From 2c00193fa15dc51566dc7931fe32184c99c6b317 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Tue, 3 Jan 2012 14:59:39 +0100 Subject: [PATCH] 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 Acked-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/staging/iio/industrialio-event.c | 85 ++++++++------------------------ 1 file 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 #include #include +#include #include #include #include @@ -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); } -- 2.7.4