From 10538a8f9e2e718a47633ac5a6e90415a2c3f5f1 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Fri, 22 Jul 2016 21:58:18 +0000
Subject: [PATCH 01/16] net/http: fix potential for-select spin with closed
 Context.Done channel

Noticed when investigating a separate issue.

No external bug report or repro yet.

Change-Id: I8a1641a43163f22b09accd3beb25dd9e2a68a238
Reviewed-on: https://go-review.googlesource.com/25152
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
---
 src/net/http/transport.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/net/http/transport.go b/src/net/http/transport.go
index 9164d0d827..a51f1d0658 100644
--- a/src/net/http/transport.go
+++ b/src/net/http/transport.go
@@ -1784,6 +1784,7 @@ func (pc *persistConn) roundTrip(req *transportRequest) (resp *Response, err err
 	var re responseAndError
 	var respHeaderTimer <-chan time.Time
 	cancelChan := req.Request.Cancel
+	ctxDoneChan := req.Context().Done()
 WaitResponse:
 	for {
 		testHookWaitResLoop()
@@ -1815,9 +1816,11 @@ WaitResponse:
 		case <-cancelChan:
 			pc.t.CancelRequest(req.Request)
 			cancelChan = nil
-		case <-req.Context().Done():
+			ctxDoneChan = nil
+		case <-ctxDoneChan:
 			pc.t.CancelRequest(req.Request)
 			cancelChan = nil
+			ctxDoneChan = nil
 		}
 	}
 

From d0256118de0b397494a3f4ca6d2e1e889b8c114e Mon Sep 17 00:00:00 2001
From: Joe Tsai <joetsai@digital-static.net>
Date: Mon, 25 Jul 2016 15:49:35 -0700
Subject: [PATCH 02/16] compress/flate: document HuffmanOnly

Fixes #16489

Change-Id: I13e2ed6de59102f977566de637d8d09b4e541980
Reviewed-on: https://go-review.googlesource.com/25200
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---
 src/compress/flate/deflate.go | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/compress/flate/deflate.go b/src/compress/flate/deflate.go
index 8a085ba347..3e4dc7b57e 100644
--- a/src/compress/flate/deflate.go
+++ b/src/compress/flate/deflate.go
@@ -15,7 +15,17 @@ const (
 	BestSpeed          = 1
 	BestCompression    = 9
 	DefaultCompression = -1
-	HuffmanOnly        = -2 // Disables match search and only does Huffman entropy reduction.
+
+	// HuffmanOnly disables Lempel-Ziv match searching and only performs Huffman
+	// entropy encoding. This mode is useful in compressing data that has
+	// already been compressed with an LZ style algorithm (e.g. Snappy or LZ4)
+	// that lacks an entropy encoder. Compression gains are achieved when
+	// certain bytes in the input stream occur more frequently than others.
+	//
+	// Note that HuffmanOnly produces a compressed output that is
+	// RFC 1951 compliant. That is, any valid DEFLATE decompressor will
+	// continue to be able to decompress this output.
+	HuffmanOnly = -2
 )
 
 const (
@@ -644,7 +654,6 @@ func (d *compressor) close() error {
 // a very fast compression for all types of input, but sacrificing considerable
 // compression efficiency.
 //
-//
 // If level is in the range [-2, 9] then the error returned will be nil.
 // Otherwise the error returned will be non-nil.
 func NewWriter(w io.Writer, level int) (*Writer, error) {

From 67f799c42cbe5fa667dbad0139a98728624cbf4b Mon Sep 17 00:00:00 2001
From: Michael Munday <munday@ca.ibm.com>
Date: Sat, 23 Jul 2016 23:27:25 -0400
Subject: [PATCH 03/16] doc: add s390x information to asm.html

Fixes #16362

Change-Id: I676718a1149ed2f3ff80cb031e25de7043805399
Reviewed-on: https://go-review.googlesource.com/25157
Reviewed-by: Rob Pike <r@golang.org>
---
 doc/asm.html | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/doc/asm.html b/doc/asm.html
index 392af174c2..3e03c548fd 100644
--- a/doc/asm.html
+++ b/doc/asm.html
@@ -780,6 +780,64 @@ mode as on the x86, but the only scale allowed is <code>1</code>.
 
 </ul>
 
+<h3 id="s390x">IBM z/Architecture, a.k.a. s390x</h3>
+
+<p>
+The registers <code>R10</code> and <code>R11</code> are reserved.
+The assembler uses them to hold temporary values when assembling some instructions.
+</p>
+
+<p>
+<code>R13</code> points to the <code>g</code> (goroutine) structure.
+This register must be referred to as <code>g</code>; the name <code>R13</code> is not recognized.
+</p>
+
+<p>
+<code>R15</code> points to the stack frame and should typically only be accessed using the
+virtual registers <code>SP</code> and <code>FP</code>.
+</p>
+
+<p>
+Load- and store-multiple instructions operate on a range of registers.
+The range of registers is specified by a start register and an end register.
+For example, <code>LMG</code> <code>(R9),</code> <code>R5,</code> <code>R7</code> would load
+<code>R5</code>, <code>R6</code> and <code>R7</code> with the 64-bit values at
+<code>0(R9)</code>, <code>8(R9)</code> and <code>16(R9)</code> respectively.
+</p>
+
+<p>
+Storage-and-storage instructions such as <code>MVC</code> and <code>XC</code> are written
+with the length as the first argument.
+For example, <code>XC</code> <code>$8,</code> <code>(R9),</code> <code>(R9)</code> would clear
+eight bytes at the address specified in <code>R9</code>.
+</p>
+
+<p>
+If a vector instruction takes a length or an index as an argument then it will be the
+first argument.
+For example, <code>VLEIF</code> <code>$1,</code> <code>$16,</code> <code>V2</code> will load
+the value sixteen into index one of <code>V2</code>.
+Care should be taken when using vector instructions to ensure that they are available at
+runtime.
+To use vector instructions a machine must have both the vector facility (bit 129 in the
+facility list) and kernel support.
+Without kernel support a vector instruction will have no effect (it will be equivalent
+to a <code>NOP</code> instruction).
+</p>
+
+<p>
+Addressing modes:
+</p>
+
+<ul>
+
+<li>
+<code>(R5)(R6*1)</code>: The location at <code>R5</code> plus <code>R6</code>.
+It is a scaled mode as on the x86, but the only scale allowed is <code>1</code>.
+</li>
+
+</ul>
+
 <h3 id="unsupported_opcodes">Unsupported opcodes</h3>
 
 <p>

From ea2376fcea0be75c856ebd199c0ad0f98192d406 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Fri, 22 Jul 2016 22:51:05 +0000
Subject: [PATCH 04/16] net/http: make Transport.RoundTrip return raw Conn.Read
 error on peek failure

From at least Go 1.4 to Go 1.6, Transport.RoundTrip would return the
error value from net.Conn.Read directly when the initial Read (1 byte
Peek) failed while reading the HTTP response, if a request was
outstanding. While never a documented or tested promise, Go 1.7 changed the
behavior (starting at https://golang.org/cl/23160).

