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Remove unnecessary volatile qualifiers.

Browse source 
This commit cleans up volatile qualifiers that fit the below
criteria:

* Accesses to shared memory protected by a spinlock or LWLock.
Before commit 0709b7ee72, callers had to use volatile when
accessing spinlock-protected shared memory.  Since spinlock
acquire/release became compiler barriers, and because LWLocks
provide the same guarantee, that is no longer necessary.  These
either predate that change or were cargo-culted from code that did.

* Pointers used only to find the address of a member.  The volatile
qualifier only affects accesses made by dereferencing the pointer,
so it is unnecessary there.

* Accesses to struct members that are marked volatile in the struct
definition.  There's no need to mark these pointers volatile,
either.

* Leftovers from removed PG_TRY blocks.  These were marked volatile
to protect a value that is modified inside a PG_TRY block, but the
PG_TRY has since been removed.

Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://postgr.es/m/akQ5eJR1tCCXme8e%40nathan
This commit is contained in:
Nathan Bossart 2026-07-07 10:57:48 -05:00
parent 343594a26d
commit b34fd845e0
10 changed files with 37 additions and 45 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
src/backend/access/transam/clog.c
View file

@ -450,7 +450,6 @@ static bool
TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
XLogRecPtr lsn, int64 pageno)
{
volatile PROC_HDR *procglobal = ProcGlobal;
PGPROC *proc = MyProc;
uint32 nextidx;
uint32 wakeidx;
@ -493,7 +492,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
* different from ours. If another group starts to update a page in the
* same bank as ours, they wait until we release the lock.
*/
nextidx = pg_atomic_read_u32(&procglobal->clogGroupFirst);
nextidx = pg_atomic_read_u32(&ProcGlobal->clogGroupFirst);
while (true)
{
@ -524,7 +523,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
pg_atomic_write_u32(&proc->clogGroupNext, nextidx);
if (pg_atomic_compare_exchange_u32(&procglobal->clogGroupFirst,
if (pg_atomic_compare_exchange_u32(&ProcGlobal->clogGroupFirst,
&nextidx,
(uint32) MyProcNumber))
break;
@ -576,7 +575,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
* At this point, any processes trying to do this would create a separate
* group.
*/
nextidx = pg_atomic_exchange_u32(&procglobal->clogGroupFirst,
nextidx = pg_atomic_exchange_u32(&ProcGlobal->clogGroupFirst,
INVALID_PROC_NUMBER);
/* Remember head of list so we can perform wakeups after dropping lock. */

2
src/backend/catalog/index.c
View file

@ -3637,7 +3637,7 @@ reindex_index(const ReindexStmt *stmt, Oid indexId,
int save_sec_context;
int save_nestlevel;
IndexInfo *indexInfo;
volatile bool skipped_constraint = false;
bool skipped_constraint = false;
PGRUsage ru0;
bool progress = ((params->options & REINDEXOPT_REPORT_PROGRESS) != 0);
bool set_tablespace = false;

4
src/backend/commands/async.c
View file

@ -605,7 +605,7 @@ static void CleanupListenersOnExit(void);
static bool IsListeningOn(const char *channel);
static void asyncQueueUnregister(void);
static bool asyncQueueIsFull(void);
static bool asyncQueueAdvance(volatile QueuePosition *position, int entryLength);
static bool asyncQueueAdvance(QueuePosition *position, int entryLength);
static void asyncQueueNotificationToEntry(Notification *n, AsyncQueueEntry *qe);
static ListCell *asyncQueueAddEntries(ListCell *nextNotify);
static double asyncQueueUsage(void);
@ -1968,7 +1968,7 @@ asyncQueueIsFull(void)
* returns true, else false.
*/
static bool
asyncQueueAdvance(volatile QueuePosition *position, int entryLength)
asyncQueueAdvance(QueuePosition *position, int entryLength)
{
int64 pageno = QUEUE_POS_PAGE(*position);
int offset = QUEUE_POS_OFFSET(*position);

