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staging:iio:events: Use kfifo for event queue 

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@metafoo.de>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lars-Peter Clausen 2012-01-03 14:59:39 +01:00 committed by Greg Kroah-Hartman
parent 0a769a9533
commit 2c00193fa1
1 changed files with 21 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

85
drivers/staging/iio/industrialio-event.c
View File

@ -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>
@ -23,23 +24,11 @@
#include "sysfs.h"
#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);
}