Fix crash with RemoveFromWaitQueue() when detecting a deadlock.
Commit 5764f611e used dclist_delete_from() to remove the proc from the
wait queue. However, since it doesn't clear dist_node's next/prev to
NULL, it could call RemoveFromWaitQueue() twice: when the process
detects a deadlock and then when cleaning up locks on aborting the
transaction. The waiting lock information is cleared in the first
call, so it led to a crash in the second call.
Backpatch to v16, where the change was introduced.
Bug: #18031
Reported-by: Justin Pryzby, Alexander Lakhin
Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/ZKy4AdrLEfbqrxGJ%40telsasoft.com
Discussion: https://postgr.es/m/18031-ebe2d08cb405f6cc@postgresql.org
Backpatch-through: 16
Branch
------
REL_16_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/b4f14d2e433bf9f2499f07bcaca07b9ff13d641b
Modified Files
--------------
src/backend/storage/lmgr/lock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
