Mark FastPathStrongRelationLocks volatile.

robertmhaas · robertmhaas · commit e980ec7c8071 · 2014-03-31T14:38:18.000-04:00
Otherwise, the compiler might decide to move modifications to data
within this structure outside the enclosing SpinLockAcquire /
SpinLockRelease pair, leading to shared memory corruption.

This may or may not explain a recent lmgr-related buildfarm failure
on prairiedog, but it needs to be fixed either way.
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
@@ -237,7 +237,7 @@ typedef struct
 	uint32		count[FAST_PATH_STRONG_LOCK_HASH_PARTITIONS];
 } FastPathStrongRelationLockData;
 
-FastPathStrongRelationLockData *FastPathStrongRelationLocks;
+volatile FastPathStrongRelationLockData *FastPathStrongRelationLocks;
 
 
 /*
