diff options
| -rw-r--r-- | src/backend/storage/ipc/procsignal.c | 9 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/proc.c | 42 |
2 files changed, 33 insertions, 18 deletions
diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c index 6ebabce72f7..6526b2688a8 100644 --- a/src/backend/storage/ipc/procsignal.c +++ b/src/backend/storage/ipc/procsignal.c @@ -149,6 +149,13 @@ CleanupProcSignalState(int status, Datum arg) slot = &ProcSignalSlots[pss_idx - 1]; Assert(slot == MyProcSignalSlot); + /* + * Clear MyProcSignalSlot, so that a SIGUSR1 received after this point + * won't try to access it after it's no longer ours (and perhaps even + * after we've unmapped the shared memory segment). + */ + MyProcSignalSlot = NULL; + /* sanity check */ if (slot->pss_pid != MyProcPid) { @@ -285,7 +292,7 @@ procsignal_sigusr1_handler(SIGNAL_ARGS) if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN)) RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN); - if (set_latch_on_sigusr1) + if (set_latch_on_sigusr1 && MyProc != NULL) SetLatch(&MyProc->procLatch); latch_sigusr1_handler(); diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index 1a683b83361..9d32f9405d5 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -773,6 +773,7 @@ ProcKill(int code, Datum arg) { /* use volatile pointer to prevent code rearrangement */ volatile PROC_HDR *procglobal = ProcGlobal; + PGPROC *proc; Assert(MyProc != NULL); @@ -797,31 +798,34 @@ ProcKill(int code, Datum arg) */ LWLockReleaseAll(); - /* Release ownership of the process's latch, too */ - DisownLatch(&MyProc->procLatch); + /* + * Clear MyProc first; then disown the process latch. This is so that + * signal handlers won't try to clear the process latch after it's no + * longer ours. + */ + proc = MyProc; + MyProc = NULL; + DisownLatch(&proc->procLatch); SpinLockAcquire(ProcStructLock); /* Return PGPROC structure (and semaphore) to appropriate freelist */ if (IsAnyAutoVacuumProcess()) { - MyProc->links.next = (SHM_QUEUE *) procglobal->autovacFreeProcs; - procglobal->autovacFreeProcs = MyProc; + proc->links.next = (SHM_QUEUE *) procglobal->autovacFreeProcs; + procglobal->autovacFreeProcs = proc; } else if (IsBackgroundWorker) { - MyProc->links.next = (SHM_QUEUE *) procglobal->bgworkerFreeProcs; - procglobal->bgworkerFreeProcs = MyProc; + proc->links.next = (SHM_QUEUE *) procglobal->bgworkerFreeProcs; + procglobal->bgworkerFreeProcs = proc; } else { - MyProc->links.next = (SHM_QUEUE *) procglobal->freeProcs; - procglobal->freeProcs = MyProc; + proc->links.next = (SHM_QUEUE *) procglobal->freeProcs; + procglobal->freeProcs = proc; } - /* PGPROC struct isn't mine anymore */ - MyProc = NULL; - /* Update shared estimate of spins_per_delay */ procglobal->spins_per_delay = update_spins_per_delay(procglobal->spins_per_delay); @@ -850,6 +854,7 @@ AuxiliaryProcKill(int code, Datum arg) { int proctype = DatumGetInt32(arg); PGPROC *auxproc PG_USED_FOR_ASSERTS_ONLY; + PGPROC *proc; Assert(proctype >= 0 && proctype < NUM_AUXILIARY_PROCS); @@ -860,16 +865,19 @@ AuxiliaryProcKill(int code, Datum arg) /* Release any LW locks I am holding (see notes above) */ LWLockReleaseAll(); - /* Release ownership of the process's latch, too */ - DisownLatch(&MyProc->procLatch); + /* + * Clear MyProc first; then disown the process latch. This is so that + * signal handlers won't try to clear the process latch after it's no + * longer ours. + */ + proc = MyProc; + MyProc = NULL; + DisownLatch(&proc->procLatch); SpinLockAcquire(ProcStructLock); /* Mark auxiliary proc no longer in use */ - MyProc->pid = 0; - - /* PGPROC struct isn't mine anymore */ - MyProc = NULL; + proc->pid = 0; /* Update shared estimate of spins_per_delay */ ProcGlobal->spins_per_delay = update_spins_per_delay(ProcGlobal->spins_per_delay); |