On 12/19/2011 10:29 AM, Lars-Peter Clausen wrote:
> The current IIO event code uses a list to emulate FIFO like behaviour.
> Just use a kfifo directly instead to implement the event queue. As part of this
> patch the maximum of events in the queue is increased from 10 to 16 since kfifo
> requires a power of two for the number of fifo elements.
>
> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Acked-by: Jonathan Cameron <jic23@xxxxxxxxxx>
> ---
> drivers/staging/iio/industrialio-event.c | 88 +++++++-----------------------
> 1 files changed, 21 insertions(+), 67 deletions(-)
>
> diff --git a/drivers/staging/iio/industrialio-event.c b/drivers/staging/iio/industrialio-event.c
> index a7b345d..d63aa0b 100644
> --- a/drivers/staging/iio/industrialio-event.c
> +++ b/drivers/staging/iio/industrialio-event.c
> @@ -13,6 +13,7 @@
> #include <linux/device.h>
> #include <linux/fs.h>
> #include <linux/kernel.h>
> +#include <linux/kfifo.h>
> #include <linux/module.h>
> #include <linux/sched.h>
> #include <linux/slab.h>
> @@ -24,22 +25,10 @@
> #include "events.h"
>
> /**
> - * struct iio_detected_event_list - list element for events that have occurred
> - * @list: linked list header
> - * @ev: the event itself
> - */
> -struct iio_detected_event_list {
> - struct list_head list;
> - struct iio_event_data ev;
> -};
> -
> -/**
> * struct iio_event_interface - chrdev interface for an event line
> * @wait: wait queue to allow blocking reads of events
> * @event_list_lock: mutex to protect the list of detected events
> * @det_events: list of detected events
> - * @max_events: maximum number of events before new ones are dropped
> - * @current_events: number of events in detected list
> * @dev_attr_list: list of event interface sysfs attribute
> * @flags: file operations related flags including busy flag.
> * @group: event interface sysfs attribute group
> @@ -47,9 +36,8 @@ struct iio_detected_event_list {
> struct iio_event_interface {
> wait_queue_head_t wait;
> struct mutex event_list_lock;
> - struct list_head det_events;
> - int max_events;
> - int current_events;
> + DECLARE_KFIFO(det_events, struct iio_event_data, 16);
> +
> struct list_head dev_attr_list;
> unsigned long flags;
> struct attribute_group group;
> @@ -58,34 +46,25 @@ struct iio_event_interface {
> int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
> {
> struct iio_event_interface *ev_int = indio_dev->event_interface;
> - struct iio_detected_event_list *ev;
> - int ret = 0;
> + struct iio_event_data ev;
> + int copied;
>
> /* Does anyone care? */
> mutex_lock(&ev_int->event_list_lock);
> if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
> - if (ev_int->current_events == ev_int->max_events) {
> - mutex_unlock(&ev_int->event_list_lock);
> - return 0;
> - }
> - ev = kmalloc(sizeof(*ev), GFP_KERNEL);
> - if (ev == NULL) {
> - ret = -ENOMEM;
> - mutex_unlock(&ev_int->event_list_lock);
> - goto error_ret;
> - }
> - ev->ev.id = ev_code;
> - ev->ev.timestamp = timestamp;
>
> - list_add_tail(&ev->list, &ev_int->det_events);
> - ev_int->current_events++;
> + ev.id = ev_code;
> + ev.timestamp = timestamp;
> +
> + copied = kfifo_put(&ev_int->det_events, &ev);
> +
> mutex_unlock(&ev_int->event_list_lock);
> - wake_up_interruptible(&ev_int->wait);
> + if (copied != 0)
> + wake_up_interruptible(&ev_int->wait);
> } else
> mutex_unlock(&ev_int->event_list_lock);
>
> -error_ret:
> - return ret;
> + return 0;
> }
> EXPORT_SYMBOL(iio_push_event);
>
> @@ -95,15 +74,14 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
> loff_t *f_ps)
> {
> struct iio_event_interface *ev_int = filep->private_data;
> - struct iio_detected_event_list *el;
> - size_t len = sizeof(el->ev);
> + unsigned int copied;
> int ret;
>
> - if (count < len)
> + if (count < sizeof(struct iio_event_data))
> return -EINVAL;
>
> mutex_lock(&ev_int->event_list_lock);
> - if (list_empty(&ev_int->det_events)) {
> + if (kfifo_is_empty(&ev_int->det_events)) {
> if (filep->f_flags & O_NONBLOCK) {
> ret = -EAGAIN;
> goto error_mutex_unlock;
> @@ -111,39 +89,25 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
> mutex_unlock(&ev_int->event_list_lock);
> /* Blocking on device; waiting for something to be there */
> ret = wait_event_interruptible(ev_int->wait,
> - !list_empty(&ev_int
> - ->det_events));
> + !kfifo_is_empty(&ev_int->det_events));
> if (ret)
> goto error_ret;
> /* Single access device so no one else can get the data */
> mutex_lock(&ev_int->event_list_lock);
> }
>
> - el = list_first_entry(&ev_int->det_events,
> - struct iio_detected_event_list,
> - list);
> - if (copy_to_user(buf, &(el->ev), len)) {
> - ret = -EFAULT;
> - goto error_mutex_unlock;
> - }
> - list_del(&el->list);
> - ev_int->current_events--;
> mutex_unlock(&ev_int->event_list_lock);
> - kfree(el);
> -
> - return len;
> + ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
>
> error_mutex_unlock:
> mutex_unlock(&ev_int->event_list_lock);
> error_ret:
> -
> - return ret;
> + return ret ? ret : copied;
> }
>
> static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
> {
> struct iio_event_interface *ev_int = filep->private_data;
> - struct iio_detected_event_list *el, *t;
>
> mutex_lock(&ev_int->event_list_lock);
> clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
> @@ -152,11 +116,7 @@ static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
> * clear out any awaiting events. The mask will prevent
> * any new __iio_push_event calls running.
> */
> - list_for_each_entry_safe(el, t, &ev_int->det_events, list) {
> - list_del(&el->list);
> - kfree(el);
> - }
> - ev_int->current_events = 0;
> + kfifo_reset_out(&ev_int->det_events);
> mutex_unlock(&ev_int->event_list_lock);
>
> return 0;
> @@ -268,9 +228,6 @@ static ssize_t iio_ev_value_store(struct device *dev,
> unsigned long val;
> int ret;
>
> - if (!indio_dev->info->write_event_value)
> - return -EINVAL;
> -
> ret = strict_strtoul(buf, 10, &val);
> if (ret)
> return ret;
> @@ -401,10 +358,7 @@ 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);
> - /* discussion point - make this variable? */
> - ev_int->max_events = 10;
> - ev_int->current_events = 0;
> - INIT_LIST_HEAD(&ev_int->det_events);
> + INIT_KFIFO(ev_int->det_events);
> init_waitqueue_head(&ev_int->wait);
> }
>
--
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