[PATCH 2/2] of: some unittest overlays not untracked

[frowand.list@xxxxxxxxx]

From: Frank Rowand <frank.rowand@xxxxxxxx>

kernel test robot reported "WARNING: held lock freed!" triggered by
unittest_gpio_remove(), which should not have been called because
the related gpio overlay was not tracked.  Another overlay that
was tracked had previously used the same id as the gpio overlay
but had not been untracked when the overlay was removed.  Thus the
clean up function of_unittest_destroy_tracked_overlays() incorrectly
attempted to remove the reused overlay id.

Patch contents:

  - Create tracking related helper functions
  - Change BUG() to WARN_ON() for overlay id related issues
  - Add some additional error checking for valid overlay id values
  - Add the missing overlay untrack
  - update comment on expectation that overlay ids are assigned in
    sequence

Fixes: 492a22aceb75 ("of: unittest: overlay: Keep track of created overlays")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxx>
---
 drivers/of/unittest.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 25911ad1ce99..27f538f859a6 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1689,19 +1689,27 @@ static const char *overlay_name_from_nr(int nr)
 
 static const char *bus_path = "/testcase-data/overlay-node/test-bus";
 
-/* it is guaranteed that overlay ids are assigned in sequence */
+/* FIXME: it is NOT guaranteed that overlay ids are assigned in sequence */
+
 #define MAX_UNITTEST_OVERLAYS	256
 static unsigned long overlay_id_bits[BITS_TO_LONGS(MAX_UNITTEST_OVERLAYS)];
 static int overlay_first_id = -1;
 
+static long of_unittest_overlay_tracked(int id)
+{
+	if (WARN_ON(id >= MAX_UNITTEST_OVERLAYS))
+		return 0;
+	return overlay_id_bits[BIT_WORD(id)] & BIT_MASK(id);
+}
+
 static void of_unittest_track_overlay(int id)
 {
 	if (overlay_first_id < 0)
 		overlay_first_id = id;
 	id -= overlay_first_id;
 
-	/* we shouldn't need that many */
-	BUG_ON(id >= MAX_UNITTEST_OVERLAYS);
+	if (WARN_ON(id >= MAX_UNITTEST_OVERLAYS))
+		return;
 	overlay_id_bits[BIT_WORD(id)] |= BIT_MASK(id);
 }
 
@@ -1710,7 +1718,8 @@ static void of_unittest_untrack_overlay(int id)
 	if (overlay_first_id < 0)
 		return;
 	id -= overlay_first_id;
-	BUG_ON(id >= MAX_UNITTEST_OVERLAYS);
+	if (WARN_ON(id >= MAX_UNITTEST_OVERLAYS))
+		return;
 	overlay_id_bits[BIT_WORD(id)] &= ~BIT_MASK(id);
 }
 
@@ -1726,7 +1735,7 @@ static void of_unittest_destroy_tracked_overlays(void)
 		defers = 0;
 		/* remove in reverse order */
 		for (id = MAX_UNITTEST_OVERLAYS - 1; id >= 0; id--) {
-			if (!(overlay_id_bits[BIT_WORD(id)] & BIT_MASK(id)))
+			if (!of_unittest_overlay_tracked(id))
 				continue;
 
 			ovcs_id = id + overlay_first_id;
@@ -1743,7 +1752,7 @@ static void of_unittest_destroy_tracked_overlays(void)
 				continue;
 			}
 
-			overlay_id_bits[BIT_WORD(id)] &= ~BIT_MASK(id);
+			of_unittest_untrack_overlay(id);
 		}
 	} while (defers > 0);
 }
@@ -1804,7 +1813,7 @@ static int __init of_unittest_apply_revert_overlay_check(int overlay_nr,
 		int unittest_nr, int before, int after,
 		enum overlay_type ovtype)
 {
-	int ret, ovcs_id;
+	int ret, ovcs_id, save_id;
 
 	/* unittest device must be in before state */
 	if (of_unittest_device_exists(unittest_nr, ovtype) != before) {
@@ -1832,6 +1841,7 @@ static int __init of_unittest_apply_revert_overlay_check(int overlay_nr,
 		return -EINVAL;
 	}
 
+	save_id = ovcs_id;
 	ret = of_overlay_remove(&ovcs_id);
 	if (ret != 0) {
 		unittest(0, "%s failed to be destroyed @\"%s\"\n",
@@ -1839,6 +1849,7 @@ static int __init of_unittest_apply_revert_overlay_check(int overlay_nr,
 				unittest_path(unittest_nr, ovtype));
 		return ret;
 	}
+	of_unittest_untrack_overlay(save_id);
 
 	/* unittest device must be again in before state */
 	if (of_unittest_device_exists(unittest_nr, PDEV_OVERLAY) != before) {
@@ -2528,6 +2539,11 @@ static void __init of_unittest_overlay_gpio(void)
 	 * Similar to installing a driver as a module, the
 	 * driver is registered after applying the overlays.
 	 *
+	 * The overlays are applied by overlay_data_apply()
+	 * instead of of_unittest_apply_overlay() so that they
+	 * will not be tracked.  Thus they will not be removed
+	 * by of_unittest_destroy_tracked_overlays().
+	 *
 	 * - apply overlay_gpio_01
 	 * - apply overlay_gpio_02a
 	 * - apply overlay_gpio_02b
-- 
Frank Rowand <frank.rowand@xxxxxxxx>