iio:buffer: Simplify iio_buffer_is_active()

We can skip having to loop through all the device's buffers to see if a certain
buffer is active, if we let the buffer's list head point to itself when the
buffer is inactive.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index e73033f..96e97ad 100644 (file)
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -31,16 +31,9 @@ static const char * const iio_endian_prefix[] = {
        [IIO_LE] = "le",
 };
 
-static bool iio_buffer_is_active(struct iio_dev *indio_dev,
-                                struct iio_buffer *buf)
+static bool iio_buffer_is_active(struct iio_buffer *buf)
 {
-       struct list_head *p;
-
-       list_for_each(p, &indio_dev->buffer_list)
-               if (p == &buf->buffer_list)
-                       return true;
-
-       return false;
+       return !list_empty(&buf->buffer_list);
 }
 
 /**
@@ -79,6 +72,7 @@ unsigned int iio_buffer_poll(struct file *filp,
 void iio_buffer_init(struct iio_buffer *buffer)
 {
        INIT_LIST_HEAD(&buffer->demux_list);
+       INIT_LIST_HEAD(&buffer->buffer_list);
        init_waitqueue_head(&buffer->pollq);
 }
 EXPORT_SYMBOL(iio_buffer_init);
@@ -146,7 +140,7 @@ static ssize_t iio_scan_el_store(struct device *dev,
        if (ret < 0)
                return ret;
        mutex_lock(&indio_dev->mlock);
-       if (iio_buffer_is_active(indio_dev, indio_dev->buffer)) {
+       if (iio_buffer_is_active(indio_dev->buffer)) {
                ret = -EBUSY;
                goto error_ret;
        }
@@ -192,7 +186,7 @@ static ssize_t iio_scan_el_ts_store(struct device *dev,
                return ret;
 
        mutex_lock(&indio_dev->mlock);
-       if (iio_buffer_is_active(indio_dev, indio_dev->buffer)) {
+       if (iio_buffer_is_active(indio_dev->buffer)) {
                ret = -EBUSY;
                goto error_ret;
        }
@@ -396,7 +390,7 @@ ssize_t iio_buffer_write_length(struct device *dev,
                        return len;
 
        mutex_lock(&indio_dev->mlock);
-       if (iio_buffer_is_active(indio_dev, indio_dev->buffer)) {
+       if (iio_buffer_is_active(indio_dev->buffer)) {
                ret = -EBUSY;
        } else {
                if (buffer->access->set_length)
@@ -414,9 +408,7 @@ ssize_t iio_buffer_show_enable(struct device *dev,
                               char *buf)
 {
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-       return sprintf(buf, "%d\n",
-                      iio_buffer_is_active(indio_dev,
-                                           indio_dev->buffer));
+       return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
 }
 EXPORT_SYMBOL(iio_buffer_show_enable);
 
@@ -490,7 +482,7 @@ int iio_update_buffers(struct iio_dev *indio_dev,
                indio_dev->active_scan_mask = NULL;
 
        if (remove_buffer)
-               list_del(&remove_buffer->buffer_list);
+               list_del_init(&remove_buffer->buffer_list);
        if (insert_buffer)
                list_add(&insert_buffer->buffer_list, &indio_dev->buffer_list);
 
@@ -527,7 +519,7 @@ int iio_update_buffers(struct iio_dev *indio_dev,
                         * Roll back.
                         * Note can only occur when adding a buffer.
                         */
-                       list_del(&insert_buffer->buffer_list);
+                       list_del_init(&insert_buffer->buffer_list);
                        indio_dev->active_scan_mask = old_mask;
                        success = -EINVAL;
                }
@@ -611,7 +603,7 @@ error_run_postdisable:
 error_remove_inserted:
 
        if (insert_buffer)
-               list_del(&insert_buffer->buffer_list);
+               list_del_init(&insert_buffer->buffer_list);
        indio_dev->active_scan_mask = old_mask;
        kfree(compound_mask);
 error_ret:
@@ -628,7 +620,6 @@ ssize_t iio_buffer_store_enable(struct device *dev,
        int ret;
        bool requested_state;
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-       struct iio_buffer *pbuf = indio_dev->buffer;
        bool inlist;
 
        ret = strtobool(buf, &requested_state);
@@ -638,7 +629,7 @@ ssize_t iio_buffer_store_enable(struct device *dev,
        mutex_lock(&indio_dev->mlock);
 
        /* Find out if it is in the list */
-       inlist = iio_buffer_is_active(indio_dev, pbuf);
+       inlist = iio_buffer_is_active(indio_dev->buffer);
        /* Already in desired state */
        if (inlist == requested_state)
                goto done;