This restores the old behavior and adds a test (but no documentation
promises yet) while keeping the fix for spammy logging reported in #15446.

This looks larger than it is: it just changes errServerClosedConn from
a variable to a type, where the type preserves the underlying
net.Conn.Read error, for unwrapping later in Transport.RoundTrip.

Fixes #16465

Change-Id: I6fa018991221e93c0cfe3e4129cb168fbd98bd27
Reviewed-on: https://go-review.googlesource.com/25153
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---
 src/net/http/transport.go               | 47 +++++++++++++++++++++----
 src/net/http/transport_internal_test.go |  9 +++--
 src/net/http/transport_test.go          | 39 ++++++++++++++++++++
 3 files changed, 87 insertions(+), 8 deletions(-)

diff --git a/src/net/http/transport.go b/src/net/http/transport.go
index a51f1d0658..009f3c5b6a 100644
--- a/src/net/http/transport.go
+++ b/src/net/http/transport.go
@@ -383,6 +383,11 @@ func (t *Transport) RoundTrip(req *Request) (*Response, error) {
 			return resp, nil
 		}
 		if !pconn.shouldRetryRequest(req, err) {
+			// Issue 16465: return underlying net.Conn.Read error from peek,
+			// as we've historically done.
+			if e, ok := err.(transportReadFromServerError); ok {
+				err = e.err
+			}
 			return nil, err
 		}
 		testHookRoundTripRetried()
@@ -415,11 +420,19 @@ func (pc *persistConn) shouldRetryRequest(req *Request, err error) bool {
 		// first, per golang.org/issue/15723
 		return false
 	}
-	if _, ok := err.(nothingWrittenError); ok {
+	switch err.(type) {
+	case nothingWrittenError:
 		// We never wrote anything, so it's safe to retry.
 		return true
+	case transportReadFromServerError:
+		// We got some non-EOF net.Conn.Read failure reading
+		// the 1st response byte from the server.
+		return true
 	}
-	if err == errServerClosedIdle || err == errServerClosedConn {
+	if err == errServerClosedIdle {
+		// The server replied with io.EOF while we were trying to
+		// read the response. Probably an unfortunately keep-alive
+		// timeout, just as the client was writing a request.
 		return true
 	}
 	return false // conservatively
@@ -566,10 +579,25 @@ var (
 	errCloseIdleConns     = errors.New("http: CloseIdleConnections called")
 	errReadLoopExiting    = errors.New("http: persistConn.readLoop exiting")
 	errServerClosedIdle   = errors.New("http: server closed idle connection")
-	errServerClosedConn   = errors.New("http: server closed connection")
 	errIdleConnTimeout    = errors.New("http: idle connection timeout")
 )
 
+// transportReadFromServerError is used by Transport.readLoop when the
+// 1 byte peek read fails and we're actually anticipating a response.
+// Usually this is just due to the inherent keep-alive shut down race,
+// where the server closed the connection at the same time the client
+// wrote. The underlying err field is usually io.EOF or some
+// ECONNRESET sort of thing which varies by platform. But it might be
+// the user's custom net.Conn.Read error too, so we carry it along for
+// them to return from Transport.RoundTrip.
+type transportReadFromServerError struct {
+	err error
+}
+
+func (e transportReadFromServerError) Error() string {
+	return fmt.Sprintf("net/http: Transport failed to read from server: %v", e.err)
+}
+
 func (t *Transport) putOrCloseIdleConn(pconn *persistConn) {
 	if err := t.tryPutIdleConn(pconn); err != nil {
 		pconn.close(err)
@@ -1293,7 +1321,10 @@ func (pc *persistConn) mapRoundTripErrorFromReadLoop(startBytesWritten int64, er
 	if pc.isCanceled() {
 		return errRequestCanceled
 	}
-	if err == errServerClosedIdle || err == errServerClosedConn {
+	if err == errServerClosedIdle {
+		return err
+	}
+	if _, ok := err.(transportReadFromServerError); ok {
 		return err
 	}
 	if pc.isBroken() {
@@ -1314,7 +1345,11 @@ func (pc *persistConn) mapRoundTripErrorAfterClosed(startBytesWritten int64) err
 		return errRequestCanceled
 	}
 	err := pc.closed
-	if err == errServerClosedIdle || err == errServerClosedConn {
+	if err == errServerClosedIdle {
+		// Don't decorate
+		return err
+	}
+	if _, ok := err.(transportReadFromServerError); ok {
 		// Don't decorate
 		return err
 	}
@@ -1383,7 +1418,7 @@ func (pc *persistConn) readLoop() {
 		if err == nil {
 			resp, err = pc.readResponse(rc, trace)
 		} else {
-			err = errServerClosedConn
+			err = transportReadFromServerError{err}
 			closeErr = err
 		}
 
diff --git a/src/net/http/transport_internal_test.go b/src/net/http/transport_internal_test.go
index a157d90630..a05ca6ed0d 100644
--- a/src/net/http/transport_internal_test.go
+++ b/src/net/http/transport_internal_test.go
@@ -46,17 +46,22 @@ func TestTransportPersistConnReadLoopEOF(t *testing.T) {
 	conn.Close() // simulate the server hanging up on the client
 
 	_, err = pc.roundTrip(treq)
-	if err != errServerClosedConn && err != errServerClosedIdle {
+	if !isTransportReadFromServerError(err) && err != errServerClosedIdle {
 		t.Fatalf("roundTrip = %#v, %v; want errServerClosedConn or errServerClosedIdle", err, err)
 	}
 
