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fb9d78aca7
Pull an APM fix from Jiri Kosina: "One deadlock/race fix from Niel that got introduced when we were moving away from freezer_*_count() to wait_event_freezable()." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/apm: APM: fix deadlock in APM_IOC_SUSPEND ioctl
739 lines
17 KiB
C
739 lines
17 KiB
C
/*
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* bios-less APM driver for ARM Linux
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* Jamey Hicks <jamey@crl.dec.com>
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* adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
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*
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* APM 1.2 Reference:
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* Intel Corporation, Microsoft Corporation. Advanced Power Management
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* (APM) BIOS Interface Specification, Revision 1.2, February 1996.
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*
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* This document is available from Microsoft at:
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* http://www.microsoft.com/whdc/archive/amp_12.mspx
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*/
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#include <linux/module.h>
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#include <linux/poll.h>
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/miscdevice.h>
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#include <linux/apm_bios.h>
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#include <linux/capability.h>
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#include <linux/sched.h>
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#include <linux/suspend.h>
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#include <linux/apm-emulation.h>
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#include <linux/freezer.h>
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#include <linux/device.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/init.h>
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#include <linux/completion.h>
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#include <linux/kthread.h>
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#include <linux/delay.h>
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/*
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* The apm_bios device is one of the misc char devices.
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* This is its minor number.
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*/
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#define APM_MINOR_DEV 134
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/*
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* One option can be changed at boot time as follows:
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* apm=on/off enable/disable APM
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*/
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/*
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* Maximum number of events stored
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*/
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#define APM_MAX_EVENTS 16
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struct apm_queue {
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unsigned int event_head;
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unsigned int event_tail;
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apm_event_t events[APM_MAX_EVENTS];
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};
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/*
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* thread states (for threads using a writable /dev/apm_bios fd):
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*
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* SUSPEND_NONE: nothing happening
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* SUSPEND_PENDING: suspend event queued for thread and pending to be read
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* SUSPEND_READ: suspend event read, pending acknowledgement
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* SUSPEND_ACKED: acknowledgement received from thread (via ioctl),
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* waiting for resume
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* SUSPEND_ACKTO: acknowledgement timeout
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* SUSPEND_DONE: thread had acked suspend and is now notified of
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* resume
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*
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* SUSPEND_WAIT: this thread invoked suspend and is waiting for resume
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*
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* A thread migrates in one of three paths:
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* NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
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* -6-> ACKTO -7-> NONE
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* NONE -8-> WAIT -9-> NONE
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*
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* While in PENDING or READ, the thread is accounted for in the
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* suspend_acks_pending counter.
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*
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* The transitions are invoked as follows:
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* 1: suspend event is signalled from the core PM code
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* 2: the suspend event is read from the fd by the userspace thread
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* 3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
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* 4: core PM code signals that we have resumed
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* 5: APM_IOC_SUSPEND ioctl returns
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*
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* 6: the notifier invoked from the core PM code timed out waiting
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* for all relevant threds to enter ACKED state and puts those
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* that haven't into ACKTO
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* 7: those threads issue APM_IOC_SUSPEND ioctl too late,
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* get an error
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*
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* 8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
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* ioctl code invokes pm_suspend()
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* 9: pm_suspend() returns indicating resume
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*/
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enum apm_suspend_state {
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SUSPEND_NONE,
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SUSPEND_PENDING,
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SUSPEND_READ,
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SUSPEND_ACKED,
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SUSPEND_ACKTO,
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SUSPEND_WAIT,
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SUSPEND_DONE,
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};
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/*
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* The per-file APM data
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*/
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struct apm_user {
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struct list_head list;
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unsigned int suser: 1;
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unsigned int writer: 1;
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unsigned int reader: 1;
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int suspend_result;
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enum apm_suspend_state suspend_state;
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struct apm_queue queue;
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};
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/*
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* Local variables
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*/
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static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
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static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
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static int apm_disabled;
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static struct task_struct *kapmd_tsk;
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static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
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static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
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/*
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* This is a list of everyone who has opened /dev/apm_bios
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*/
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static DECLARE_RWSEM(user_list_lock);
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static LIST_HEAD(apm_user_list);
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/*
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* kapmd info. kapmd provides us a process context to handle
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* "APM" events within - specifically necessary if we're going
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* to be suspending the system.
