5 files changed, 40 insertions, 46 deletions

diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index 6fdea3fc2d2..bbbc09b0b5c 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -714,22 +714,6 @@ bgworker_die(SIGNAL_ARGS)
 }
 
 /*
- * Standard SIGUSR1 handler for unconnected workers
- *
- * Here, we want to make sure an unconnected worker will at least heed
- * latch activity.
- */
-static void
-bgworker_sigusr1_handler(SIGNAL_ARGS)
-{
-	int			save_errno = errno;
-
-	latch_sigusr1_handler();
-
-	errno = save_errno;
-}
-
-/*
  * Start a new background worker
  *
  * This is the main entry point for background worker, to be called from
@@ -759,6 +743,7 @@ StartBackgroundWorker(void)
 	 */
 	if ((worker->bgw_flags & BGWORKER_SHMEM_ACCESS) == 0)
 	{
+		ShutdownLatchSupport();
 		dsm_detach_all();
 		PGSharedMemoryDetach();
 	}
@@ -786,7 +771,7 @@ StartBackgroundWorker(void)
 	else
 	{
 		pqsignal(SIGINT, SIG_IGN);
-		pqsignal(SIGUSR1, bgworker_sigusr1_handler);
+		pqsignal(SIGUSR1, SIG_IGN);
 		pqsignal(SIGFPE, SIG_IGN);
 	}
 	pqsignal(SIGTERM, bgworker_die);
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 9568dafbe24..3f1ce135a85 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -656,6 +656,10 @@ PostmasterMain(int argc, char *argv[])
 	pqsignal_pm(SIGUSR2, dummy_handler);	/* unused, reserve for children */
 	pqsignal_pm(SIGCHLD, reaper);	/* handle child termination */
 
+#ifdef SIGURG
+	pqsignal_pm(SIGURG, SIG_IGN);	/* ignored */
+#endif
+
 	/*
 	 * No other place in Postgres should touch SIGTTIN/SIGTTOU handling.  We
 	 * ignore those signals in a postmaster environment, so that there is no
diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c
index eacf8d51ea0..0f274280e65 100644
--- a/src/backend/storage/ipc/latch.c
+++ b/src/backend/storage/ipc/latch.c
@@ -16,7 +16,7 @@
  *
  * When SetLatch is called from the same process that owns the latch,
  * SetLatch writes the byte directly to the pipe. If it's owned by another
- * process, SIGUSR1 is sent and the signal handler in the waiting process
+ * process, SIGURG is sent and the signal handler in the waiting process
  * writes the byte to the pipe on behalf of the signaling process.
  *
  * The Windows implementation uses Windows events that are inherited by all
@@ -148,6 +148,7 @@ static int	selfpipe_writefd = -1;
 static int	selfpipe_owner_pid = 0;
 
 /* Private function prototypes */
+static void latch_sigurg_handler(SIGNAL_ARGS);
 static void sendSelfPipeByte(void);
 static void drainSelfPipe(void);
 #endif							/* WIN32 */
@@ -244,6 +245,8 @@ InitializeLatchSupport(void)
 	/* Tell fd.c about these two long-lived FDs */
 	ReserveExternalFD();
 	ReserveExternalFD();
+
+	pqsignal(SIGURG, latch_sigurg_handler);
 #else
 	/* currently, nothing to do here for Windows */
 #endif
@@ -267,6 +270,24 @@ InitializeLatchWaitSet(void)
 	Assert(latch_pos == LatchWaitSetLatchPos);
 }
 