 	<-pc.closech
 	err = pc.closed
-	if err != errServerClosedConn && err != errServerClosedIdle {
+	if !isTransportReadFromServerError(err) && err != errServerClosedIdle {
 		t.Fatalf("pc.closed = %#v, %v; want errServerClosedConn or errServerClosedIdle", err, err)
 	}
 }
 
+func isTransportReadFromServerError(err error) bool {
+	_, ok := err.(transportReadFromServerError)
+	return ok
+}
+
 func newLocalListener(t *testing.T) net.Listener {
 	ln, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {
diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index 72b98f16d7..749d4530b8 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -3511,6 +3511,45 @@ func TestTransportIdleConnTimeout(t *testing.T) {
 	}
 }
 
+type funcConn struct {
+	net.Conn
+	read  func([]byte) (int, error)
+	write func([]byte) (int, error)
+}
+
+func (c funcConn) Read(p []byte) (int, error)  { return c.read(p) }
+func (c funcConn) Write(p []byte) (int, error) { return c.write(p) }
+func (c funcConn) Close() error                { return nil }
+
+// Issue 16465: Transport.RoundTrip should return the raw net.Conn.Read error from Peek
+// back to the caller.
+func TestTransportReturnsPeekError(t *testing.T) {
+	errValue := errors.New("specific error value")
+
+	wrote := make(chan struct{})
+	var wroteOnce sync.Once
+
+	tr := &Transport{
+		Dial: func(network, addr string) (net.Conn, error) {
+			c := funcConn{
+				read: func([]byte) (int, error) {
+					<-wrote
+					return 0, errValue
+				},
+				write: func(p []byte) (int, error) {
+					wroteOnce.Do(func() { close(wrote) })
+					return len(p), nil
+				},
+			}
+			return c, nil
+		},
+	}
+	_, err := tr.RoundTrip(httptest.NewRequest("GET", "http://fake.tld/", nil))
+	if err != errValue {
+		t.Errorf("error = %#v; want %v", err, errValue)
+	}
+}
+
 var errFakeRoundTrip = errors.New("fake roundtrip")
 
 type funcRoundTripper func()

From 887606114902bd58c3838767ac2b66dadba27e5e Mon Sep 17 00:00:00 2001
From: Jack Lindamood <jlindamo@justin.tv>
Date: Fri, 15 Jul 2016 13:28:27 -0700
Subject: [PATCH 05/16] context: add test for WithDeadline in the past

Adds a test case for calling context.WithDeadline() where the deadline
exists in the past.  This change increases the code coverage of the
context package.

Change-Id: Ib486bf6157e779fafd9dab2b7364cdb5a06be36e
Reviewed-on: https://go-review.googlesource.com/25007
Reviewed-by: Sameer Ajmani <sameer@golang.org>
Run-TryBot: Sameer Ajmani <sameer@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---
 src/context/context_test.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/context/context_test.go b/src/context/context_test.go
index 90e78e57ec..cf182110fb 100644
--- a/src/context/context_test.go
+++ b/src/context/context_test.go
@@ -255,6 +255,12 @@ func TestDeadline(t *testing.T) {
 	o = otherContext{c}
 	c, _ = WithDeadline(o, time.Now().Add(4*time.Second))
 	testDeadline(c, "WithDeadline+otherContext+WithDeadline", 2*time.Second, t)
+
+	c, _ = WithDeadline(Background(), time.Now().Add(-time.Millisecond))
+	testDeadline(c, "WithDeadline+inthepast", time.Second, t)
+
+	c, _ = WithDeadline(Background(), time.Now())
+	testDeadline(c, "WithDeadline+now", time.Second, t)
 }
 
 func TestTimeout(t *testing.T) {

From ff60da6962f71871fac3dd6a5406686ea92de8dc Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Tue, 26 Jul 2016 16:55:40 +0200
Subject: [PATCH 06/16] crypto/x509: use Go 1.6 implementation for
 FetchPEMRoots for OS X 10.8

Conservative fix for the OS X 10.8 crash. We can unify them back together
during the Go 1.8 dev cycle.

Fixes #16473

Change-Id: If07228deb2be36093dd324b3b3bcb31c23a95035
Reviewed-on: https://go-review.googlesource.com/25233
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
---
 src/crypto/x509/root_cgo_darwin.go | 46 ++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/src/crypto/x509/root_cgo_darwin.go b/src/crypto/x509/root_cgo_darwin.go
index 0e2fb357ee..83f83d8c16 100644
--- a/src/crypto/x509/root_cgo_darwin.go
+++ b/src/crypto/x509/root_cgo_darwin.go
@@ -13,6 +13,48 @@ package x509
 #include <CoreFoundation/CoreFoundation.h>
 #include <Security/Security.h>
 
+// FetchPEMRoots_MountainLion is the version of FetchPEMRoots from Go 1.6
+// which still works on OS X 10.8 (Mountain Lion).
+// It lacks support for admin & user cert domains.
+// See golang.org/issue/16473
+int FetchPEMRoots_MountainLion(CFDataRef *pemRoots) {
+	if (pemRoots == NULL) {
+		return -1;
+	}
+	CFArrayRef certs = NULL;
+	OSStatus err = SecTrustCopyAnchorCertificates(&certs);
+	if (err != noErr) {
+		return -1;
+	}
+	CFMutableDataRef combinedData = CFDataCreateMutable(kCFAllocatorDefault, 0);
+	int i, ncerts = CFArrayGetCount(certs);
+	for (i = 0; i < ncerts; i++) {
+		CFDataRef data = NULL;
+		SecCertificateRef cert = (SecCertificateRef)CFArrayGetValueAtIndex(certs, i);
+		if (cert == NULL) {
+			continue;
+		}
+		// Note: SecKeychainItemExport is deprecated as of 10.7 in favor of SecItemExport.
+		// Once we support weak imports via cgo we should prefer that, and fall back to this
+		// for older systems.
+		err = SecKeychainItemExport(cert, kSecFormatX509Cert, kSecItemPemArmour, NULL, &data);
+		if (err != noErr) {
+			continue;
+		}
+		if (data != NULL) {
+			CFDataAppendBytes(combinedData, CFDataGetBytePtr(data), CFDataGetLength(data));
+			CFRelease(data);
+		}
+	}
+	CFRelease(certs);
+	*pemRoots = combinedData;
+	return 0;
+}
+
+#ifndef kCFCoreFoundationVersionNumber10_9
+#define kCFCoreFoundationVersionNumber10_9      855.11
+#endif
+
 // FetchPEMRoots fetches the system's list of trusted X.509 root certificates.
 //
 // On success it returns 0 and fills pemRoots with a CFDataRef that contains the extracted root
@@ -21,6 +63,10 @@ package x509
 // Note: The CFDataRef returned in pemRoots must be released (using CFRelease) after
 // we've consumed its content.
 int FetchPEMRoots(CFDataRef *pemRoots) {
+	if (kCFCoreFoundationVersionNumber < kCFCoreFoundationVersionNumber10_9) {
+		return FetchPEMRoots_MountainLion(pemRoots);
+	}
+
 	// Get certificates from all domains, not just System, this lets
 	// the user add CAs to their "login" keychain, and Admins to add
 	// to the "System" keychain

