of/unittest: fix infinite loop in of_unittest_destroy_tracked_overlays()

of_overlay_destroy() can return `-ENODEV' error code once it
failed to find the requested overlay in `ov_idr'. However,
of_unittest_destroy_tracked_overlays() does not handle this
error code correctly and continues to call of_overlay_destroy()
on the 'missing' overlay over and over again. This results in
a printk flood

[..]
[   33.497583] of_overlay_destroy: Could not find overlay #6
[   33.497583] of_overlay_destroy: Could not find overlay #6
[   33.497584] ### dt-test ### of_unittest_destroy_tracked_overlays: overlay destroy failed for #6
[   33.497584] ### dt-test ### of_unittest_destroy_tracked_overlays: overlay destroy failed for #6
[   33.497586] of_overlay_destroy: Could not find overlay #6
[   33.497586] of_overlay_destroy: Could not find overlay #6
[   33.497587] ### dt-test ### of_unittest_destroy_tracked_overlays: overlay destroy failed for #6
[   33.497587] ### dt-test ### of_unittest_destroy_tracked_overlays: overlay destroy failed for #6
[..]

which is not really good due to printk design, and can lead to soft
lockups, hard lockups, etc. (depending on the context console_unlock()
is being called from). The problem has bee observed in real life
and reported by Ying Huang.

This patch does not address the root cause of missing overlay in
`ov_idr', it fixes the endless loop only.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: kernel test robot <ying.huang@linux.intel.com>
Link: lkml.kernel.org/r/87fuwk1c0o.fsf@yhuang-dev.intel.com
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 979b6e4..e986e6e 100644 (file)
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1165,6 +1165,11 @@ static void of_unittest_destroy_tracked_overlays(void)
                                continue;
 
                        ret = of_overlay_destroy(id + overlay_first_id);
+                       if (ret == -ENODEV) {
+                               pr_warn("%s: no overlay to destroy for #%d\n",
+                                       __func__, id + overlay_first_id);
+                               continue;
+                       }
                        if (ret != 0) {
                                defers++;
                                pr_warn("%s: overlay destroy failed for #%d\n",