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staging:iio:events: Use waitqueue lock to protect event queue 

Use the waitqueue lock to protect the event queue instead of a custom mutex.
This has the advantage that we can call the waitqueue operations with the lock
held, which simplifies the code flow a bit.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Lars-Peter Clausen 2012-01-03 14:59:40 +01:00 committed by Greg Kroah-Hartman
parent 2c00193fa1
commit 43ba1100af
1 changed files with 18 additions and 25 deletions
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43
drivers/staging/iio/industrialio-event.c
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@ -35,7 +35,6 @@
*/
struct iio_event_interface {
wait_queue_head_t wait;
struct mutex event_list_lock;
DECLARE_KFIFO(det_events, struct iio_event_data, 16);
struct list_head dev_attr_list;
@ -50,19 +49,17 @@ int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
int copied;
/* Does anyone care? */
mutex_lock(&ev_int->event_list_lock);
spin_lock(&ev_int->wait.lock);
if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
ev.id = ev_code;
ev.timestamp = timestamp;
copied = kfifo_put(&ev_int->det_events, &ev);
mutex_unlock(&ev_int->event_list_lock);
if (copied != 0)
wake_up_interruptible(&ev_int->wait);
} else
mutex_unlock(&ev_int->event_list_lock);
wake_up_locked(&ev_int->wait);
}
spin_unlock(&ev_int->wait.lock);
return 0;
}
@ -80,28 +77,25 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
if (count < sizeof(struct iio_event_data))
return -EINVAL;
mutex_lock(&ev_int->event_list_lock);
spin_lock(&ev_int->wait.lock);
if (kfifo_is_empty(&ev_int->det_events)) {
if (filep->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
goto error_mutex_unlock;
goto error_unlock;
}
mutex_unlock(&ev_int->event_list_lock);
/* Blocking on device; waiting for something to be there */
ret = wait_event_interruptible(ev_int->wait,
ret = wait_event_interruptible_locked(ev_int->wait,
!kfifo_is_empty(&ev_int->det_events));
if (ret)
goto error_ret;
goto error_unlock;
/* Single access device so no one else can get the data */
mutex_lock(&ev_int->event_list_lock);
}
mutex_unlock(&ev_int->event_list_lock);
ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
error_mutex_unlock:
mutex_unlock(&ev_int->event_list_lock);
error_ret:
error_unlock:
spin_unlock(&ev_int->wait.lock);
return ret ? ret : copied;
}
@ -109,7 +103,7 @@ static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
{
struct iio_event_interface *ev_int = filep->private_data;
mutex_lock(&ev_int->event_list_lock);
spin_lock(&ev_int->wait.lock);
clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
/*
* In order to maintain a clean state for reopening,
@ -117,7 +111,7 @@ static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
* any new __iio_push_event calls running.
*/
kfifo_reset_out(&ev_int->det_events);
mutex_unlock(&ev_int->event_list_lock);
spin_unlock(&ev_int->wait.lock);
return 0;
}
@ -137,18 +131,18 @@ int iio_event_getfd(struct iio_dev *indio_dev)
if (ev_int == NULL)
return -ENODEV;
mutex_lock(&ev_int->event_list_lock);
spin_lock(&ev_int->wait.lock);
if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
mutex_unlock(&ev_int->event_list_lock);
spin_unlock(&ev_int->wait.lock);
return -EBUSY;
}
mutex_unlock(&ev_int->event_list_lock);
spin_unlock(&ev_int->wait.lock);
fd = anon_inode_getfd("iio:event",
&iio_event_chrdev_fileops, ev_int, O_RDONLY);
if (fd < 0) {
mutex_lock(&ev_int->event_list_lock);
spin_lock(&ev_int->wait.lock);
clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
mutex_unlock(&ev_int->event_list_lock);
spin_unlock(&ev_int->wait.lock);
}
return fd;
}
@ -360,7 +354,6 @@ static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
static void iio_setup_ev_int(struct iio_event_interface *ev_int)
{
mutex_init(&ev_int->event_list_lock);
INIT_KFIFO(ev_int->det_events);
init_waitqueue_head(&ev_int->wait);
}