V4L/DVB (6997): Replace a very dirty hack on videobuf for a clean wait_event

In order to videobuf_iolock to work, mmap_mapper should be called first.
Otherwise, an OOPS is generated.

On some cases, .mmap file handler used to took some time to be called. On those
situations, mmap_mmapper() were called after iolock.

This patch properly waits for mmap_mapper to be called, otherwise generating an
error.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

2 files changed, 13 insertions, 4 deletions

diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c
index 43fe3f78c8df..c3adbd686ffe 100644
--- a/drivers/media/video/videobuf-core.c
+++ b/drivers/media/video/videobuf-core.c
@@ -98,13 +98,15 @@ int videobuf_iolock(struct videobuf_queue *q, struct videobuf_buffer *vb,
         MAGIC_CHECK(vb->magic, MAGIC_BUFFER);
         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 
-        /* FIXME: This is required to avoid OOPS on some cases,
+        /* This is required to avoid OOPS on some cases,
            since mmap_mapper() method should be called before _iolock.
            On some cases, the mmap_mapper() is called only after scheduling.
-
-           However, this way is just too dirty! Better to wait for some event.
          */
-        schedule_timeout(HZ);
+        wait_event_timeout(vb->done, q->is_mmapped, msecs_to_jiffies(100));
+        if (!q->is_mmapped) {
+                printk(KERN_ERR "Error: mmap_mapper() never called!\n");
+                return -EINVAL;
+        }
 
         return CALL(q, iolock, q, vb, fbuf);
 }
@@ -300,7 +302,11 @@ static int __videobuf_mmap_free(struct videobuf_queue *q)
 
         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 
+
         rc  = CALL(q, mmap_free, q);
+
+        q->is_mmapped = 0;
+
         if (rc < 0)
                 return rc;
 
@@ -1022,6 +1028,7 @@ int videobuf_mmap_mapper(struct videobuf_queue *q,
 
         mutex_lock(&q->lock);
         retval = CALL(q, mmap_mapper, q, vma);
+        q->is_mmapped = 1;
         mutex_unlock(&q->lock);
 
         return retval;
diff --git a/include/media/videobuf-core.h b/include/media/videobuf-core.h
index 7aa7a7b64c1b..97f14d469595 100644
--- a/include/media/videobuf-core.h
+++ b/include/media/videobuf-core.h
@@ -164,6 +164,8 @@ struct videobuf_queue {
 
         unsigned int               streaming:1;
         unsigned int               reading:1;
+        unsigned int               is_mmapped:1;
+
         /* capture via mmap() + ioctl(QBUF/DQBUF) */
         struct list_head           stream;