database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-26 23:43:30 +03:00
Code Activity

Do all accesses to shared buffer headers through volatile-qualified

Browse Source 
pointers, to ensure that compilers won't rearrange accesses to occur
while we're not holding the buffer header spinlock.  It's probably
not necessary to mark volatile in every single place in bufmgr.c,
but better safe than sorry.  Per trouble report from Kevin Grittner.
This commit is contained in:
Tom Lane
2005-10-12 16:45:14 +00:00
parent 6b97e437ca
commit 07eeb9d109
4 changed files with 64 additions and 71 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
src/include/storage/buf_internals.h
View File

@@ -8,7 +8,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.79 2005/08/20 23:26:33 tgl Exp $
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.80 2005/10/12 16:45:14 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -145,6 +145,11 @@ typedef struct sbufdesc
* NoHoldoff cases may be used when we know that we hold some LWLock
* and therefore interrupts are already held off. Do not apply these
* to local buffers!
*
* Note: as a general coding rule, if you are using these then you probably
* want to be using a volatile-qualified pointer to the buffer header, to
* ensure that the compiler doesn't rearrange accesses to the header to
* occur before or after the spinlock is acquired/released.
*/
#define LockBufHdr(bufHdr) \
SpinLockAcquire(&(bufHdr)->buf_hdr_lock)
@@ -179,8 +184,8 @@ extern long int LocalBufferFlushCount;
*/
/* freelist.c */
extern BufferDesc *StrategyGetBuffer(void);
extern void StrategyFreeBuffer(BufferDesc *buf, bool at_head);
extern volatile BufferDesc *StrategyGetBuffer(void);
extern void StrategyFreeBuffer(volatile BufferDesc *buf, bool at_head);
extern int StrategySyncStart(void);
extern Size StrategyShmemSize(void);
extern void StrategyInitialize(bool init);