19
src/backend/replication/syncrep.c
View file

@ -483,7 +483,6 @@ SyncRepInitConfig(void)
void
SyncRepReleaseWaiters(void)
{
volatile WalSndCtlData *walsndctl = WalSndCtl;
XLogRecPtr writePtr;
XLogRecPtr flushPtr;
XLogRecPtr applyPtr;
@ -558,19 +557,19 @@ SyncRepReleaseWaiters(void)
* Set the lsn first so that when we wake backends they will release up to
* this location.
*/
if (walsndctl->lsn[SYNC_REP_WAIT_WRITE] < writePtr)
if (WalSndCtl->lsn[SYNC_REP_WAIT_WRITE] < writePtr)
{
walsndctl->lsn[SYNC_REP_WAIT_WRITE] = writePtr;
WalSndCtl->lsn[SYNC_REP_WAIT_WRITE] = writePtr;
numwrite = SyncRepWakeQueue(false, SYNC_REP_WAIT_WRITE);
}
if (walsndctl->lsn[SYNC_REP_WAIT_FLUSH] < flushPtr)
if (WalSndCtl->lsn[SYNC_REP_WAIT_FLUSH] < flushPtr)
{
walsndctl->lsn[SYNC_REP_WAIT_FLUSH] = flushPtr;
WalSndCtl->lsn[SYNC_REP_WAIT_FLUSH] = flushPtr;
numflush = SyncRepWakeQueue(false, SYNC_REP_WAIT_FLUSH);
}
if (walsndctl->lsn[SYNC_REP_WAIT_APPLY] < applyPtr)
if (WalSndCtl->lsn[SYNC_REP_WAIT_APPLY] < applyPtr)
{
walsndctl->lsn[SYNC_REP_WAIT_APPLY] = applyPtr;
WalSndCtl->lsn[SYNC_REP_WAIT_APPLY] = applyPtr;
numapply = SyncRepWakeQueue(false, SYNC_REP_WAIT_APPLY);
}
@ -777,8 +776,7 @@ SyncRepGetCandidateStandbys(SyncRepStandbyData **standbys)
n = 0;
for (i = 0; i < max_wal_senders; i++)
{
volatile WalSnd *walsnd; /* Use volatile pointer to prevent code
* rearrangement */
WalSnd *walsnd;
SyncRepStandbyData *stby;
WalSndState state; /* not included in SyncRepStandbyData */
@ -915,7 +913,6 @@ SyncRepGetStandbyPriority(void)
static int
SyncRepWakeQueue(bool all, int mode)
{
volatile WalSndCtlData *walsndctl = WalSndCtl;
int numprocs = 0;
dlist_mutable_iter iter;
@ -930,7 +927,7 @@ SyncRepWakeQueue(bool all, int mode)
/*
* Assume the queue is ordered by LSN
*/
if (!all && walsndctl->lsn[mode] < proc->waitLSN)
if (!all && WalSndCtl->lsn[mode] < proc->waitLSN)
return numprocs;
/*

8
src/backend/storage/ipc/procsignal.c
View file

@ -295,7 +295,7 @@ CleanupProcSignalState(int status, Datum arg)
int
SendProcSignal(pid_t pid, ProcSignalReason reason, ProcNumber procNumber)
{
volatile ProcSignalSlot *slot;
ProcSignalSlot *slot;
if (procNumber != INVALID_PROC_NUMBER)
{
@ -380,7 +380,7 @@ EmitProcSignalBarrier(ProcSignalBarrierType type)
*/
for (int i = 0; i < NumProcSignalSlots; i++)
{
volatile ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
pg_atomic_fetch_or_u32(&slot->pss_barrierCheckMask, flagbit);
}
@ -406,7 +406,7 @@ EmitProcSignalBarrier(ProcSignalBarrierType type)
*/
for (int i = NumProcSignalSlots - 1; i >= 0; i--)
{
volatile ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
pid_t pid = pg_atomic_read_u32(&slot->pss_pid);
if (pid != 0)
@ -670,7 +670,7 @@ ResetProcSignalBarrierBits(uint32 flags)
static bool
CheckProcSignal(ProcSignalReason reason)
{
volatile ProcSignalSlot *slot = MyProcSignalSlot;
ProcSignalSlot *slot = MyProcSignalSlot;
if (slot != NULL)
{