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*/
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static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
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static DEFINE_SPINLOCK(kapmd_queue_lock);
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static struct apm_queue kapmd_queue;
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static DEFINE_MUTEX(state_lock);
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static const char driver_version[] = "1.13"; /* no spaces */
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/*
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* Compatibility cruft until the IPAQ people move over to the new
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* interface.
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*/
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static void __apm_get_power_status(struct apm_power_info *info)
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{
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}
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/*
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* This allows machines to provide their own "apm get power status" function.
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*/
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void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
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EXPORT_SYMBOL(apm_get_power_status);
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/*
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* APM event queue management.
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*/
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static inline int queue_empty(struct apm_queue *q)
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{
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return q->event_head == q->event_tail;
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}
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static inline apm_event_t queue_get_event(struct apm_queue *q)
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{
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q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
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return q->events[q->event_tail];
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}
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static void queue_add_event(struct apm_queue *q, apm_event_t event)
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{
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q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
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if (q->event_head == q->event_tail) {
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static int notified;
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if (notified++ == 0)
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printk(KERN_ERR "apm: an event queue overflowed\n");
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q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
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}
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q->events[q->event_head] = event;
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}
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static void queue_event(apm_event_t event)
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{
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struct apm_user *as;
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down_read(&user_list_lock);
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list_for_each_entry(as, &apm_user_list, list) {
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if (as->reader)
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queue_add_event(&as->queue, event);
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}
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up_read(&user_list_lock);
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wake_up_interruptible(&apm_waitqueue);
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}
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static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
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{
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struct apm_user *as = fp->private_data;
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apm_event_t event;
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int i = count, ret = 0;
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if (count < sizeof(apm_event_t))
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return -EINVAL;
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if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
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return -EAGAIN;
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wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
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while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
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event = queue_get_event(&as->queue);
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ret = -EFAULT;
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if (copy_to_user(buf, &event, sizeof(event)))
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break;
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mutex_lock(&state_lock);
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if (as->suspend_state == SUSPEND_PENDING &&
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(event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
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as->suspend_state = SUSPEND_READ;
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mutex_unlock(&state_lock);
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buf += sizeof(event);
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i -= sizeof(event);
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}
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if (i < count)
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ret = count - i;
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return ret;
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}
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static unsigned int apm_poll(struct file *fp, poll_table * wait)
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{
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struct apm_user *as = fp->private_data;
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poll_wait(fp, &apm_waitqueue, wait);
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return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
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}
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/*
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* apm_ioctl - handle APM ioctl
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*
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* APM_IOC_SUSPEND
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* This IOCTL is overloaded, and performs two functions. It is used to:
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* - initiate a suspend
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* - acknowledge a suspend read from /dev/apm_bios.
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* Only when everyone who has opened /dev/apm_bios with write permission
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* has acknowledge does the actual suspend happen.
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*/
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static long
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apm_ioctl(struct file *filp, u_int cmd, u_long arg)
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{
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struct apm_user *as = filp->private_data;
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int err = -EINVAL;
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if (!as->suser || !as->writer)
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return -EPERM;
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switch (cmd) {
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case APM_IOC_SUSPEND:
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mutex_lock(&state_lock);
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as->suspend_result = -EINTR;
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switch (as->suspend_state) {
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case SUSPEND_READ:
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/*
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* If we read a suspend command from /dev/apm_bios,
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* then the corresponding APM_IOC_SUSPEND ioctl is
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* interpreted as an acknowledge.
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*/
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as->suspend_state = SUSPEND_ACKED;
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atomic_dec(&suspend_acks_pending);
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mutex_unlock(&state_lock);
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/*
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* suspend_acks_pending changed, the notifier needs to
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* be woken up for this
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*/
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wake_up(&apm_suspend_waitqueue);
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/*
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* Wait for the suspend/resume to complete. If there
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* are pending acknowledges, we wait here for them.
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* wait_event_freezable() is interruptible and pending
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* signal can cause busy looping. We aren't doing
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* anything critical, chill a bit on each iteration.
