of: overlay: detect cases where device tree may become corrupt

When an attempt to apply an overlay changeset fails, an effort
is made to revert any partial application of the changeset.
When an attempt to remove an overlay changeset fails, an effort
is made to re-apply any partial reversion of the changeset.

The existing code does not check for failure to recover a failed
overlay changeset application or overlay changeset revert.

Add the missing checks and flag the devicetree as corrupt if the
state of the devicetree can not be determined.

Improve and expand the returned errors to more fully reflect the
result of the effort to undo the partial effects of a failed attempt
to apply or remove an overlay changeset.

If the device tree might be corrupt, do not allow further attempts
to apply or remove an overlay changeset.

When creating an overlay changeset from an overlay device tree,
add some additional warnings if the state of the overlay device
tree is not as expected.

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c b/drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c
index 5f5b7ba35f1d..7a7be0515bfd 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c
@@ -204,7 +204,7 @@ static void __init tilcdc_convert_slave_node(void)
         /* For all memory needed for the overlay tree. This memory can
            be freed after the overlay has been applied. */
         struct kfree_table kft;
-        int ret;
+        int ovcs_id, ret;
 
         if (kfree_table_init(&kft))
                 return;
@@ -247,7 +247,8 @@ static void __init tilcdc_convert_slave_node(void)
 
         tilcdc_node_disable(slave);
 
-        ret = of_overlay_apply(overlay);
+        ovcs_id = 0;
+        ret = of_overlay_apply(overlay, &ovcs_id);
         if (ret)
                 pr_err("%s: Applying overlay changeset failed: %d\n",
                         __func__, ret);