Mark FastPathStrongRelationLocks volatile.

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
index 3e761027946aa6d9ee8a0bf9d27ad0e33e2f682c..0f218280090767e916c35742d66af1c0f992fd0a 100644 (file)
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -238,7 +238,7 @@ typedef struct
    uint32      count[FAST_PATH_STRONG_LOCK_HASH_PARTITIONS];
 } FastPathStrongRelationLockData;
 
-FastPathStrongRelationLockData *FastPathStrongRelationLocks;
+volatile FastPathStrongRelationLockData *FastPathStrongRelationLocks;
 
 
 /*