From b11fff3886705bd98aec4923f43216ed8e13cb1a Mon Sep 17 00:00:00 2001
From: Austin Clements <austin@google.com>
Date: Mon, 25 Jul 2016 13:41:07 -0400
Subject: [PATCH 07/16] runtime/pprof: document use of pprof package

Currently the pprof package gives almost no guidance for how to use it
and, despite the standard boilerplate used to create CPU and memory
profiles, this boilerplate appears nowhere in the pprof documentation.

Update the pprof package documentation to give the standard
boilerplate in a form people can copy, paste, and tweak. This
boilerplate is based on rsc's 2011 blog post on profiling Go programs
at https://blog.golang.org/profiling-go-programs, which is where I
always go when I need to copy-paste the boilerplate.

Change-Id: I74021e494ea4dcc6b56d6fb5e59829ad4bb7b0be
Reviewed-on: https://go-review.googlesource.com/25182
Reviewed-by: Rick Hudson <rlh@golang.org>
---
 src/runtime/pprof/pprof.go | 63 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/src/runtime/pprof/pprof.go b/src/runtime/pprof/pprof.go
index b7c41f13de..25f7ed6eb1 100644
--- a/src/runtime/pprof/pprof.go
+++ b/src/runtime/pprof/pprof.go
@@ -4,8 +4,69 @@
 
 // Package pprof writes runtime profiling data in the format expected
 // by the pprof visualization tool.
+//
+// Profiling a Go program
+//
+// The first step to profiling a Go program is to enable profiling.
+// Support for profiling benchmarks built with the standard testing
+// package is built into go test. For example, the following command
+// runs benchmarks in the current directory and writes the CPU and
+// memory profiles to cpu.prof and mem.prof:
+//
+//     go test -cpuprofile cpu.prof -memprofile mem.prof -bench .
+//
+// To add equivalent profiling support to a standalone program, add
+// code like the following to your main function:
+//
+//    var cpuprofile = flag.String("cpuprofile", "", "write cpu profile `file`")
+//    var memprofile = flag.String("memprofile", "", "write memory profile to `file`")
+//
+//    func main() {
+//        flag.Parse()
+//        if *cpuprofile != "" {
+//            f, err := os.Create(*cpuprofile)
+//            if err != nil {
+//                log.Fatal("could not create CPU profile: ", err)
+//            }
+//            if err := pprof.StartCPUProfile(f); err != nil {
+//                log.Fatal("could not start CPU profile: ", err)
+//            }
+//            defer pprof.StopCPUProfile()
+//        }
+//        ...
+//        if *memprofile != "" {
+//            f, err := os.Create(*memprofile)
+//            if err != nil {
+//                log.Fatal("could not create memory profile: ", err)
+//            }
+//            runtime.GC() // get up-to-date statistics
+//            if err := pprof.WriteHeapProfile(f); err != nil {
+//                log.Fatal("could not write memory profile: ", err)
+//            }
+//            f.Close()
+//        }
+//    }
+//
+// There is also a standard HTTP interface to profiling data. Adding
+// the following line will install handlers under the /debug/pprof/
+// URL to download live profiles:
+//
+//    import _ "net/http/pprof"
+//
+// See the net/http/pprof package for more details.
+//
+// Profiles can then be visualized with the pprof tool:
+//
+//    go tool pprof cpu.prof
+//
+// There are many commands available from the pprof command line.
+// Commonly used commands include "top", which prints a summary of the
+// top program hot-spots, and "web", which opens an interactive graph
+// of hot-spots and their call graphs. Use "help" for information on
+// all pprof commands.
+//
 // For more information about pprof, see
-// http://github.com/google/pprof/.
+// https://github.com/google/pprof/blob/master/doc/pprof.md.
 package pprof
 
 import (

From 66b47431cba75ce23630e17c1a3aa000e7b33d06 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Wed, 27 Jul 2016 00:17:38 +0200
Subject: [PATCH 08/16] net/http: update bundled http2

Updates x/net/http2 to git rev 6a513af for:

  http2: return flow control for closed streams
  https://golang.org/cl/25231

  http2: make Transport prefer HTTP response header recv before body write error
  https://golang.org/cl/24984

  http2: make Transport treat "Connection: close" the same as Request.Close
  https://golang.org/cl/24982

Fixes golang/go#16481

Change-Id: Iaddb166387ca2df1cfbbf09a166f8605578bec49
Reviewed-on: https://go-review.googlesource.com/25282
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
---
 src/net/http/h2_bundle.go | 121 ++++++++++++++++++++++++++++++--------
 1 file changed, 95 insertions(+), 26 deletions(-)

diff --git a/src/net/http/h2_bundle.go b/src/net/http/h2_bundle.go
index 47e5f577e6..a117897bcf 100644
--- a/src/net/http/h2_bundle.go
+++ b/src/net/http/h2_bundle.go
@@ -85,7 +85,16 @@ const (
 	http2noDialOnMiss = false
 )
 
