diff mbox series

[v3,01/12] media: staging: rkisp1: params: upon stream stop, iterate a local list to return the buffers

Message ID 20200922113402.12442-2-dafna.hirschfeld@collabora.com
State Accepted
Commit b1b2715e8d616bab68ed4e22b6617601105f2947
Headers show
Series [v3,01/12] media: staging: rkisp1: params: upon stream stop, iterate a local list to return the buffers | expand

Commit Message

Dafna Hirschfeld Sept. 22, 2020, 11:33 a.m. UTC 
The code in '.stop_streaming' callback releases and acquire the lock
at each iteration when returning the buffers.
Holding the lock disables interrupts so it should be minimized.
To make the code cleaner and still minimize holding the lock,
the buffer list is first moved to a local list and
then can be iterated without the lock.

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Acked-by: Helen Koike <helen.koike@collabora.com>
---
 drivers/staging/media/rkisp1/rkisp1-params.c | 31 +++++++-------------
 1 file changed, 11 insertions(+), 20 deletions(-)

Comments

Tomasz Figa Sept. 25, 2020, 7:08 p.m. UTC | #1 
Hi Dafna,

On Tue, Sep 22, 2020 at 01:33:51PM +0200, Dafna Hirschfeld wrote:
> The code in '.stop_streaming' callback releases and acquire the lock
> at each iteration when returning the buffers.
> Holding the lock disables interrupts so it should be minimized.
> To make the code cleaner and still minimize holding the lock,
> the buffer list is first moved to a local list and
> then can be iterated without the lock.
> 
> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
> Acked-by: Helen Koike <helen.koike@collabora.com>
> ---
>  drivers/staging/media/rkisp1/rkisp1-params.c | 31 +++++++-------------
>  1 file changed, 11 insertions(+), 20 deletions(-)
> 

Thank you for the patch. Please see my comments inline.

> diff --git a/drivers/staging/media/rkisp1/rkisp1-params.c b/drivers/staging/media/rkisp1/rkisp1-params.c
> index 3ca2afc51ead..85f3b340c3bf 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-params.c
> +++ b/drivers/staging/media/rkisp1/rkisp1-params.c
> @@ -1469,32 +1469,23 @@ static void rkisp1_params_vb2_stop_streaming(struct vb2_queue *vq)
>  {
>  	struct rkisp1_params *params = vq->drv_priv;
>  	struct rkisp1_buffer *buf;
> +	struct list_head tmp_list;
>  	unsigned long flags;
> -	unsigned int i;
>  
> -	/* stop params input firstly */
> +	INIT_LIST_HEAD(&tmp_list);

nit: This could be done at declaration time by using the LIST_HEAD()
macro to declare the list head.

> +
> +	/*
> +	 * we first move the buffers into a local list 'tmp_list'
> +	 * and then we can iterate it and call vb2_buffer_done
> +	 * without holding the lock
> +	 */
>  	spin_lock_irqsave(&params->config_lock, flags);
>  	params->is_streaming = false;
> +	list_cut_position(&tmp_list, &params->params, params->params.prev);

nit: This is equivalent to list_splice_init(&params->params, &tmp_list);
with a simpler interface and without the need to dereference
params->params.prev manually.

Best regards,
Tomasz
diff mbox series

Patch

diff --git a/drivers/staging/media/rkisp1/rkisp1-params.c b/drivers/staging/media/rkisp1/rkisp1-params.c
index 3ca2afc51ead..85f3b340c3bf 100644
--- a/drivers/staging/media/rkisp1/rkisp1-params.c
+++ b/drivers/staging/media/rkisp1/rkisp1-params.c
@@ -1469,32 +1469,23 @@  static void rkisp1_params_vb2_stop_streaming(struct vb2_queue *vq)
 {
 	struct rkisp1_params *params = vq->drv_priv;
 	struct rkisp1_buffer *buf;
+	struct list_head tmp_list;
 	unsigned long flags;
-	unsigned int i;
 
-	/* stop params input firstly */
+	INIT_LIST_HEAD(&tmp_list);
+
+	/*
+	 * we first move the buffers into a local list 'tmp_list'
+	 * and then we can iterate it and call vb2_buffer_done
+	 * without holding the lock
+	 */
 	spin_lock_irqsave(&params->config_lock, flags);
 	params->is_streaming = false;
+	list_cut_position(&tmp_list, &params->params, params->params.prev);
 	spin_unlock_irqrestore(&params->config_lock, flags);
 
-	for (i = 0; i < RKISP1_ISP_PARAMS_REQ_BUFS_MAX; i++) {
-		spin_lock_irqsave(&params->config_lock, flags);
-		if (!list_empty(&params->params)) {
-			buf = list_first_entry(&params->params,
-					       struct rkisp1_buffer, queue);
-			list_del(&buf->queue);
-			spin_unlock_irqrestore(&params->config_lock,
-					       flags);
-		} else {
-			spin_unlock_irqrestore(&params->config_lock,
-					       flags);
-			break;
-		}
-
-		if (buf)
-			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
-		buf = NULL;
-	}
+	list_for_each_entry(buf, &tmp_list, queue)
+		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
 }
 
 static int