From b18a8ff29d80b132018d33479e86ab8ecaee6b46 Mon Sep 17 00:00:00 2001
From: Hans Verkuil <hans.verkuil@cisco.com>
Date: Fri, 13 Dec 2013 13:13:38 -0300
Subject: [PATCH] [media] vb2: push the mmap semaphore down to __buf_prepare()

Rather than taking the mmap semaphore at a relatively high-level function,
push it down to the place where it is really needed.

It was placed in vb2_queue_or_prepare_buf() to prevent racing with other
vb2 calls. The only way I can see that a race can happen is when two
threads queue the same buffer. The solution for that it to introduce
a PREPARING state.

Moving it down offers opportunities to simplify the code.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
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