-func (p *http2clientConnPool) getClientConn(_ *Request, addr string, dialOnMiss bool) (*http2ClientConn, error) {
+func (p *http2clientConnPool) getClientConn(req *Request, addr string, dialOnMiss bool) (*http2ClientConn, error) {
+	if http2isConnectionCloseRequest(req) && dialOnMiss {
+		// It gets its own connection.
+		const singleUse = true
+		cc, err := p.t.dialClientConn(addr, singleUse)
+		if err != nil {
+			return nil, err
+		}
+		return cc, nil
+	}
 	p.mu.Lock()
 	for _, cc := range p.conns[addr] {
 		if cc.CanTakeNewRequest() {
@@ -128,7 +137,8 @@ func (p *http2clientConnPool) getStartDialLocked(addr string) *http2dialCall {
 
 // run in its own goroutine.
 func (c *http2dialCall) dial(addr string) {
-	c.res, c.err = c.p.t.dialClientConn(addr)
+	const singleUse = false // shared conn
+	c.res, c.err = c.p.t.dialClientConn(addr, singleUse)
 	close(c.done)
 
 	c.p.mu.Lock()
@@ -3803,6 +3813,9 @@ func (sc *http2serverConn) closeStream(st *http2stream, err error) {
 	}
 	delete(sc.streams, st.id)
 	if p := st.body; p != nil {
+
+		sc.sendWindowUpdate(nil, p.Len())
+
 		p.CloseWithError(err)
 	}
 	st.cw.Close()
@@ -3879,17 +3892,24 @@ func (sc *http2serverConn) processSettingInitialWindowSize(val uint32) error {
 
 func (sc *http2serverConn) processData(f *http2DataFrame) error {
 	sc.serveG.check()
+	data := f.Data()
 
 	id := f.Header().StreamID
 	st, ok := sc.streams[id]
 	if !ok || st.state != http2stateOpen || st.gotTrailerHeader {
 
+		if int(sc.inflow.available()) < len(data) {
+			return http2StreamError{id, http2ErrCodeFlowControl}
+		}
+
+		sc.inflow.take(int32(len(data)))
+		sc.sendWindowUpdate(nil, len(data))
+
 		return http2StreamError{id, http2ErrCodeStreamClosed}
 	}
 	if st.body == nil {
 		panic("internal error: should have a body in this state")
 	}
-	data := f.Data()
 
 	if st.declBodyBytes != -1 && st.bodyBytes+int64(len(data)) > st.declBodyBytes {
 		st.body.CloseWithError(fmt.Errorf("sender tried to send more than declared Content-Length of %d bytes", st.declBodyBytes))
@@ -4919,9 +4939,10 @@ func (t *http2Transport) initConnPool() {
 // ClientConn is the state of a single HTTP/2 client connection to an
 // HTTP/2 server.
 type http2ClientConn struct {
-	t        *http2Transport
-	tconn    net.Conn             // usually *tls.Conn, except specialized impls
-	tlsState *tls.ConnectionState // nil only for specialized impls
+	t         *http2Transport
+	tconn     net.Conn             // usually *tls.Conn, except specialized impls
+	tlsState  *tls.ConnectionState // nil only for specialized impls
+	singleUse bool                 // whether being used for a single http.Request
 
 	// readLoop goroutine fields:
 	readerDone chan struct{} // closed on error
@@ -5117,7 +5138,7 @@ func http2shouldRetryRequest(req *Request, err error) bool {
 	return err == http2errClientConnUnusable
 }
 
-func (t *http2Transport) dialClientConn(addr string) (*http2ClientConn, error) {
+func (t *http2Transport) dialClientConn(addr string, singleUse bool) (*http2ClientConn, error) {
 	host, _, err := net.SplitHostPort(addr)
 	if err != nil {
 		return nil, err
@@ -5126,7 +5147,7 @@ func (t *http2Transport) dialClientConn(addr string) (*http2ClientConn, error) {
 	if err != nil {
 		return nil, err
 	}
-	return t.NewClientConn(tconn)
+	return t.newClientConn(tconn, singleUse)
 }
 
 func (t *http2Transport) newTLSConfig(host string) *tls.Config {
@@ -5187,6 +5208,10 @@ func (t *http2Transport) expectContinueTimeout() time.Duration {
 }
 
 func (t *http2Transport) NewClientConn(c net.Conn) (*http2ClientConn, error) {
+	return t.newClientConn(c, false)
+}
+
+func (t *http2Transport) newClientConn(c net.Conn, singleUse bool) (*http2ClientConn, error) {
 	if http2VerboseLogs {
 		t.vlogf("http2: Transport creating client conn to %v", c.RemoteAddr())
 	}
@@ -5204,6 +5229,7 @@ func (t *http2Transport) NewClientConn(c net.Conn) (*http2ClientConn, error) {
 		initialWindowSize:    65535,
 		maxConcurrentStreams: 1000,
 		streams:              make(map[uint32]*http2clientStream),
+		singleUse:            singleUse,
 	}
 	cc.cond = sync.NewCond(&cc.mu)
 	cc.flow.add(int32(http2initialWindowSize))
@@ -5288,6 +5314,9 @@ func (cc *http2ClientConn) CanTakeNewRequest() bool {
 }
 
 func (cc *http2ClientConn) canTakeNewRequestLocked() bool {
+	if cc.singleUse && cc.nextStreamID > 1 {
+		return false
+	}
 	return cc.goAway == nil && !cc.closed &&
 		int64(len(cc.streams)+1) < int64(cc.maxConcurrentStreams) &&
 		cc.nextStreamID < 2147483647
@@ -5494,22 +5523,26 @@ func (cc *http2ClientConn) RoundTrip(req *Request) (*Response, error) {
 	bodyWritten := false
 	ctx := http2reqContext(req)
 
