are now unhooked from the chain. As far as new
* events are concerned, we no longer exist. However, we
* need to balance suspends_pending, which means the
* possibility of sleeping.
* events are concerned, we no longer exist.
*/
mutex_lock(&state_lock);
if (as->suspend_state != SUSPEND_NONE) {
suspends_pending -= 1;
pending = suspends_pending == 0;
}
if (as->suspend_state == SUSPEND_PENDING ||
as->suspend_state == SUSPEND_READ)
atomic_dec(&suspend_acks_pending);
mutex_unlock(&state_lock);
if (pending)
apm_suspend();
wake_up(&apm_suspend_waitqueue);
kfree(as);
return 0;
@ -545,7 +496,6 @@ static int kapmd(void *arg)
{
do {
apm_event_t event;
int ret;
wait_event_interruptible(kapmd_wait,
!queue_empty(&kapmd_queue) || kthread_should_stop());
@ -570,20 +520,13 @@ static int kapmd(void *arg)
case APM_USER_SUSPEND:
case APM_SYS_SUSPEND:
ret = queue_suspend_event(event, NULL);
if (ret < 0) {
/*
* We were busy. Try again in 50ms.
*/
queue_add_event(&kapmd_queue, event);
msleep(50);
}
if (ret > 0)
apm_suspend();
pm_suspend(PM_SUSPEND_MEM);
break;
case APM_CRITICAL_SUSPEND:
apm_suspend();
atomic_inc(&userspace_notification_inhibit);
pm_suspend(PM_SUSPEND_MEM);
atomic_dec(&userspace_notification_inhibit);
break;
}
} while (1);
@ -591,6 +534,120 @@ static int kapmd(void *arg)
return 0;
}
static int apm_suspend_notifier(struct notifier_block *nb,
unsigned long event,
void *dummy)
{
struct apm_user *as;
int err;
/* short-cut emergency suspends */
if (atomic_read(&userspace_notification_inhibit))
return NOTIFY_DONE;
switch (event) {
case PM_SUSPEND_PREPARE:
/*
* Queue an event to all "writer" users that we want
* to suspend and need their ack.
*/
mutex_lock(&state_lock);
down_read(&user_list_lock);
list_for_each_entry(as, &apm_user_list, list) {
if (as->suspend_state != SUSPEND_WAIT && as->reader &&
as->writer && as->suser) {
as->suspend_state = SUSPEND_PENDING;
atomic_inc(&suspend_acks_pending);
queue_add_event(&as->queue, APM_USER_SUSPEND);
}
}
up_read(&user_list_lock);
mutex_unlock(&state_lock);
wake_up_interruptible(&apm_waitqueue);
/*
* Wait for the the suspend_acks_pending variable to drop to
* zero, meaning everybody acked the suspend event (or the
* process was killed.)
*
* If the app won't answer within a short while we assume it
* locked up and ignore it.
*/
err = wait_event_interruptible_timeout(
apm_suspend_waitqueue,
atomic_read(&suspend_acks_pending) == 0,
5*HZ);
/* timed out */
if (err == 0) {
/*
* Move anybody who timed out to "ack timeout" state.
*
* We could time out and the userspace does the ACK
* right after we time out but before we enter the
* locked section here, but that's fine.
*/
mutex_lock(&state_lock);
down_read(&user_list_lock);
list_for_each_entry(as, &apm_user_list, list) {
if (as->suspend_state == SUSPEND_PENDING ||
as->suspend_state == SUSPEND_READ) {
as->suspend_state = SUSPEND_ACKTO;
atomic_dec(&suspend_acks_pending);
}
}
up_read(&user_list_lock);
mutex_unlock(&state_lock);
}
/* let suspend proceed */
if (err >= 0)
return NOTIFY_OK;
/* interrupted by signal */
return NOTIFY_BAD;
case PM_POST_SUSPEND:
/*
* Anyone on the APM queues will think we're still suspended.
* Send a message so everyone knows we're now awake again.
*/
queue_event(APM_NORMAL_RESUME);
/*
* Finally, wake up anyone who is sleeping on the suspend.
*/
mutex_lock(&state_lock);
down_read(&user_list_lock);
list_for_each_entry(as, &apm_user_list, list) {
if (as->suspend_state == SUSPEND_ACKED) {
/*
* TODO: maybe grab error code, needs core
* changes to push the error to the notifier
* chain (could use the second parameter if
* implemented)
*/
as->suspend_result = 0;
as->suspend_state = SUSPEND_DONE;
}
}
up_read(&user_list_lock);
mutex_unlock(&state_lock);
wake_up(&apm_suspend_waitqueue);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
static struct notifier_block apm_notif_block = {
.notifier_call = apm_suspend_notifier,
};
static int __init apm_init(void)
{
int ret;
@ -604,7 +661,7 @@ static int __init apm_init(void)
if (IS_ERR(kapmd_tsk)) {
ret = PTR_ERR(kapmd_tsk);
kapmd_tsk = NULL;
return ret;
goto out;
}
wake_up_process(kapmd_tsk);
@ -613,16 +670,27 @@ static int __init apm_init(void)
#endif
ret = misc_register(&apm_device);
if (ret != 0) {
remove_proc_entry("apm", NULL);
kthread_stop(kapmd_tsk);
}
if (ret)
goto out_stop;
ret = register_pm_notifier(&apm_notif_block);
if (ret)
goto out_unregister;
return 0;
out_unregister:
misc_deregister(&apm_device);
out_stop:
remove_proc_entry("apm", NULL);
kthread_stop(kapmd_tsk);
out:
return ret;
}
static void __exit apm_exit(void)
{
unregister_pm_notifier(&apm_notif_block);
misc_deregister(&apm_device);
remove_proc_entry("apm", NULL);