gpu: nvgpu: cde: ignore spurious context releases

Gpu channels may get spurious updates from at least nonstalling
semaphore wait interrupts. Protect data structure sanity by ignoring
releases on already released (= not in use) cde contexts.

Bug 200062826

Change-Id: I5940a7557e902bcfcff1a7e8e4593472d9ac306c
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/666235
(cherry picked from commit 47dc2f41eb8054b099b6eb9a4a7d82c97295d415)
Reviewed-on: http://git-master/r/666657
GVS: Gerrit_Virtual_Submit
Reviewed-by: Arto Merilainen <amerilainen@nvidia.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/cde_gk20a.c b/drivers/gpu/nvgpu/gk20a/cde_gk20a.c
index f3185dd9..6f629e81 100644
--- a/drivers/gpu/nvgpu/gk20a/cde_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/cde_gk20a.c
@@ -759,12 +759,13 @@ __releases(&cde_app->mutex)
 
         mutex_lock(&cde_app->mutex);
 
-        if (!cde_ctx->in_use)
+        if (cde_ctx->in_use) {
+                cde_ctx->in_use = false;
+                list_move(&cde_ctx->list, &cde_app->free_contexts);
+                cde_app->ctx_usecount--;
+        } else {
                 gk20a_dbg_info("double release cde context %p", cde_ctx);
-
-        cde_ctx->in_use = false;
-        list_move(&cde_ctx->list, &cde_app->free_contexts);
-        cde_app->ctx_usecount--;
+        }
 
         mutex_unlock(&cde_app->mutex);
 }