[PATCH v2 2/2] media: v4l2-mem2mem: simplify poll logic

[Alexandre Courbot]

Factorize redundant checks into a single code block, remove unneeded
checks (a buffer in done_list is necessarily in the DONE or ERROR
state), and we end up with a much simpler version of this function.

Signed-off-by: Alexandre Courbot <gnu...@gmail.com>
---
 drivers/media/v4l2-core/v4l2-mem2mem.c | 26 +++++---------------------
 1 file changed, 5 insertions(+), 21 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c 
b/drivers/media/v4l2-core/v4l2-mem2mem.c
index fe90c3c0e4128..af8138c5d7ced 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;
 
@@ -862,32 +861,17 @@ static __poll_t v4l2_m2m_poll_for_data(struct file *file,
             list_empty(&dst_q->queued_list)))
                return EPOLLERR;
 
-       spin_lock_irqsave(&dst_q->done_lock, flags);
-       if (list_empty(&dst_q->done_list)) {
-               /*
-                * If the last buffer was dequeued from the capture queue,
-                * return immediately. DQBUF will return -EPIPE.
-                */
-               if (dst_q->last_buffer_dequeued)
-                       rc |= EPOLLIN | EPOLLRDNORM;
-       }
-       spin_unlock_irqrestore(&dst_q->done_lock, flags);
-
        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;
        spin_unlock_irqrestore(&src_q->done_lock, flags);
 
        spin_lock_irqsave(&dst_q->done_lock, flags);
-       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))
+       /*
+        * If the last buffer was dequeued from the capture queue, signal
+        * userspace. DQBUF(CAPTURE) will return -EPIPE.
+        */
+       if (!list_empty(&dst_q->done_list) || dst_q->last_buffer_dequeued)
                rc |= EPOLLIN | EPOLLRDNORM;
        spin_unlock_irqrestore(&dst_q->done_lock, flags);
 
-- 
2.28.0