Work around gcc 4.6.0 bug

postgresql-gcc-workaround.patch

@@ -0,0 +1,111 @@
+Back-patch upstream patch to cope with a gcc 4.6.0 bug.  This will be
+in PG 9.0.5 and later, but we need it in Fedora *now* because the bug
+breaks WAL replay, thus causing crash recovery failures as well as the
+originally reported symptom of frequent reconnections during standby.
+
+
+commit 45d792f70272ed57b932816562f31c2f79426c2a
+Author: Tom Lane <tgl@sss.pgh.pa.us>
+Date:   Fri Jun 10 17:03:11 2011 -0400
+
+    Work around gcc 4.6.0 bug that breaks WAL replay.
+    
+    ReadRecord's habit of using both direct references to tmpRecPtr and
+    references to *RecPtr (which is pointing at tmpRecPtr) triggers an
+    optimization bug in gcc 4.6.0, which apparently has forgotten about
+    aliasing rules.  Avoid the compiler bug, and make the code more readable
+    to boot, by getting rid of the direct references.  Improve the comments
+    while at it.
+    
+    Back-patch to all supported versions, in case they get built with 4.6.0.
+    
+    Tom Lane, with some cosmetic suggestions from Alex Hunsaker
+
+diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
+index bf8075d..6c18db4 100644
+--- a/src/backend/access/transam/xlog.c
++++ b/src/backend/access/transam/xlog.c
+@@ -3676,23 +3676,32 @@ ReadRecord(XLogRecPtr *RecPtr, int emode, bool fetching_ckpt)
+ 		RecPtr = &tmpRecPtr;
+ 
+ 		/*
+-		 * Align recptr to next page if no more records can fit on the current
+-		 * page.
++		 * RecPtr is pointing to end+1 of the previous WAL record.  We must
++		 * advance it if necessary to where the next record starts.  First,
++		 * align to next page if no more records can fit on the current page.
+ 		 */
+ 		if (XLOG_BLCKSZ - (RecPtr->xrecoff % XLOG_BLCKSZ) < SizeOfXLogRecord)
+-		{
+-			NextLogPage(tmpRecPtr);
+-			/* We will account for page header size below */
+-		}
++			NextLogPage(*RecPtr);
+ 
+-		if (tmpRecPtr.xrecoff >= XLogFileSize)
++		/* Check for crossing of xlog segment boundary */
++		if (RecPtr->xrecoff >= XLogFileSize)
+ 		{
+-			(tmpRecPtr.xlogid)++;
+-			tmpRecPtr.xrecoff = 0;
++			(RecPtr->xlogid)++;
++			RecPtr->xrecoff = 0;
+ 		}
++
++		/*
++		 * If at page start, we must skip over the page header.  But we can't
++		 * do that until we've read in the page, since the header size is
++		 * variable.
++		 */
+ 	}
+ 	else
+ 	{
++		/*
++		 * In this case, the passed-in record pointer should already be
++		 * pointing to a valid record starting position.
++		 */
+ 		if (!XRecOffIsValid(RecPtr->xrecoff))
+ 			ereport(PANIC,
+ 					(errmsg("invalid record offset at %X/%X",
+@@ -3721,11 +3730,13 @@ retry:
+ 	if (targetRecOff == 0)
+ 	{
+ 		/*
+-		 * Can only get here in the continuing-from-prev-page case, because
+-		 * XRecOffIsValid eliminated the zero-page-offset case otherwise. Need
+-		 * to skip over the new page's header.
++		 * At page start, so skip over page header.  The Assert checks that
++		 * we're not scribbling on caller's record pointer; it's OK because we
++		 * can only get here in the continuing-from-prev-record case, since
++		 * XRecOffIsValid rejected the zero-page-offset case otherwise.
+ 		 */
+-		tmpRecPtr.xrecoff += pageHeaderSize;
++		Assert(RecPtr == &tmpRecPtr);
++		RecPtr->xrecoff += pageHeaderSize;
+ 		targetRecOff = pageHeaderSize;
+ 	}
+ 	else if (targetRecOff < pageHeaderSize)
+diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
+index 3f0930f..367de37 100644
+--- a/src/include/access/xlog_internal.h
++++ b/src/include/access/xlog_internal.h
+@@ -154,13 +154,13 @@ typedef XLogLongPageHeaderData *XLogLongPageHeader;
+ /* Align a record pointer to next page */
+ #define NextLogPage(recptr) \
+ 	do {	\
+-		if (recptr.xrecoff % XLOG_BLCKSZ != 0)	\
+-			recptr.xrecoff +=	\
+-				(XLOG_BLCKSZ - recptr.xrecoff % XLOG_BLCKSZ);	\
+-		if (recptr.xrecoff >= XLogFileSize) \
++		if ((recptr).xrecoff % XLOG_BLCKSZ != 0)	\
++			(recptr).xrecoff +=	\
++				(XLOG_BLCKSZ - (recptr).xrecoff % XLOG_BLCKSZ);	\
++		if ((recptr).xrecoff >= XLogFileSize) \
+ 		{	\
+-			(recptr.xlogid)++;	\
+-			recptr.xrecoff = 0; \
++			((recptr).xlogid)++;	\
++			(recptr).xrecoff = 0; \
+ 		}	\
+ 	} while (0)
+ 

postgresql.spec

@@ -54,7 +54,7 @@ Summary: PostgreSQL client programs
 Name: postgresql
 %global majorversion 9.0
 Version: 9.0.4
-Release: 2%{?dist}
+Release: 3%{?dist}
 # The PostgreSQL license is very similar to other MIT licenses, but the OSI
 # recognizes it as an independent license, so we do as well.
 License: PostgreSQL
@@ -85,6 +85,7 @@ Source15: postgresql-bashprofile
 Patch1: rpm-pgsql.patch
 Patch2: postgresql-logging.patch
 Patch3: postgresql-perl-rpath.patch
+Patch4: postgresql-gcc-workaround.patch
 
 BuildRequires: perl(ExtUtils::MakeMaker) glibc-devel bison flex gawk
 BuildRequires: perl(ExtUtils::Embed), perl-devel
@@ -302,6 +303,7 @@ system, including regression tests and benchmarks.
 %patch1 -p1
 %patch2 -p1
 %patch3 -p1
+%patch4 -p1
 
 # We used to run autoconf here, but there's no longer any real need to,
 # since Postgres ships with a reasonably modern configure script.
@@ -820,6 +822,9 @@ rm -rf $RPM_BUILD_ROOT
 %endif
 
 %changelog
+* Fri Jun 10 2011 Tom Lane <tgl@redhat.com> 9.0.4-3
+- Work around gcc 4.6.0 bug (temporary backport from next upstream release)
+
 * Tue May 10 2011 Tom Lane <tgl@redhat.com> 9.0.4-2
 - Add LSB init block to initscript, to ensure sane ordering at system boot
 Resolves: #703215