[PATCH] videobuf_qbuf: fix? possible videobuf_queue->stream corruption and lockup

[Oleg Nesterov <oleg@tv-sign.ru>]

I am pretty sure the bug is real, but the patch may be wrong, please review.

We are doing ->buf_prepare(buf) before adding buf to q->stream list. This
means that videobuf_qbuf() should not try to re-add a STATE_PREPARED buffer.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- 6.19/drivers/media/video/video-buf.c~v4l_lockup	2006-11-17 19:42:25.000000000 +0300
+++ 6.19/drivers/media/video/video-buf.c	2007-01-23 19:44:19.000000000 +0300
@@ -700,6 +700,7 @@ videobuf_qbuf(struct videobuf_queue *q,
 		goto done;
 	}
 	if (buf->state == STATE_QUEUED ||
+	    buf->state == STATE_PREPARED ||
 	    buf->state == STATE_ACTIVE) {
 		dprintk(1,"qbuf: buffer is already queued or active.\n");
 		goto done;

-
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