gpu: nvgpu: fix race between do_idle() and unrailgate()

While we are executing do_idle() API, it is possible that
unrailgate() gets invoked in midst of idling the GPU and
this can result in failure of do_idle()

To prevent simultaneous execution of these methods,
add a mutex railgate_lock and acquire it during
do_idle() and unrailgate() APIs

Also, keep this lock held if do_idle() is successful.
In success, lock will be released in do_unidle(),
otherwise release this lock before returning

Note that this lock should not be held in railgate() API
since we do not want it to be blocked during do_idle()

bug 1529160

Change-Id: I87114b5367eaa217376455a2699c0d21c451c889
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/434190
(cherry picked from commit 561dc8e0933ff2d72573292968b893a52f5f783a)
Reviewed-on: http://git-master/r/435131
Reviewed-by: Arto Merilainen <amerilainen@nvidia.com>
Reviewed-by: Sachin Nikam <snikam@nvidia.com>

0 files changed, 0 insertions, 0 deletions