1 files changed, 131 insertions, 56 deletions

diff --git a/arch/arm/kernel/apm.c b/arch/arm/kernel/apm.c
index ecf4f9472d94..a11fb9a40c04 100644
--- a/arch/arm/kernel/apm.c
+++ b/arch/arm/kernel/apm.c
@@ -12,7 +12,6 @@
  */
 #include <linux/module.h>
 #include <linux/poll.h>
-#include <linux/timer.h>
 #include <linux/slab.h>
 #include <linux/proc_fs.h>
 #include <linux/miscdevice.h>
@@ -26,6 +25,7 @@
 #include <linux/init.h>
 #include <linux/completion.h>
 #include <linux/kthread.h>
+#include <linux/delay.h>
 
 #include <asm/apm.h> /* apm_power_info */
 #include <asm/system.h>
@@ -71,7 +71,8 @@ struct apm_user {
 #define SUSPEND_PENDING 1               /* suspend pending read */
 #define SUSPEND_READ    2               /* suspend read, pending ack */
 #define SUSPEND_ACKED   3               /* suspend acked */
-#define SUSPEND_DONE    4               /* suspend completed */
+#define SUSPEND_WAIT    4               /* waiting for suspend */
+#define SUSPEND_DONE    5               /* suspend completed */
 
         struct apm_queue        queue;
 };
@@ -101,6 +102,7 @@ static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
 static DEFINE_SPINLOCK(kapmd_queue_lock);
 static struct apm_queue kapmd_queue;
 
+static DEFINE_MUTEX(state_lock);
 
 static const char driver_version[] = "1.13";    /* no spaces */
 
@@ -148,38 +150,60 @@ static void queue_add_event(struct apm_queue *q, apm_event_t event)
         q->events[q->event_head] = event;
 }
 
-static void queue_event_one_user(struct apm_user *as, apm_event_t event)
+static void queue_event(apm_event_t event)
 {
-        if (as->suser && as->writer) {
-                switch (event) {
-                case APM_SYS_SUSPEND:
-                case APM_USER_SUSPEND:
-                        /*
-                         * If this user already has a suspend pending,
-                         * don't queue another one.
-                         */
-                        if (as->suspend_state != SUSPEND_NONE)
-                                return;
+        struct apm_user *as;
 
-                        as->suspend_state = SUSPEND_PENDING;
-                        suspends_pending++;
-                        break;
-                }
+        down_read(&user_list_lock);
+        list_for_each_entry(as, &apm_user_list, list) {
+                if (as->reader)
+                        queue_add_event(&as->queue, event);
         }
-        queue_add_event(&as->queue, event);
+        up_read(&user_list_lock);
+        wake_up_interruptible(&apm_waitqueue);
 }
 
-static void queue_event(apm_event_t event, struct apm_user *sender)
+/*
+ * 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)
-                        queue_event_one_user(as, event);
+                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)
@@ -191,17 +215,22 @@ static void apm_suspend(void)
          * 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, NULL);
+        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) {
-                as->suspend_result = err;
-                as->suspend_state = SUSPEND_DONE;
+                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);
 }
@@ -227,8 +256,11 @@ static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t
                 if (copy_to_user(buf, &event, sizeof(event)))
                         break;
 
-                if (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND)
+                mutex_lock(&state_lock);
+                if (as->suspend_state == SUSPEND_PENDING &&
+                    (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
                         as->suspend_state = SUSPEND_READ;
+                mutex_unlock(&state_lock);
 
                 buf += sizeof(event);
                 i -= sizeof(event);
@@ -270,9 +302,13 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
 
         switch (cmd) {
         case APM_IOC_SUSPEND:
+                mutex_lock(&state_lock);
+
                 as->suspend_result = -EINTR;
 
