diff options
Diffstat (limited to 'src/backend/storage/ipc/spin.c')
| -rw-r--r-- | src/backend/storage/ipc/spin.c | 37 |
1 files changed, 23 insertions, 14 deletions
diff --git a/src/backend/storage/ipc/spin.c b/src/backend/storage/ipc/spin.c index ed71d79ad9f..b27c1810020 100644 --- a/src/backend/storage/ipc/spin.c +++ b/src/backend/storage/ipc/spin.c @@ -14,7 +14,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/ipc/Attic/spin.c,v 1.28 2001/01/12 21:53:59 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/ipc/Attic/spin.c,v 1.29 2001/01/14 05:08:15 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -25,9 +25,11 @@ #include <sys/sem.h> #endif +#include "miscadmin.h" #include "storage/proc.h" #include "storage/s_lock.h" + /* Probably should move these to an appropriate header file */ extern SPINLOCK ShmemLock; extern SPINLOCK ShmemIndexLock; @@ -145,19 +147,20 @@ SpinAcquire(SPINLOCK lockid) PRINT_SLDEBUG("SpinAcquire", lockid, slckP); /* - * Lock out die() until we exit the critical section protected by the - * spinlock. This ensures that die() will not interrupt manipulations - * of data structures in shared memory. We don't want die() to - * interrupt this routine between S_LOCK and PROC_INCR_SLOCK, either, - * so must do it before acquiring the lock, not after. - */ - START_CRIT_SECTION(); - /* * Acquire the lock, then record that we have done so (for recovery - * in case of elog(ERROR) during the critical section). + * in case of elog(ERROR) during the critical section). Note we assume + * here that S_LOCK will not accept cancel/die interrupts once it has + * acquired the lock. However, interrupts should be accepted while + * waiting, if CritSectionCount is zero. */ S_LOCK(&(slckP->shlock)); PROC_INCR_SLOCK(lockid); + /* + * Lock out cancel/die interrupts until we exit the critical section + * protected by the spinlock. This ensures that interrupts will not + * interfere with manipulations of data structures in shared memory. + */ + START_CRIT_SECTION(); PRINT_SLDEBUG("SpinAcquire/done", lockid, slckP); } @@ -317,10 +320,16 @@ SpinFreeAllSemaphores(void) void SpinAcquire(SPINLOCK lock) { - /* See the TAS() version of this routine for commentary */ - START_CRIT_SECTION(); - IpcSemaphoreLock(SpinLockIds[0], lock); + /* + * See the TAS() version of this routine for primary commentary. + * + * NOTE we must pass interruptOK = false to IpcSemaphoreLock, to ensure + * that a cancel/die interrupt cannot prevent us from recording ownership + * of a lock we have just acquired. + */ + IpcSemaphoreLock(SpinLockIds[0], lock, false); PROC_INCR_SLOCK(lock); + START_CRIT_SECTION(); } /* @@ -338,8 +347,8 @@ SpinRelease(SPINLOCK lock) semval = IpcSemaphoreGetValue(SpinLockIds[0], lock); Assert(semval < 1); - Assert(!MyProc || MyProc->sLocks[lockid] > 0); #endif + Assert(!MyProc || MyProc->sLocks[lockid] > 0); PROC_DECR_SLOCK(lock); IpcSemaphoreUnlock(SpinLockIds[0], lock); END_CRIT_SECTION(); |