[PATCH] drm/msm: Fix objtool warning in submit_lock_objects()

[Sasha Levin]

Restructure submit_lock_objects() to use a single loop with break
statements to fix objtool warning:

  drivers/gpu/drm/msm/msm.o: warning: objtool: submit_lock_objects+0x451:
  sibling call from callable instruction with modified stack frame

The drm_exec_until_all_locked() macro uses computed gotos internally
for its retry loop. Having return statements inside this macro, or
immediately after it in certain code paths, confuses objtool's static
analysis of stack frames, causing it to incorrectly flag tail call
optimizations.

Fixes: 92395af63a99 ("drm/msm: Add VM_BIND submitqueue")
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/gpu/drm/msm/msm_gem_submit.c | 43 ++++++++++++----------------
 1 file changed, 19 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c 
b/drivers/gpu/drm/msm/msm_gem_submit.c
index 5f8e939a5906..253347b6e328 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -276,46 +276,41 @@ static int submit_lock_objects(struct msm_gem_submit 
*submit)
 {
        unsigned flags = DRM_EXEC_INTERRUPTIBLE_WAIT;
        struct drm_exec *exec = &submit->exec;
-       int ret;
+       int ret = 0;
 
-       if (msm_context_is_vmbind(submit->queue->ctx)) {
+       if (msm_context_is_vmbind(submit->queue->ctx))
                flags |= DRM_EXEC_IGNORE_DUPLICATES;
 
-               drm_exec_init(&submit->exec, flags, submit->nr_bos);
+       drm_exec_init(&submit->exec, flags, submit->nr_bos);
 
-               drm_exec_until_all_locked (&submit->exec) {
+       drm_exec_until_all_locked (&submit->exec) {
+               if (msm_context_is_vmbind(submit->queue->ctx)) {
                        ret = drm_gpuvm_prepare_vm(submit->vm, exec, 1);
                        drm_exec_retry_on_contention(exec);
                        if (ret)
-                               return ret;
+                               break;
 
                        ret = drm_gpuvm_prepare_objects(submit->vm, exec, 1);
                        drm_exec_retry_on_contention(exec);
                        if (ret)
-                               return ret;
-               }
-
-               return 0;
-       }
-
-       drm_exec_init(&submit->exec, flags, submit->nr_bos);
-
-       drm_exec_until_all_locked (&submit->exec) {
-               ret = drm_exec_lock_obj(&submit->exec,
-                                       drm_gpuvm_resv_obj(submit->vm));
-               drm_exec_retry_on_contention(&submit->exec);
-               if (ret)
-                       return ret;
-               for (unsigned i = 0; i < submit->nr_bos; i++) {
-                       struct drm_gem_object *obj = submit->bos[i].obj;
-                       ret = drm_exec_prepare_obj(&submit->exec, obj, 1);
+                               break;
+               } else {
+                       ret = drm_exec_lock_obj(&submit->exec,
+                                               drm_gpuvm_resv_obj(submit->vm));
                        drm_exec_retry_on_contention(&submit->exec);
                        if (ret)
-                               return ret;
+                               break;
+                       for (unsigned i = 0; i < submit->nr_bos; i++) {
+                               struct drm_gem_object *obj = submit->bos[i].obj;
+                               ret = drm_exec_prepare_obj(&submit->exec, obj, 
1);
+                               drm_exec_retry_on_contention(&submit->exec);
+                               if (ret)
+                                       break;
+                       }
                }
        }
 
-       return 0;
+       return ret;
 }
 
 static int submit_fence_sync(struct msm_gem_submit *submit)
-- 
2.39.5