+void
+ShutdownLatchSupport(void)
+{
+	pqsignal(SIGURG, SIG_IGN);
+
+	if (LatchWaitSet)
+	{
+		FreeWaitEventSet(LatchWaitSet);
+		LatchWaitSet = NULL;
+	}
+
+	close(selfpipe_readfd);
+	close(selfpipe_writefd);
+	selfpipe_readfd = -1;
+	selfpipe_writefd = -1;
+	selfpipe_owner_pid = InvalidPid;
+}
+
 /*
  * Initialize a process-local latch.
  */
@@ -335,10 +356,6 @@ InitSharedLatch(Latch *latch)
  * any sort of locking here, meaning that we could fail to detect the error
  * if two processes try to own the same latch at about the same time.  If
  * there is any risk of that, caller must provide an interlock to prevent it.
- *
- * In any process that calls OwnLatch(), make sure that
- * latch_sigusr1_handler() is called from the SIGUSR1 signal handler,
- * as shared latches use SIGUSR1 for inter-process communication.
  */
 void
 OwnLatch(Latch *latch)
@@ -562,7 +579,7 @@ SetLatch(Latch *latch)
 			sendSelfPipeByte();
 	}
 	else
-		kill(owner_pid, SIGUSR1);
+		kill(owner_pid, SIGURG);
 #else
 
 	/*
@@ -1266,7 +1283,7 @@ WaitEventSetWait(WaitEventSet *set, long timeout,
 		 * the pipe-buffer fill up we're still ok, because the pipe is in
 		 * nonblocking mode. It's unlikely for that to happen, because the
 		 * self pipe isn't filled unless we're blocking (waiting = true), or
-		 * from inside a signal handler in latch_sigusr1_handler().
+		 * from inside a signal handler in latch_sigurg_handler().
 		 *
 		 * On windows, we'll also notice if there's a pending event for the
 		 * latch when blocking, but there's no danger of anything filling up,
@@ -1934,22 +1951,21 @@ WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
 }
 #endif
 
+#ifndef WIN32
 /*
- * SetLatch uses SIGUSR1 to wake up the process waiting on the latch.
- *
- * Wake up WaitLatch, if we're waiting.  (We might not be, since SIGUSR1 is
- * overloaded for multiple purposes; or we might not have reached WaitLatch
- * yet, in which case we don't need to fill the pipe either.)
+ * SetLatch uses SIGURG to wake up the process waiting on the latch.
  *
- * NB: when calling this in a signal handler, be sure to save and restore
- * errno around it.
+ * Wake up WaitLatch, if we're waiting.
  */
-#ifndef WIN32
-void
-latch_sigusr1_handler(void)
+static void
+latch_sigurg_handler(SIGNAL_ARGS)
 {
+	int			save_errno = errno;
+
 	if (waiting)
 		sendSelfPipeByte();
+
+	errno = save_errno;
 }
 #endif							/* !WIN32 */
 
diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c
index c43cdd685b4..ed97f4a3e97 100644
--- a/src/backend/storage/ipc/procsignal.c
+++ b/src/backend/storage/ipc/procsignal.c
@@ -688,7 +688,5 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
 
 	SetLatch(MyLatch);
 
-	latch_sigusr1_handler();
-
 	errno = save_errno;
 }
diff --git a/src/include/storage/latch.h b/src/include/storage/latch.h
index 393591be03c..9e94fcaec24 100644
--- a/src/include/storage/latch.h
+++ b/src/include/storage/latch.h
@@ -163,6 +163,7 @@ extern void OwnLatch(Latch *latch);
 extern void DisownLatch(Latch *latch);
 extern void SetLatch(Latch *latch);
 extern void ResetLatch(Latch *latch);
+extern void ShutdownLatchSupport(void);
 
 extern WaitEventSet *CreateWaitEventSet(MemoryContext context, int nevents);
 extern void FreeWaitEventSet(WaitEventSet *set);
@@ -179,14 +180,4 @@ extern int	WaitLatchOrSocket(Latch *latch, int wakeEvents,
 							  pgsocket sock, long timeout, uint32 wait_event_info);
 extern void InitializeLatchWaitSet(void);
 
-/*
- * Unix implementation uses SIGUSR1 for inter-process signaling.
- * Win32 doesn't need this.
- */
-#ifndef WIN32
-extern void latch_sigusr1_handler(void);
-#else
-#define latch_sigusr1_handler()  ((void) 0)
-#endif
-
 #endif							/* LATCH_H */