ubi: Rewrite freePriority
freePriority is called by RedundancyPriority::priority() to ensure that
there are no duplicate priority values. Originally, freePriority would
call priority() whenever it updated a priority value, but this would call
freePriority again. This can cause the priorities stored on flash to not
match the D-Bus values. The priorities on flash are used to determine
which version to boot from so that leads to unexpected behavior.
Example is if A has priority 1 and B has priority 2, and the priority of
B is changed to 1, this triggers the new value of 1 to be stored on
flash, then A is bumped to 2, but then B that originally had 2 is bumped
to 3, so that at the end of the operation, B has priority 3 on flash but
the correct 1 in D-Bus.
The solution is to prevent freePriority from calling itself, by sorting
all versions by priority in ascending order, so that if a version is
bumped, then only the remaining versions need to be checked. Then
locally update the priority values on flash and on D-Bus for each
changed one.
Tested: Changed priorities multipled times and verified the mismatch is not
seen anymore.
Change-Id: I704ee98f356a1a77f431b83e4b9d787b2671aeb2
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/item_updater.hpp b/item_updater.hpp
index 3260003..01466bb 100644
--- a/item_updater.hpp
+++ b/item_updater.hpp
@@ -94,7 +94,9 @@
virtual ~ItemUpdater() = default;
/** @brief Sets the given priority free by incrementing
- * any existing priority with the same value by 1
+ * any existing priority with the same value by 1. It will then continue
+ * to resolve duplicate priorities caused by this increase, by increasing
+ * the priority by 1 until there are no more duplicate values.
*
* @param[in] value - The priority that needs to be set free.
* @param[in] versionId - The Id of the version for which we