31
src/backend/storage/ipc/shm_toc.c
View file

@ -87,7 +87,6 @@ shm_toc_attach(uint64 magic, void *address)
void *
shm_toc_allocate(shm_toc *toc, Size nbytes)
{
volatile shm_toc *vtoc = toc;
Size total_bytes;
Size allocated_bytes;
Size nentry;
@ -103,9 +102,9 @@ shm_toc_allocate(shm_toc *toc, Size nbytes)
SpinLockAcquire(&toc->toc_mutex);
total_bytes = vtoc->toc_total_bytes;
allocated_bytes = vtoc->toc_allocated_bytes;
nentry = vtoc->toc_nentry;
total_bytes = toc->toc_total_bytes;
allocated_bytes = toc->toc_allocated_bytes;
nentry = toc->toc_nentry;
toc_bytes = offsetof(shm_toc, toc_entry) + nentry * sizeof(shm_toc_entry)
+ allocated_bytes;
@ -117,7 +116,7 @@ shm_toc_allocate(shm_toc *toc, Size nbytes)
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of shared memory")));
}
vtoc->toc_allocated_bytes += nbytes;
toc->toc_allocated_bytes += nbytes;
SpinLockRelease(&toc->toc_mutex);
@ -130,16 +129,15 @@ shm_toc_allocate(shm_toc *toc, Size nbytes)
Size
shm_toc_freespace(shm_toc *toc)
{
volatile shm_toc *vtoc = toc;
Size total_bytes;
Size allocated_bytes;
Size nentry;
Size toc_bytes;
SpinLockAcquire(&toc->toc_mutex);
total_bytes = vtoc->toc_total_bytes;
allocated_bytes = vtoc->toc_allocated_bytes;
nentry = vtoc->toc_nentry;
total_bytes = toc->toc_total_bytes;
allocated_bytes = toc->toc_allocated_bytes;
nentry = toc->toc_nentry;
SpinLockRelease(&toc->toc_mutex);
toc_bytes = offsetof(shm_toc, toc_entry) + nentry * sizeof(shm_toc_entry);
@ -170,7 +168,6 @@ shm_toc_freespace(shm_toc *toc)
void
shm_toc_insert(shm_toc *toc, uint64 key, void *address)
{
volatile shm_toc *vtoc = toc;
Size total_bytes;
Size allocated_bytes;
Size nentry;
@ -183,14 +180,14 @@ shm_toc_insert(shm_toc *toc, uint64 key, void *address)
SpinLockAcquire(&toc->toc_mutex);
total_bytes = vtoc->toc_total_bytes;
allocated_bytes = vtoc->toc_allocated_bytes;
nentry = vtoc->toc_nentry;
total_bytes = toc->toc_total_bytes;
allocated_bytes = toc->toc_allocated_bytes;
nentry = toc->toc_nentry;
#ifdef USE_ASSERT_CHECKING
/* Verify no duplicate keys */
for (Size i = 0; i < nentry; i++)
Assert(vtoc->toc_entry[i].key != key);
Assert(toc->toc_entry[i].key != key);
#endif
toc_bytes = offsetof(shm_toc, toc_entry) + nentry * sizeof(shm_toc_entry)
@ -208,8 +205,8 @@ shm_toc_insert(shm_toc *toc, uint64 key, void *address)
}
Assert(offset < total_bytes);
vtoc->toc_entry[nentry].key = key;
vtoc->toc_entry[nentry].offset = offset;
toc->toc_entry[nentry].key = key;
toc->toc_entry[nentry].offset = offset;
/*
* By placing a write barrier after filling in the entry and before
@ -218,7 +215,7 @@ shm_toc_insert(shm_toc *toc, uint64 key, void *address)
*/
pg_write_barrier();
vtoc->toc_nentry++;
toc->toc_nentry++;
SpinLockRelease(&toc->toc_mutex);
}

2
src/backend/storage/lmgr/lock.c
View file

@ -312,7 +312,7 @@ typedef struct
uint32 count[FAST_PATH_STRONG_LOCK_HASH_PARTITIONS];
} FastPathStrongRelationLockData;
static volatile FastPathStrongRelationLockData *FastPathStrongRelationLocks;
static FastPathStrongRelationLockData *FastPathStrongRelationLocks;
static void LockManagerShmemRequest(void *arg);
static void LockManagerShmemInit(void *arg);

3
src/backend/storage/lmgr/proc.c
View file

@ -660,8 +660,7 @@ InitAuxiliaryProcess(void)
}
/* Mark auxiliary proc as in use by me */
/* use volatile pointer to prevent code rearrangement */
((volatile PGPROC *) auxproc)->pid = MyProcPid;
auxproc->pid = MyProcPid;
SpinLockRelease(&ProcGlobal->freeProcsLock);

4
src/test/modules/test_shm_mq/setup.c
View file

@ -38,7 +38,7 @@ static worker_state *setup_background_workers(int nworkers,
dsm_segment *seg);
static void cleanup_background_workers(dsm_segment *seg, Datum arg);
static void wait_for_workers_to_become_ready(worker_state *wstate,
volatile test_shm_mq_header *hdr);
test_shm_mq_header *hdr);
static bool check_worker_status(worker_state *wstate);
/* value cached, fetched from shared memory */
@ -258,7 +258,7 @@ cleanup_background_workers(dsm_segment *seg, Datum arg)
static void
wait_for_workers_to_become_ready(worker_state *wstate,
volatile test_shm_mq_header *hdr)
test_shm_mq_header *hdr)
{
bool result = false;

2
src/test/modules/test_shm_mq/worker.c
View file

@ -52,7 +52,7 @@ test_shm_mq_main(Datum main_arg)
shm_toc *toc;
shm_mq_handle *inqh;
shm_mq_handle *outqh;
volatile test_shm_mq_header *hdr;
test_shm_mq_header *hdr;
int myworkernumber;
PGPROC *registrant;