From 87a3023c60f4bab551441492652ef19371847fd3 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Mon, 30 May 2016 15:35:53 -0700
Subject: [PATCH] Move memory barrier in UnlockBufHdr to before releasing the
lock.
This bug appears to have been introduced late in the development of
48354581a4 ("Allow Pin/UnpinBuffer to operate in a lockfree
manner.").
Found while debugging a bug which turned out to be independent of the
commit mentioned above.
Backpatch: -
---
src/include/storage/buf_internals.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h
index c9cae956a54..511d7409e6e 100644
--- a/src/include/storage/buf_internals.h
+++ b/src/include/storage/buf_internals.h
@@ -242,8 +242,8 @@ extern PGDLLIMPORT LWLockMinimallyPadded *BufferIOLWLockArray;
extern uint32 LockBufHdr(BufferDesc *desc);
#define UnlockBufHdr(desc, s) \
do { \
- pg_atomic_write_u32(&(desc)->state, (s) & (~BM_LOCKED)); \
pg_write_barrier(); \
+ pg_atomic_write_u32(&(desc)->state, (s) & (~BM_LOCKED)); \
} while (0)
--
GitLab