[PATCH 2/2] media: v4l2-mem2mem: simplify poll logic a bit

[Alexandre Courbot]

Factorize redundant checks into a single code block, remove the early
return, and declare variables in their innermost block. Hopefully this
makes this code a little bit easier to follow.

Signed-off-by: Alexandre Courbot <gnu...@gmail.com>
---
 drivers/media/v4l2-core/v4l2-mem2mem.c | 35 +++++++++++---------------
 1 file changed, 15 insertions(+), 20 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c 
b/drivers/media/v4l2-core/v4l2-mem2mem.c
index 0d0192119af20..aeac9707123d0 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -841,7 +841,6 @@ static __poll_t v4l2_m2m_poll_for_data(struct file *file,
                                       struct poll_table_struct *wait)
 {
        struct vb2_queue *src_q, *dst_q;
-       struct vb2_buffer *src_vb = NULL, *dst_vb = NULL;
        __poll_t rc = 0;
        unsigned long flags;
 
@@ -863,33 +862,29 @@ static __poll_t v4l2_m2m_poll_for_data(struct file *file,
                return EPOLLERR;
 
        spin_lock_irqsave(&src_q->done_lock, flags);
-       if (!list_empty(&src_q->done_list))
-               src_vb = list_first_entry(&src_q->done_list, struct vb2_buffer,
-                                               done_entry);
-       if (src_vb && (src_vb->state == VB2_BUF_STATE_DONE
-                       || src_vb->state == VB2_BUF_STATE_ERROR))
-               rc |= EPOLLOUT | EPOLLWRNORM;
+       if (!list_empty(&src_q->done_list)) {
+               struct vb2_buffer *src_vb = list_first_entry(
+                       &src_q->done_list, struct vb2_buffer, done_entry);
+               if (src_vb->state == VB2_BUF_STATE_DONE ||
+                   src_vb->state == VB2_BUF_STATE_ERROR)
+                       rc |= EPOLLOUT | EPOLLWRNORM;
+       }
        spin_unlock_irqrestore(&src_q->done_lock, flags);
 
        spin_lock_irqsave(&dst_q->done_lock, flags);
-       if (list_empty(&dst_q->done_list)) {
+       if (!list_empty(&dst_q->done_list)) {
+               struct vb2_buffer *dst_vb = list_first_entry(
+                       &dst_q->done_list, struct vb2_buffer, done_entry);
+               if (dst_vb->state == VB2_BUF_STATE_DONE ||
+                   dst_vb->state == VB2_BUF_STATE_ERROR)
+                       rc |= EPOLLIN | EPOLLRDNORM;
+       } else if (dst_q->last_buffer_dequeued) {
                /*
                 * If the last buffer was dequeued from the capture queue,
                 * return immediately. DQBUF will return -EPIPE.
                 */
-               if (dst_q->last_buffer_dequeued) {
-                       spin_unlock_irqrestore(&dst_q->done_lock, flags);
-                       rc |= EPOLLIN | EPOLLRDNORM;
-                       return rc;
-               }
-       }
-
-       if (!list_empty(&dst_q->done_list))
-               dst_vb = list_first_entry(&dst_q->done_list, struct vb2_buffer,
-                                               done_entry);
-       if (dst_vb && (dst_vb->state == VB2_BUF_STATE_DONE
-                       || dst_vb->state == VB2_BUF_STATE_ERROR))
                rc |= EPOLLIN | EPOLLRDNORM;
+       }
        spin_unlock_irqrestore(&dst_q->done_lock, flags);
 
        return rc;
-- 
2.28.0