+	handleReadLoopResponse := func(re http2resAndError) (*Response, error) {
+		res := re.res
+		if re.err != nil || res.StatusCode > 299 {
+
+			bodyWriter.cancel()
+			cs.abortRequestBodyWrite(http2errStopReqBodyWrite)
+		}
+		if re.err != nil {
+			cc.forgetStreamID(cs.ID)
+			return nil, re.err
+		}
+		res.Request = req
+		res.TLS = cc.tlsState
+		return res, nil
+	}
+
 	for {
 		select {
 		case re := <-readLoopResCh:
-			res := re.res
-			if re.err != nil || res.StatusCode > 299 {
-
-				bodyWriter.cancel()
-				cs.abortRequestBodyWrite(http2errStopReqBodyWrite)
-			}
-			if re.err != nil {
-				cc.forgetStreamID(cs.ID)
-				return nil, re.err
-			}
-			res.Request = req
-			res.TLS = cc.tlsState
-			return res, nil
+			return handleReadLoopResponse(re)
 		case <-respHeaderTimer:
 			cc.forgetStreamID(cs.ID)
 			if !hasBody || bodyWritten {
@@ -5541,6 +5574,12 @@ func (cc *http2ClientConn) RoundTrip(req *Request) (*Response, error) {
 
 			return nil, cs.resetErr
 		case err := <-bodyWriter.resc:
+
+			select {
+			case re := <-readLoopResCh:
+				return handleReadLoopResponse(re)
+			default:
+			}
 			if err != nil {
 				return nil, err
 			}
@@ -5932,7 +5971,7 @@ func (rl *http2clientConnReadLoop) cleanup() {
 
 func (rl *http2clientConnReadLoop) run() error {
 	cc := rl.cc
-	rl.closeWhenIdle = cc.t.disableKeepAlives()
+	rl.closeWhenIdle = cc.t.disableKeepAlives() || cc.singleUse
 	gotReply := false
 	for {
 		f, err := cc.fr.ReadFrame()
@@ -6216,10 +6255,27 @@ var http2errClosedResponseBody = errors.New("http2: response body closed")
 
 func (b http2transportResponseBody) Close() error {
 	cs := b.cs
-	if cs.bufPipe.Err() != io.EOF {
+	cc := cs.cc
 
-		cs.cc.writeStreamReset(cs.ID, http2ErrCodeCancel, nil)
+	serverSentStreamEnd := cs.bufPipe.Err() == io.EOF
+	unread := cs.bufPipe.Len()
+
+	if unread > 0 || !serverSentStreamEnd {
+		cc.mu.Lock()
+		cc.wmu.Lock()
+		if !serverSentStreamEnd {
+			cc.fr.WriteRSTStream(cs.ID, http2ErrCodeCancel)
+		}
+
+		if unread > 0 {
+			cc.inflow.add(int32(unread))
+			cc.fr.WriteWindowUpdate(0, uint32(unread))
+		}
+		cc.bw.Flush()
+		cc.wmu.Unlock()
+		cc.mu.Unlock()
 	}
+
 	cs.bufPipe.BreakWithError(http2errClosedResponseBody)
 	return nil
 }
@@ -6227,6 +6283,7 @@ func (b http2transportResponseBody) Close() error {
 func (rl *http2clientConnReadLoop) processData(f *http2DataFrame) error {
 	cc := rl.cc
 	cs := cc.streamByID(f.StreamID, f.StreamEnded())
+	data := f.Data()
 	if cs == nil {
 		cc.mu.Lock()
 		neverSent := cc.nextStreamID
@@ -6237,9 +6294,15 @@ func (rl *http2clientConnReadLoop) processData(f *http2DataFrame) error {
 			return http2ConnectionError(http2ErrCodeProtocol)
 		}
 
+		if len(data) > 0 {
+			cc.wmu.Lock()
+			cc.fr.WriteWindowUpdate(0, uint32(len(data)))
+			cc.bw.Flush()
+			cc.wmu.Unlock()
+		}
 		return nil
 	}
-	if data := f.Data(); len(data) > 0 {
+	if len(data) > 0 {
 		if cs.bufPipe.b == nil {
 
 			cc.logf("http2: Transport received DATA frame for closed stream; closing connection")
@@ -6282,7 +6345,7 @@ func (rl *http2clientConnReadLoop) endStreamError(cs *http2clientStream, err err
 	}
 	cs.bufPipe.closeWithErrorAndCode(err, code)
 	delete(rl.activeRes, cs.ID)
-	if cs.req.Close || cs.req.Header.Get("Connection") == "close" {
+	if http2isConnectionCloseRequest(cs.req) {
 		rl.closeWhenIdle = true
 	}
 }
@@ -6538,6 +6601,12 @@ func (s http2bodyWriterState) scheduleBodyWrite() {
 	}
 }
 
+// isConnectionCloseRequest reports whether req should use its own
+// connection for a single request and then close the connection.
+func http2isConnectionCloseRequest(req *Request) bool {
+	return req.Close || httplex.HeaderValuesContainsToken(req.Header["Connection"], "close")
+}
+
 // writeFramer is implemented by any type that is used to write frames.
 type http2writeFramer interface {
 	writeFrame(http2writeContext) error

From 4a15508c663429652d32f5363c0964152b28dd74 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Tue, 26 Jul 2016 23:58:44 +0200
Subject: [PATCH 09/16] crypto/x509: detect OS X version for FetchPEMRoots at
 run time

https://golang.org/cl/25233 was detecting the OS X release at compile
time, not run time. Detect it at run time instead.

Fixes #16473 (again)

Change-Id: I6bec4996e57aa50c52599c165aa6f1fae7423fa7
Reviewed-on: https://go-review.googlesource.com/25281
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
---
 src/crypto/x509/root_cgo_darwin.go | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/crypto/x509/root_cgo_darwin.go b/src/crypto/x509/root_cgo_darwin.go
index 83f83d8c16..a4b33c7660 100644
--- a/src/crypto/x509/root_cgo_darwin.go
+++ b/src/crypto/x509/root_cgo_darwin.go
@@ -10,6 +10,9 @@ package x509
 #cgo CFLAGS: -mmacosx-version-min=10.6 -D__MAC_OS_X_VERSION_MAX_ALLOWED=1060
 #cgo LDFLAGS: -framework CoreFoundation -framework Security
 
+#include <errno.h>
+#include <sys/sysctl.h>
+
 #include <CoreFoundation/CoreFoundation.h>
 #include <Security/Security.h>
 
@@ -51,9 +54,20 @@ int FetchPEMRoots_MountainLion(CFDataRef *pemRoots) {
 	return 0;
 }
 
