gpu: nvgpu: fix race condition with poweroff

When gpu rail-gating is enabled, it is possible that
both rail gating code and system shudown can start
executing gk20a_pm_prepare_poweroff() in parallel.
To synchronize this execution, protect gk20a_pm_prepare_poweroff()
with a mutex lock.

Bug 200168805

Change-Id: I19536a43ed20c3e82b32c316922dc3e19e3f59bb
Signed-off-by: Seshendra Gadagottu <sgadagottu@nvidia.com>
Reviewed-on: http://git-master/r/999548
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a.h b/drivers/gpu/nvgpu/gk20a/gk20a.h
index b02d6111..0207588f 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/gk20a.h
@@ -521,6 +521,8 @@ struct gk20a {
 
         struct mutex ch_wdt_lock;
 
+        struct mutex poweroff_lock;
+
         /* Channel priorities */
         u32 timeslice_low_priority_us;
         u32 timeslice_medium_priority_us;