RTC: periodic irq fix

Add kernel/kernel and kernel/user locking for the periodic irq feature of
the rtc class.

PIE ioctls are also supported.

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 24 insertions, 25 deletions

diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index 10ab3b71ffc6..4dfdf019fccc 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -153,6 +153,7 @@ struct rtc_device *rtc_device_register(const char *name, struct device *dev,
         mutex_init(&rtc->ops_lock);
         spin_lock_init(&rtc->irq_lock);
         spin_lock_init(&rtc->irq_task_lock);
+        init_waitqueue_head(&rtc->irq_queue);
 
         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
         snprintf(rtc->dev.bus_id, BUS_ID_SIZE, "rtc%d", id);
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index ad66c6ecf365..a43afa54f0d7 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -210,6 +210,10 @@ int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
         if (task == NULL || task->func == NULL)
                 return -EINVAL;
 
+        /* Cannot register while the char dev is in use */
+        if (!(mutex_trylock(&rtc->char_lock)))
+                return -EBUSY;
+
         spin_lock_irq(&rtc->irq_task_lock);
         if (rtc->irq_task == NULL) {
                 rtc->irq_task = task;
@@ -217,13 +221,14 @@ int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
         }
         spin_unlock_irq(&rtc->irq_task_lock);
 
+        mutex_unlock(&rtc->char_lock);
+
         return retval;
 }
 EXPORT_SYMBOL_GPL(rtc_irq_register);
 
 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 {
-
         spin_lock_irq(&rtc->irq_task_lock);
         if (rtc->irq_task == task)
                 rtc->irq_task = NULL;
@@ -240,8 +245,10 @@ int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled
                 return -ENXIO;
 
         spin_lock_irqsave(&rtc->irq_task_lock, flags);
+        if (rtc->irq_task != NULL && task == NULL)
+                err = -EBUSY;
         if (rtc->irq_task != task)
-                err = -ENXIO;
+                err = -EACCES;
         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 
         if (err == 0)
@@ -260,8 +267,10 @@ int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
                 return -ENXIO;
 
         spin_lock_irqsave(&rtc->irq_task_lock, flags);
+        if (rtc->irq_task != NULL && task == NULL)
+                err = -EBUSY;
         if (rtc->irq_task != task)
-                err = -ENXIO;
+                err = -EACCES;
         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 
         if (err == 0) {
diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index 005fff3a3508..362400db2e8b 100644
--- a/drivers/rtc/rtc-dev.c
+++ b/drivers/rtc/rtc-dev.c
@@ -238,17 +238,6 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file,
                 break;
         }
 
-        /* avoid conflicting IRQ users */
-        if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
-                spin_lock_irq(&rtc->irq_task_lock);
-                if (rtc->irq_task)
-                        err = -EBUSY;
-                spin_unlock_irq(&rtc->irq_task_lock);
-
-                if (err < 0)
-                        return err;
-        }
-
         /* try the driver's ioctl interface */
         if (ops->ioctl) {
                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
@@ -338,18 +327,20 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file,
                 err = rtc_set_time(rtc, &tm);
                 break;
 
-        case RTC_IRQP_READ:
-                if (ops->irq_set_freq)
-                        err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
-                else
-                        err = -ENOTTY;
+        case RTC_PIE_ON:
+                err = rtc_irq_set_state(rtc, NULL, 1);
+                break;
+
+        case RTC_PIE_OFF:
+                err = rtc_irq_set_state(rtc, NULL, 0);
                 break;
 
         case RTC_IRQP_SET:
-                if (ops->irq_set_freq)
-                        err = rtc_irq_set_freq(rtc, rtc->irq_task, arg);
-                else
-                        err = -ENOTTY;
+                err = rtc_irq_set_freq(rtc, NULL, arg);
+                break;
+
+        case RTC_IRQP_READ:
+                err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
                 break;
 
 #if 0
@@ -449,8 +440,6 @@ void rtc_dev_prepare(struct rtc_device *rtc)
         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 
         mutex_init(&rtc->char_lock);
-        spin_lock_init(&rtc->irq_lock);
-        init_waitqueue_head(&rtc->irq_queue);
 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
         INIT_WORK(&rtc->uie_task, rtc_uie_task);
         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);