Re: [PATCH 3/3] media: staging: rkisp1: params: in 'stop_streaming' don't release the lock while returning buffers

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Hi Dafna,

On 2020-06-25 18:42, Dafna Hirschfeld wrote:
In the stop_streaming callback 'rkisp1_params_vb2_stop_streaming'
there is no need to release the lock 'config_lock' and then acquire
it again at each iteration when returning all buffers.
This is because the stream is about to end and there is no need
to let the isr access a buffer.

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@xxxxxxxxxxxxx>
---
  drivers/staging/media/rkisp1/rkisp1-params.c | 7 +------
  1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/staging/media/rkisp1/rkisp1-params.c b/drivers/staging/media/rkisp1/rkisp1-params.c
index bf006dbeee2d..5169b02731f1 100644
--- a/drivers/staging/media/rkisp1/rkisp1-params.c
+++ b/drivers/staging/media/rkisp1/rkisp1-params.c
@@ -1488,19 +1488,13 @@ static void rkisp1_params_vb2_stop_streaming(struct vb2_queue *vq)
  	/* stop params input firstly */
  	spin_lock_irqsave(&params->config_lock, flags);
  	params->is_streaming = false;
-	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;
  		}

Just skimming through out of idle curiosity I was going to comment that if you end up with this pattern:

	if (!x) {
		//do stuff
	} else {
		break;
	}

it would be better as:

	if (x)
		break;
	//do stuff

However I then went and looked at the whole function and frankly it's a bit of a WTF. As best I could decipher, this whole crazy loop appears to be a baroque reinvention of:

	list_for_each_entry_safe(&params->params, ..., buf) {
		list_del(&buf->queue);
		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
	}

(assuming from context that the list should never contain more than RKISP1_ISP_PARAMS_REQ_BUFS_MAX entries in the first place)

Robin.

@@ -1508,6 +1502,7 @@ static void rkisp1_params_vb2_stop_streaming(struct vb2_queue *vq)
  			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
  		buf = NULL;
  	}
+	spin_unlock_irqrestore(&params->config_lock, flags);
  }
static int




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