1 files changed, 25 insertions, 17 deletions

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);