-#ifndef kCFCoreFoundationVersionNumber10_9
-#define kCFCoreFoundationVersionNumber10_9      855.11
-#endif
+// useOldCode reports whether the running machine is OS X 10.8 Mountain Lion
+// or older. We only support Mountain Lion and higher, but we'll at least try our
+// best on older machines and continue to use the old code path.
+//
+// See golang.org/issue/16473
+int useOldCode() {
+	char str[256];
+	size_t size = sizeof(str);
+	memset(str, 0, size);
+	sysctlbyname("kern.osrelease", str, &size, NULL, 0);
+	// OS X 10.8 is osrelease "12.*", 10.7 is 11.*, 10.6 is 10.*.
+	// We never supported things before that.
+	return memcmp(str, "12.", 3) == 0 || memcmp(str, "11.", 3) == 0 || memcmp(str, "10.", 3) == 0;
+}
 
 // FetchPEMRoots fetches the system's list of trusted X.509 root certificates.
 //
@@ -63,7 +77,7 @@ int FetchPEMRoots_MountainLion(CFDataRef *pemRoots) {
 // Note: The CFDataRef returned in pemRoots must be released (using CFRelease) after
 // we've consumed its content.
 int FetchPEMRoots(CFDataRef *pemRoots) {
-	if (kCFCoreFoundationVersionNumber < kCFCoreFoundationVersionNumber10_9) {
+	if (useOldCode()) {
 		return FetchPEMRoots_MountainLion(pemRoots);
 	}
 

From c80e0d374ba3caf8ee32c6fe4a5474fa33928086 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Tue, 26 Jul 2016 23:44:00 +0200
Subject: [PATCH 10/16] net/http: fix data race with concurrent use of
 Server.Serve

Fixes #16505

Change-Id: I0afabcc8b1be3a5dbee59946b0c44d4c00a28d71
Reviewed-on: https://go-review.googlesource.com/25280
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
---
 src/net/http/serve_test.go | 11 +++++++++++
 src/net/http/server.go     | 38 +++++++++++++++++++++++++++++---------
 2 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/src/net/http/serve_test.go b/src/net/http/serve_test.go
index 139ce3eafc..13e5f283e4 100644
--- a/src/net/http/serve_test.go
+++ b/src/net/http/serve_test.go
@@ -4716,3 +4716,14 @@ func BenchmarkCloseNotifier(b *testing.B) {
 	}
 	b.StopTimer()
 }
+
+// Verify this doesn't race (Issue 16505)
+func TestConcurrentServerServe(t *testing.T) {
+	for i := 0; i < 100; i++ {
+		ln1 := &oneConnListener{conn: nil}
+		ln2 := &oneConnListener{conn: nil}
+		srv := Server{}
+		go func() { srv.Serve(ln1) }()
+		go func() { srv.Serve(ln2) }()
+	}
+}
diff --git a/src/net/http/server.go b/src/net/http/server.go
index 7b2b4b2f42..89574a8b36 100644
--- a/src/net/http/server.go
+++ b/src/net/http/server.go
@@ -2129,8 +2129,8 @@ type Server struct {
 	ErrorLog *log.Logger
 
 	disableKeepAlives int32     // accessed atomically.
-	nextProtoOnce     sync.Once // guards initialization of TLSNextProto in Serve
-	nextProtoErr      error
+	nextProtoOnce     sync.Once // guards setupHTTP2_* init
+	nextProtoErr      error     // result of http2.ConfigureServer if used
 }
 
 // A ConnState represents the state of a client connection to a server.
@@ -2260,10 +2260,8 @@ func (srv *Server) Serve(l net.Listener) error {
 	}
 	var tempDelay time.Duration // how long to sleep on accept failure
 
-	if srv.shouldConfigureHTTP2ForServe() {
-		if err := srv.setupHTTP2(); err != nil {
-			return err
-		}
+	if err := srv.setupHTTP2_Serve(); err != nil {
+		return err
 	}
 
 	// TODO: allow changing base context? can't imagine concrete
@@ -2408,7 +2406,7 @@ func (srv *Server) ListenAndServeTLS(certFile, keyFile string) error {
 
 	// Setup HTTP/2 before srv.Serve, to initialize srv.TLSConfig
 	// before we clone it and create the TLS Listener.
-	if err := srv.setupHTTP2(); err != nil {
+	if err := srv.setupHTTP2_ListenAndServeTLS(); err != nil {
 		return err
 	}
 
@@ -2436,14 +2434,36 @@ func (srv *Server) ListenAndServeTLS(certFile, keyFile string) error {
 	return srv.Serve(tlsListener)
 }
 
-func (srv *Server) setupHTTP2() error {
+// setupHTTP2_ListenAndServeTLS conditionally configures HTTP/2 on
+// srv and returns whether there was an error setting it up. If it is
+// not configured for policy reasons, nil is returned.
+func (srv *Server) setupHTTP2_ListenAndServeTLS() error {
 	srv.nextProtoOnce.Do(srv.onceSetNextProtoDefaults)
 	return srv.nextProtoErr
 }
 
+// setupHTTP2_Serve is called from (*Server).Serve and conditionally
+// configures HTTP/2 on srv using a more conservative policy than
+// setupHTTP2_ListenAndServeTLS because Serve may be called
+// concurrently.
+//
+// The tests named TestTransportAutomaticHTTP2* and
+// TestConcurrentServerServe in server_test.go demonstrate some
+// of the supported use cases and motivations.
+func (srv *Server) setupHTTP2_Serve() error {
+	srv.nextProtoOnce.Do(srv.onceSetNextProtoDefaults_Serve)
+	return srv.nextProtoErr
+}
+
+func (srv *Server) onceSetNextProtoDefaults_Serve() {
+	if srv.shouldConfigureHTTP2ForServe() {
+		srv.onceSetNextProtoDefaults()
+	}
+}
+
 // onceSetNextProtoDefaults configures HTTP/2, if the user hasn't
 // configured otherwise. (by setting srv.TLSNextProto non-nil)
-// It must only be called via srv.nextProtoOnce (use srv.setupHTTP2).
+// It must only be called via srv.nextProtoOnce (use srv.setupHTTP2_*).
 func (srv *Server) onceSetNextProtoDefaults() {
 	if strings.Contains(os.Getenv("GODEBUG"), "http2server=0") {
 		return

From ccca9c9cc0fa5b6ea6e5c8276a96eee8c27ebd87 Mon Sep 17 00:00:00 2001
From: Rhys Hiltner <rhys@justin.tv>
Date: Fri, 22 Jul 2016 16:36:30 -0700
Subject: [PATCH 11/16] runtime: reduce GC assist extra credit

Mutator goroutines that allocate memory during the concurrent mark
phase are required to spend some time assisting the garbage
collector. The magnitude of this mandatory assistance is proportional
to the goroutine's allocation debt and subject to the assistance
ratio as calculated by the pacer.

