V4L/DVB (7488): videobuf: Simplify videobuf_waiton logic and possibly avoid missed wakeup

Possible missed wakeup- use kernel helpers for wait queues
  http://www.mail-archive.com/linux-usb-devel@lists.sourceforge.net/msg27983.html

Signed-off-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 15 insertions, 22 deletions

diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c
index e4a864e0d96b..1ba3aaa29dd0 100644
--- a/drivers/media/video/videobuf-core.c
+++ b/drivers/media/video/videobuf-core.c
@@ -64,32 +64,25 @@ void *videobuf_alloc(struct videobuf_queue *q)
         return vb;
 }
 
+#define WAITON_CONDITION (vb->state != VIDEOBUF_ACTIVE &&\
+                                vb->state != VIDEOBUF_QUEUED)
 int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr)
 {
-        int retval = 0;
-        DECLARE_WAITQUEUE(wait, current);
-
         MAGIC_CHECK(vb->magic, MAGIC_BUFFER);
-        add_wait_queue(&vb->done, &wait);
-        while (vb->state == VIDEOBUF_ACTIVE || vb->state == VIDEOBUF_QUEUED) {
-                if (non_blocking) {
-                        retval = -EAGAIN;
-                        break;
-                }
-                set_current_state(intr  ? TASK_INTERRUPTIBLE
-                                        : TASK_UNINTERRUPTIBLE);
-                if (vb->state == VIDEOBUF_ACTIVE ||
-                    vb->state == VIDEOBUF_QUEUED)
-                        schedule();
-                set_current_state(TASK_RUNNING);
-                if (intr && signal_pending(current)) {
-                        dprintk(1, "buffer waiton: -EINTR\n");
-                        retval = -EINTR;
-                        break;
-                }
+
+        if (non_blocking) {
+                if (WAITON_CONDITION)
+                        return 0;
+                else
+                        return -EAGAIN;
         }
-        remove_wait_queue(&vb->done, &wait);
-        return retval;
+
+        if (intr)
+                return wait_event_interruptible(vb->done, WAITON_CONDITION);
+        else
+                wait_event(vb->done, WAITON_CONDITION);
+
+        return 0;
 }
 
 int videobuf_iolock(struct videobuf_queue *q, struct videobuf_buffer *vb,