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*/
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while (wait_event_freezable(apm_suspend_waitqueue,
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as->suspend_state != SUSPEND_ACKED))
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msleep(10);
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break;
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case SUSPEND_ACKTO:
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as->suspend_result = -ETIMEDOUT;
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mutex_unlock(&state_lock);
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break;
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default:
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as->suspend_state = SUSPEND_WAIT;
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mutex_unlock(&state_lock);
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/*
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* Otherwise it is a request to suspend the system.
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* Just invoke pm_suspend(), we'll handle it from
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* there via the notifier.
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*/
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as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
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}
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mutex_lock(&state_lock);
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err = as->suspend_result;
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as->suspend_state = SUSPEND_NONE;
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mutex_unlock(&state_lock);
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break;
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}
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return err;
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}
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static int apm_release(struct inode * inode, struct file * filp)
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{
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struct apm_user *as = filp->private_data;
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filp->private_data = NULL;
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down_write(&user_list_lock);
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list_del(&as->list);
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up_write(&user_list_lock);
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/*
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* We are now unhooked from the chain. As far as new
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* events are concerned, we no longer exist.
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*/
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mutex_lock(&state_lock);
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if (as->suspend_state == SUSPEND_PENDING ||
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as->suspend_state == SUSPEND_READ)
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atomic_dec(&suspend_acks_pending);
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mutex_unlock(&state_lock);
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wake_up(&apm_suspend_waitqueue);
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kfree(as);
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return 0;
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}
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static int apm_open(struct inode * inode, struct file * filp)
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{
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struct apm_user *as;
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as = kzalloc(sizeof(*as), GFP_KERNEL);
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if (as) {
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/*
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* XXX - this is a tiny bit broken, when we consider BSD
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* process accounting. If the device is opened by root, we
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* instantly flag that we used superuser privs. Who knows,
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* we might close the device immediately without doing a
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* privileged operation -- cevans
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*/
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as->suser = capable(CAP_SYS_ADMIN);
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as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
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as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
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down_write(&user_list_lock);
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list_add(&as->list, &apm_user_list);
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up_write(&user_list_lock);
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filp->private_data = as;
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}
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return as ? 0 : -ENOMEM;
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}
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static const struct file_operations apm_bios_fops = {
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.owner = THIS_MODULE,
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.read = apm_read,
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.poll = apm_poll,
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.unlocked_ioctl = apm_ioctl,
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.open = apm_open,
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.release = apm_release,
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.llseek = noop_llseek,
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};
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static struct miscdevice apm_device = {
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.minor = APM_MINOR_DEV,
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.name = "apm_bios",
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.fops = &apm_bios_fops
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};
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#ifdef CONFIG_PROC_FS
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/*
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* Arguments, with symbols from linux/apm_bios.h.
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*
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* 0) Linux driver version (this will change if format changes)
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* 1) APM BIOS Version. Usually 1.0, 1.1 or 1.2.
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* 2) APM flags from APM Installation Check (0x00):
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* bit 0: APM_16_BIT_SUPPORT
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* bit 1: APM_32_BIT_SUPPORT
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* bit 2: APM_IDLE_SLOWS_CLOCK
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* bit 3: APM_BIOS_DISABLED
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* bit 4: APM_BIOS_DISENGAGED
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* 3) AC line status
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* 0x00: Off-line
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* 0x01: On-line
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* 0x02: On backup power (BIOS >= 1.1 only)
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* 0xff: Unknown
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* 4) Battery status
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* 0x00: High
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* 0x01: Low
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* 0x02: Critical
