diff options
| -rw-r--r-- | drivers/char/apm-emulation.c | 346 |
1 files changed, 207 insertions, 139 deletions
diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c index da8a1658a273..aaca40283be9 100644 --- a/drivers/char/apm-emulation.c +++ b/drivers/char/apm-emulation.c @@ -59,6 +59,55 @@ struct apm_queue { }; /* + * 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 */ struct apm_user { @@ -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. - */ - 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. + * Just invoke pm_suspend(), we'll handle it from + * there via the notifier. */ - 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); |