gpu: nvgpu: gk20a: check the return value of gk20a_channel_busy

gk20a_channel_busy is called to host gpu so that gk20a can be accessed.
But it may return error like if gpu fails to be powered on. Always check
the return value of gk20a_channel_busy to avoid illegal access to gk20a.

Bug 1488409

Change-Id: Ie22da9e436ee5ea711003530419f546a73791b73
Signed-off-by: Kerwin Wan <kerwinw@nvidia.com>
Reviewed-on: http://git-master/r/395180
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c b/drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c
index da7d733e..bc5dc4c1 100644
--- a/drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c
@@ -555,7 +555,9 @@ static int dbg_set_powergate(struct dbg_session_gk20a *dbg_s,
 
                         gk20a_dbg(gpu_dbg_gpu_dbg | gpu_dbg_fn, "module busy");
                         gk20a_busy(g->dev);
-                        gk20a_channel_busy(dbg_s->pdev);
+                        err = gk20a_channel_busy(dbg_s->pdev);
+                        if (err)
+                                return -EPERM;
 
                         g->ops.clock_gating.slcg_gr_load_gating_prod(g,
                                         false);