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* 0x03: Charging
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* 0x04: Selected battery not present (BIOS >= 1.2 only)
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* 0xff: Unknown
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* 5) Battery flag
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* bit 0: High
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* bit 1: Low
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* bit 2: Critical
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* bit 3: Charging
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* bit 7: No system battery
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* 0xff: Unknown
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* 6) Remaining battery life (percentage of charge):
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* 0-100: valid
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* -1: Unknown
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* 7) Remaining battery life (time units):
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* Number of remaining minutes or seconds
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* -1: Unknown
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* 8) min = minutes; sec = seconds
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*/
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static int proc_apm_show(struct seq_file *m, void *v)
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{
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struct apm_power_info info;
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char *units;
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info.ac_line_status = 0xff;
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info.battery_status = 0xff;
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info.battery_flag = 0xff;
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info.battery_life = -1;
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info.time = -1;
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info.units = -1;
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if (apm_get_power_status)
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apm_get_power_status(&info);
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switch (info.units) {
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default: units = "?"; break;
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case 0: units = "min"; break;
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case 1: units = "sec"; break;
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}
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seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
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driver_version, APM_32_BIT_SUPPORT,
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info.ac_line_status, info.battery_status,
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info.battery_flag, info.battery_life,
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info.time, units);
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return 0;
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}
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static int proc_apm_open(struct inode *inode, struct file *file)
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{
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return single_open(file, proc_apm_show, NULL);
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}
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static const struct file_operations apm_proc_fops = {
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.owner = THIS_MODULE,
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.open = proc_apm_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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#endif
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static int kapmd(void *arg)
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{
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do {
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apm_event_t event;
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wait_event_interruptible(kapmd_wait,
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!queue_empty(&kapmd_queue) || kthread_should_stop());
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if (kthread_should_stop())
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break;
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spin_lock_irq(&kapmd_queue_lock);
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event = 0;
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if (!queue_empty(&kapmd_queue))
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event = queue_get_event(&kapmd_queue);
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spin_unlock_irq(&kapmd_queue_lock);
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|
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switch (event) {
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case 0:
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break;
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|
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case APM_LOW_BATTERY:
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case APM_POWER_STATUS_CHANGE:
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queue_event(event);
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break;
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|
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case APM_USER_SUSPEND:
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case APM_SYS_SUSPEND:
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pm_suspend(PM_SUSPEND_MEM);
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break;
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|
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case APM_CRITICAL_SUSPEND:
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atomic_inc(&userspace_notification_inhibit);
|
|
pm_suspend(PM_SUSPEND_MEM);
|
|
atomic_dec(&userspace_notification_inhibit);
|
|
break;
|
|
}
|
|
} while (1);
|
|
|
|
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 notifier_from_errno(err);
|
|
|
|
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;
|
|
|
|
if (apm_disabled) {
|
|
printk(KERN_NOTICE "apm: disabled on user request.\n");
|
|
return -ENODEV;
|
|
}
|
|
|
|
kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
|
|
if (IS_ERR(kapmd_tsk)) {
|
|
ret = PTR_ERR(kapmd_tsk);
|
|
kapmd_tsk = NULL;
|
|
goto out;
|
|
}
|
|
wake_up_process(kapmd_tsk);
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
proc_create("apm", 0, NULL, &apm_proc_fops);
|
|
#endif
|
|
|
|
ret = misc_register(&apm_device);
|
|
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);
|
|
|
|
kthread_stop(kapmd_tsk);
|
|
}
|
|
|
|
module_init(apm_init);
|
|
module_exit(apm_exit);
|
|
|
|
MODULE_AUTHOR("Stephen Rothwell");
|
|
MODULE_DESCRIPTION("Advanced Power Management");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
#ifndef MODULE
|
|
static int __init apm_setup(char *str)
|
|
{
|
|
while ((str != NULL) && (*str != '\0')) {
|
|
if (strncmp(str, "off", 3) == 0)
|
|
apm_disabled = 1;
|
|
if (strncmp(str, "on", 2) == 0)
|
|
apm_disabled = 0;
|
|
str = strchr(str, ',');
|
|
if (str != NULL)
|
|
str += strspn(str, ", \t");
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
__setup("apm=", apm_setup);
|
|
#endif
|
|
|
|
/**
|
|
* apm_queue_event - queue an APM event for kapmd
|
|
* @event: APM event
|
|
*
|
|
* Queue an APM event for kapmd to process and ultimately take the
|
|
* appropriate action. Only a subset of events are handled:
|
|
* %APM_LOW_BATTERY
|
|
* %APM_POWER_STATUS_CHANGE
|
|
* %APM_USER_SUSPEND
|
|
* %APM_SYS_SUSPEND
|
|
* %APM_CRITICAL_SUSPEND
|
|
*/
|
|
void apm_queue_event(apm_event_t event)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&kapmd_queue_lock, flags);
|
|
queue_add_event(&kapmd_queue, event);
|
|
spin_unlock_irqrestore(&kapmd_queue_lock, flags);
|
|
|
|
wake_up_interruptible(&kapmd_wait);
|
|
}
|
|
EXPORT_SYMBOL(apm_queue_event);
|