From d53e3d5fe0b97ebcec5340dc4f44faf2b1a5d52f Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Fri, 16 Oct 2015 14:20:36 -0400 Subject: [PATCH] Remove volatile qualifiers from proc.c and procarray.c Prior to commit 0709b7ee72e4bc71ad07b7120acd117265ab51d0, access to variables within a spinlock-protected critical section had to be done through a volatile pointer, but that should no longer be necessary. Michael Paquier --- src/backend/storage/ipc/procarray.c | 20 +++++++---------- src/backend/storage/lmgr/proc.c | 35 +++++++++-------------------- 2 files changed, 19 insertions(+), 36 deletions(-) diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index b13fe03993..0dc41170fe 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -3718,8 +3718,6 @@ static int KnownAssignedXidsGetAndSetXmin(TransactionId *xarray, TransactionId *xmin, TransactionId xmax) { - /* use volatile pointer to prevent code rearrangement */ - volatile ProcArrayStruct *pArray = procArray; int count = 0; int head, tail; @@ -3734,10 +3732,10 @@ KnownAssignedXidsGetAndSetXmin(TransactionId *xarray, TransactionId *xmin, * * Must take spinlock to ensure we see up-to-date array contents. */ - SpinLockAcquire(&pArray->known_assigned_xids_lck); - tail = pArray->tailKnownAssignedXids; - head = pArray->headKnownAssignedXids; - SpinLockRelease(&pArray->known_assigned_xids_lck); + SpinLockAcquire(&procArray->known_assigned_xids_lck); + tail = procArray->tailKnownAssignedXids; + head = procArray->headKnownAssignedXids; + SpinLockRelease(&procArray->known_assigned_xids_lck); for (i = tail; i < head; i++) { @@ -3777,8 +3775,6 @@ KnownAssignedXidsGetAndSetXmin(TransactionId *xarray, TransactionId *xmin, static TransactionId KnownAssignedXidsGetOldestXmin(void) { - /* use volatile pointer to prevent code rearrangement */ - volatile ProcArrayStruct *pArray = procArray; int head, tail; int i; @@ -3786,10 +3782,10 @@ KnownAssignedXidsGetOldestXmin(void) /* * Fetch head just once, since it may change while we loop. */ - SpinLockAcquire(&pArray->known_assigned_xids_lck); - tail = pArray->tailKnownAssignedXids; - head = pArray->headKnownAssignedXids; - SpinLockRelease(&pArray->known_assigned_xids_lck); + SpinLockAcquire(&procArray->known_assigned_xids_lck); + tail = procArray->tailKnownAssignedXids; + head = procArray->headKnownAssignedXids; + SpinLockRelease(&procArray->known_assigned_xids_lck); for (i = tail; i < head; i++) { diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index 2c2535b7b1..bb10c1bed0 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -283,15 +283,13 @@ InitProcGlobal(void) void InitProcess(void) { - /* use volatile pointer to prevent code rearrangement */ - volatile PROC_HDR *procglobal = ProcGlobal; PGPROC * volatile * procgloballist; /* * ProcGlobal should be set up already (if we are a backend, we inherit * this by fork() or EXEC_BACKEND mechanism from the postmaster). */ - if (procglobal == NULL) + if (ProcGlobal == NULL) elog(PANIC, "proc header uninitialized"); if (MyProc != NULL) @@ -299,11 +297,11 @@ InitProcess(void) /* Decide which list should supply our PGPROC. */ if (IsAnyAutoVacuumProcess()) - procgloballist = &procglobal->autovacFreeProcs; + procgloballist = &ProcGlobal->autovacFreeProcs; else if (IsBackgroundWorker) - procgloballist = &procglobal->bgworkerFreeProcs; + procgloballist = &ProcGlobal->bgworkerFreeProcs; else - procgloballist = &procglobal->freeProcs; + procgloballist = &ProcGlobal->freeProcs; /* * Try to get a proc struct from the appropriate free list. If this @@ -314,7 +312,7 @@ InitProcess(void) */ SpinLockAcquire(ProcStructLock); - set_spins_per_delay(procglobal->spins_per_delay); + set_spins_per_delay(ProcGlobal->spins_per_delay); MyProc = *procgloballist; @@ -578,13 +576,10 @@ InitAuxiliaryProcess(void) void PublishStartupProcessInformation(void) { - /* use volatile pointer to prevent code rearrangement */ - volatile PROC_HDR *procglobal = ProcGlobal; - SpinLockAcquire(ProcStructLock); - procglobal->startupProc = MyProc; - procglobal->startupProcPid = MyProcPid; + ProcGlobal->startupProc = MyProc; + ProcGlobal->startupProcPid = MyProcPid; SpinLockRelease(ProcStructLock); } @@ -627,12 +622,9 @@ HaveNFreeProcs(int n) { PGPROC *proc; - /* use volatile pointer to prevent code rearrangement */ - volatile PROC_HDR *procglobal = ProcGlobal; - SpinLockAcquire(ProcStructLock); - proc = procglobal->freeProcs; + proc = ProcGlobal->freeProcs; while (n > 0 && proc != NULL) { @@ -772,8 +764,6 @@ RemoveProcFromArray(int code, Datum arg) static void ProcKill(int code, Datum arg) { - /* use volatile pointer to prevent code rearrangement */ - volatile PROC_HDR *procglobal = ProcGlobal; PGPROC *proc; PGPROC * volatile * procgloballist; @@ -822,7 +812,7 @@ ProcKill(int code, Datum arg) *procgloballist = proc; /* Update shared estimate of spins_per_delay */ - procglobal->spins_per_delay = update_spins_per_delay(procglobal->spins_per_delay); + ProcGlobal->spins_per_delay = update_spins_per_delay(ProcGlobal->spins_per_delay); SpinLockRelease(ProcStructLock); @@ -1644,9 +1634,6 @@ ProcSendSignal(int pid) if (RecoveryInProgress()) { - /* use volatile pointer to prevent code rearrangement */ - volatile PROC_HDR *procglobal = ProcGlobal; - SpinLockAcquire(ProcStructLock); /* @@ -1657,8 +1644,8 @@ ProcSendSignal(int pid) * backend, so BackendPidGetProc() will not return any pid at all. So * we remember the information for this special case. */ - if (pid == procglobal->startupProcPid) - proc = procglobal->startupProc; + if (pid == ProcGlobal->startupProcPid) + proc = ProcGlobal->startupProc; SpinLockRelease(ProcStructLock); } -- 2.40.0