The current IIO event code uses a list to emulate FIFO like behavior.
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 | 85 +++++++----------------------
1 files changed, 21 insertions(+), 64 deletions(-)
diff --git a/drivers/staging/iio/industrialio-event.c b/drivers/staging/iio/industrialio-event.c
index a7b345d..335b615 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;
@@ -401,10 +361,7 @@ 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);
}
--
1.7.8.3
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