Commit 2c00193f authored by Lars-Peter Clausen's avatar Lars-Peter Clausen Committed by Greg Kroah-Hartman

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: default avatarLars-Peter Clausen <lars@metafoo.de>
Acked-by: default avatarJonathan Cameron <jic23@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0a769a95
...@@ -13,6 +13,7 @@ ...@@ -13,6 +13,7 @@
#include <linux/device.h> #include <linux/device.h>
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/kfifo.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/sched.h> #include <linux/sched.h>
#include <linux/slab.h> #include <linux/slab.h>
...@@ -23,23 +24,11 @@ ...@@ -23,23 +24,11 @@
#include "sysfs.h" #include "sysfs.h"
#include "events.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 * struct iio_event_interface - chrdev interface for an event line
* @wait: wait queue to allow blocking reads of events * @wait: wait queue to allow blocking reads of events
* @event_list_lock: mutex to protect the list of detected events * @event_list_lock: mutex to protect the list of detected events
* @det_events: 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 * @dev_attr_list: list of event interface sysfs attribute
* @flags: file operations related flags including busy flag. * @flags: file operations related flags including busy flag.
* @group: event interface sysfs attribute group * @group: event interface sysfs attribute group
...@@ -47,9 +36,8 @@ struct iio_detected_event_list { ...@@ -47,9 +36,8 @@ struct iio_detected_event_list {
struct iio_event_interface { struct iio_event_interface {
wait_queue_head_t wait; wait_queue_head_t wait;
struct mutex event_list_lock; struct mutex event_list_lock;
struct list_head det_events; DECLARE_KFIFO(det_events, struct iio_event_data, 16);
int max_events;
int current_events;
struct list_head dev_attr_list; struct list_head dev_attr_list;
unsigned long flags; unsigned long flags;
struct attribute_group group; struct attribute_group group;
...@@ -58,34 +46,25 @@ struct iio_event_interface { ...@@ -58,34 +46,25 @@ struct iio_event_interface {
int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp) 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_event_interface *ev_int = indio_dev->event_interface;
struct iio_detected_event_list *ev; struct iio_event_data ev;
int ret = 0; int copied;
/* Does anyone care? */ /* Does anyone care? */
mutex_lock(&ev_int->event_list_lock); mutex_lock(&ev_int->event_list_lock);
if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) { 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.id = ev_code;
ev_int->current_events++; ev.timestamp = timestamp;
copied = kfifo_put(&ev_int->det_events, &ev);
mutex_unlock(&ev_int->event_list_lock); mutex_unlock(&ev_int->event_list_lock);
if (copied != 0)
wake_up_interruptible(&ev_int->wait); wake_up_interruptible(&ev_int->wait);
} else } else
mutex_unlock(&ev_int->event_list_lock); mutex_unlock(&ev_int->event_list_lock);
error_ret: return 0;
return ret;
} }
EXPORT_SYMBOL(iio_push_event); EXPORT_SYMBOL(iio_push_event);
...@@ -95,15 +74,14 @@ static ssize_t iio_event_chrdev_read(struct file *filep, ...@@ -95,15 +74,14 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
loff_t *f_ps) loff_t *f_ps)
{ {
struct iio_event_interface *ev_int = filep->private_data; struct iio_event_interface *ev_int = filep->private_data;
struct iio_detected_event_list *el; unsigned int copied;
size_t len = sizeof(el->ev);
int ret; int ret;
if (count < len) if (count < sizeof(struct iio_event_data))
return -EINVAL; return -EINVAL;
mutex_lock(&ev_int->event_list_lock); 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) { if (filep->f_flags & O_NONBLOCK) {
ret = -EAGAIN; ret = -EAGAIN;
goto error_mutex_unlock; goto error_mutex_unlock;
...@@ -111,39 +89,25 @@ static ssize_t iio_event_chrdev_read(struct file *filep, ...@@ -111,39 +89,25 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
mutex_unlock(&ev_int->event_list_lock); mutex_unlock(&ev_int->event_list_lock);
/* Blocking on device; waiting for something to be there */ /* Blocking on device; waiting for something to be there */
ret = wait_event_interruptible(ev_int->wait, ret = wait_event_interruptible(ev_int->wait,
!list_empty(&ev_int !kfifo_is_empty(&ev_int->det_events));
->det_events));
if (ret) if (ret)
goto error_ret; goto error_ret;
/* Single access device so no one else can get the data */ /* Single access device so no one else can get the data */
mutex_lock(&ev_int->event_list_lock); 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); mutex_unlock(&ev_int->event_list_lock);
kfree(el); ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
return len;
error_mutex_unlock: error_mutex_unlock:
mutex_unlock(&ev_int->event_list_lock); mutex_unlock(&ev_int->event_list_lock);
error_ret: error_ret:
return ret ? ret : copied;
return ret;
} }
static int iio_event_chrdev_release(struct inode *inode, struct file *filep) static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
{ {
struct iio_event_interface *ev_int = filep->private_data; struct iio_event_interface *ev_int = filep->private_data;
struct iio_detected_event_list *el, *t;
mutex_lock(&ev_int->event_list_lock); mutex_lock(&ev_int->event_list_lock);
clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags); 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) ...@@ -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 * clear out any awaiting events. The mask will prevent
* any new __iio_push_event calls running. * any new __iio_push_event calls running.
*/ */
list_for_each_entry_safe(el, t, &ev_int->det_events, list) { kfifo_reset_out(&ev_int->det_events);
list_del(&el->list);
kfree(el);
}
ev_int->current_events = 0;
mutex_unlock(&ev_int->event_list_lock); mutex_unlock(&ev_int->event_list_lock);
return 0; return 0;
...@@ -401,10 +361,7 @@ static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev) ...@@ -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) static void iio_setup_ev_int(struct iio_event_interface *ev_int)
{ {
mutex_init(&ev_int->event_list_lock); mutex_init(&ev_int->event_list_lock);
/* discussion point - make this variable? */ INIT_KFIFO(ev_int->det_events);
ev_int->max_events = 10;
ev_int->current_events = 0;
INIT_LIST_HEAD(&ev_int->det_events);
init_waitqueue_head(&ev_int->wait); init_waitqueue_head(&ev_int->wait);
} }
......
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