From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 12 May 2012 20:36:47 +0000 (-0400)
Subject: Fix WaitLatchOrSocket to handle EOF on socket correctly.
X-Git-Tag: REL9_2_BETA2~96
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=31ad6553646c81f3ce8fccf8aef1a1134a7864c7;p=thirdparty%2Fpostgresql.git

Fix WaitLatchOrSocket to handle EOF on socket correctly.

When using poll(), EOF on a socket is reported with the POLLHUP not
POLLIN flag (at least on Linux).  WaitLatchOrSocket failed to check
this bit, causing it to go into a busy-wait loop if EOF occurs.
We earlier fixed the same mistake in the test for the state of the
postmaster_alive socket, but missed it for the caller-supplied socket.
Fortunately, this error is new in 9.2, since 9.1 only had a select()
based code path not a poll() based one.
---

diff --git a/src/backend/port/unix_latch.c b/src/backend/port/unix_latch.c
index 30d1a488f0a..409beaed8dc 100644
--- a/src/backend/port/unix_latch.c
+++ b/src/backend/port/unix_latch.c
@@ -293,7 +293,7 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
 			result |= WL_TIMEOUT;
 		}
 		if ((wakeEvents & WL_SOCKET_READABLE) &&
-			(pfds[0].revents & POLLIN))
+			(pfds[0].revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
 		{
 			/* data available in socket */
 			result |= WL_SOCKET_READABLE;