drm: fix uninitialized acquire_ctx fields (v2)

The acquire ctx will typically be declared on the stack, which means we
could have garbage values for any uninitialized field.  In this case, it
was triggering WARN_ON()s because 'contended' had garbage value.

Go ahead and use memset() to be more future-proof.

v2: now with extra brown paper bag

Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
index 7c2497dea1e9924d5a63f854af6ecbae19087dc2..0dc57d5ecd10d1e7e777c04817b0fd1a67df79e9 100644 (file)
--- a/drivers/gpu/drm/drm_modeset_lock.c
+++ b/drivers/gpu/drm/drm_modeset_lock.c
@@ -64,6 +64,7 @@
 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
                uint32_t flags)
 {
+       memset(ctx, 0, sizeof(*ctx));
        ww_acquire_init(&ctx->ww_ctx, &crtc_ww_class);
        INIT_LIST_HEAD(&ctx->locked);
 }