                 if (as->suspend_state == SUSPEND_READ) {
+                        int pending;
+
                         /*
                          * If we read a suspend command from /dev/apm_bios,
                          * then the corresponding APM_IOC_SUSPEND ioctl is
@@ -280,47 +316,73 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
                          */
                         as->suspend_state = SUSPEND_ACKED;
                         suspends_pending--;
+                        pending = suspends_pending == 0;
+                        mutex_unlock(&state_lock);
+
+                        /*
+                         * If there are no further acknowledges required,
+                         * suspend the system.
+                         */
+                        if (pending)
+                                apm_suspend();
+
+                        /*
+                         * Wait for the suspend/resume to complete.  If there
+                         * are pending acknowledges, we wait here for them.
+                         *
+                         * Note: we need to ensure that the PM subsystem does
+                         * not kick us out of the wait when it suspends the
+                         * threads.
+                         */
+                        flags = current->flags;
+                        current->flags |= PF_NOFREEZE;
+
+                        wait_event(apm_suspend_waitqueue,
+                                   as->suspend_state == SUSPEND_DONE);
                 } else {
+                        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.
                          */
-                        queue_event(APM_USER_SUSPEND, as);
-                }
-
-                /*
-                 * If there are no further acknowledges required, suspend
-                 * the system.
-                 */
-                if (suspends_pending == 0)
-                        apm_suspend();
+                        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.
-                 *
-                 * Note that we need to ensure that the PM subsystem does
-                 * not kick us out of the wait when it suspends the threads.
-                 */
-                flags = current->flags;
-                current->flags |= PF_NOFREEZE;
+                        /*
+                         * Wait for the suspend/resume to complete.  If there
+                         * are pending acknowledges, we wait here for them.
+                         *
+                         * Note: we need to ensure that the PM subsystem does
+                         * not kick us out of the wait when it suspends the
+                         * threads.
+                         */
+                        flags = current->flags;
+                        current->flags |= PF_NOFREEZE;
 
-                /*
-                 * Note: do not allow a thread which is acking the suspend
-                 * to escape until the resume is complete.
-                 */
-                if (as->suspend_state == SUSPEND_ACKED)
-                        wait_event(apm_suspend_waitqueue,
-                                         as->suspend_state == SUSPEND_DONE);
-                else
                         wait_event_interruptible(apm_suspend_waitqueue,
                                          as->suspend_state == SUSPEND_DONE);
+                }
 
                 current->flags = flags;
+
+                mutex_lock(&state_lock);
                 err = as->suspend_result;
                 as->suspend_state = SUSPEND_NONE;
+                mutex_unlock(&state_lock);
                 break;
         }
 
@@ -330,6 +392,8 @@ 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;
 
         down_write(&user_list_lock);
@@ -342,11 +406,14 @@ static int apm_release(struct inode * inode, struct file * filp)
          * need to balance suspends_pending, which means the
          * possibility of sleeping.
          */
+        mutex_lock(&state_lock);
         if (as->suspend_state != SUSPEND_NONE) {
                 suspends_pending -= 1;
-                if (suspends_pending == 0)
-                        apm_suspend();
+                pending = suspends_pending == 0;
         }
+        mutex_unlock(&state_lock);
+        if (pending)
+                apm_suspend();
 
         kfree(as);
         return 0;
@@ -470,6 +537,7 @@ static int kapmd(void *arg)
 {
         do {
                 apm_event_t event;
+                int ret;
 
                 wait_event_interruptible(kapmd_wait,
                                 !queue_empty(&kapmd_queue) || kthread_should_stop());
@@ -489,13 +557,20 @@ static int kapmd(void *arg)
 
                 case APM_LOW_BATTERY:
                 case APM_POWER_STATUS_CHANGE:
-                        queue_event(event, NULL);
+                        queue_event(event);
                         break;
 
                 case APM_USER_SUSPEND:
                 case APM_SYS_SUSPEND:
-                        queue_event(event, NULL);
-                        if (suspends_pending == 0)
+                        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();
                         break;