When assisting the garbage collector, a mutator goroutine will go
beyond paying off its allocation debt. It will build up extra credit
to amortize the overhead of the assist.

In fast-allocating applications with high assist ratios, building up
this credit can take the affected goroutine's entire time slice.
Reduce the penalty on each goroutine being selected to assist the GC
in two ways, to spread the responsibility more evenly.

First, do a consistent amount of extra scan work without regard for
the pacer's assistance ratio. Second, reduce the magnitude of the
extra scan work so it can be completed within a few hundred
microseconds.

Commentary on gcOverAssistWork is by Austin Clements, originally in
https://golang.org/cl/24704

Updates #14812
Fixes #16432

Change-Id: I436f899e778c20daa314f3e9f0e2a1bbd53b43e1
Reviewed-on: https://go-review.googlesource.com/25155
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
---
 src/runtime/mgc.go     |  9 ++++-----
 src/runtime/mgcmark.go | 11 ++++++++---
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index 1eabf43d6f..3b238cba1c 100644
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -741,11 +741,10 @@ const gcCreditSlack = 2000
 // can accumulate on a P before updating gcController.assistTime.
 const gcAssistTimeSlack = 5000
 
-// gcOverAssistBytes determines how many extra allocation bytes of
-// assist credit a GC assist builds up when an assist happens. This
-// amortizes the cost of an assist by pre-paying for this many bytes
-// of future allocations.
-const gcOverAssistBytes = 1 << 20
+// gcOverAssistWork determines how many extra units of scan work a GC
+// assist does when an assist happens. This amortizes the cost of an
+// assist by pre-paying for this many bytes of future allocations.
+const gcOverAssistWork = 64 << 10
 
 var work struct {
 	full  uint64                   // lock-free list of full blocks workbuf
diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index 00b96fd00b..aa7f7a7769 100644
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -393,10 +393,15 @@ func gcAssistAlloc(gp *g) {
 	}
 
 	// Compute the amount of scan work we need to do to make the
-	// balance positive. We over-assist to build up credit for
-	// future allocations and amortize the cost of assisting.
-	debtBytes := -gp.gcAssistBytes + gcOverAssistBytes
+	// balance positive. When the required amount of work is low,
+	// we over-assist to build up credit for future allocations
+	// and amortize the cost of assisting.
+	debtBytes := -gp.gcAssistBytes
 	scanWork := int64(gcController.assistWorkPerByte * float64(debtBytes))
+	if scanWork < gcOverAssistWork {
+		scanWork = gcOverAssistWork
+		debtBytes = int64(gcController.assistBytesPerWork * float64(scanWork))
+	}
 
 retry:
 	// Steal as much credit as we can from the background GC's

From be915159073ed93fa511ceef7256bc8ee396d1c7 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Wed, 27 Jul 2016 08:51:47 +0200
Subject: [PATCH 12/16] doc/go1.7.html: add known issues section for FreeBSD
 crashes

Updates #16396

Change-Id: I7b4f85610e66f2c77c17cf8898cc41d81b2efc8c
Reviewed-on: https://go-review.googlesource.com/25283
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
---
 doc/go1.7.html | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/doc/go1.7.html b/doc/go1.7.html
index cf5d8a48a5..409f7ab943 100644
--- a/doc/go1.7.html
+++ b/doc/go1.7.html
@@ -102,6 +102,17 @@ POWER5 architecture.
 The OpenBSD port now requires OpenBSD 5.6 or later, for access to the <a href="http://man.openbsd.org/getentropy.2"><i>getentropy</i>(2)</a> system call.
 </p>
 
+<h3 id="known_issues">Known Issues</h3>
+
+<p>
+There are some instabilities on FreeBSD that are known but not understood.
+These can lead to program crashes in rare cases.
+See <a href="https://golang.org/issue/16136">issue 16136</a>,
+<a href="https://golang.org/issue/15658">issue 15658</a>,
+and <a href="https://golang.org/issue/16396">issue 16396</a>.
+Any help in solving these FreeBSD-specific issues would be appreciated.
+</p>
+
 <h2 id="tools">Tools</h2>
 
 <h3 id="cmd_asm">Assembler</h3>

From 111d590f86e2c9a55ec08d95fc4e9adea9232f0c Mon Sep 17 00:00:00 2001
From: Cherry Zhang <cherryyz@google.com>
Date: Thu, 28 Jul 2016 12:22:49 -0400
Subject: [PATCH 13/16] cmd/compile: fix possible spill of invalid pointer with
 DUFFZERO on AMD64

SSA compiler on AMD64 may spill Duff-adjusted address as scalar. If
the object is on stack and the stack moves, the spilled address become
invalid.

Making the spill pointer-typed does not work. The Duff-adjusted address
points to the memory before the area to be zeroed and may be invalid.
This may cause stack scanning code panic.

Fix it by doing Duff-adjustment in genValue, so the intermediate value
is not seen by the reg allocator, and will not be spilled.

Add a test to cover both cases. As it depends on allocation, it may
be not always triggered.

Fixes #16515.

Change-Id: Ia81d60204782de7405b7046165ad063384ede0db
Reviewed-on: https://go-review.googlesource.com/25309
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
---
 src/cmd/compile/internal/amd64/ssa.go        | 44 +++++++++++++++-
 src/cmd/compile/internal/ssa/gen/AMD64.rules |  2 +-
 src/cmd/compile/internal/ssa/gen/AMD64Ops.go |  4 +-
 src/cmd/compile/internal/ssa/rewrite.go      | 46 -----------------
 src/cmd/compile/internal/ssa/rewriteAMD64.go | 13 ++---
 test/fixedbugs/issue16515.go                 | 53 ++++++++++++++++++++
 6 files changed, 103 insertions(+), 59 deletions(-)
 create mode 100644 test/fixedbugs/issue16515.go

diff --git a/src/cmd/compile/internal/amd64/ssa.go b/src/cmd/compile/internal/amd64/ssa.go
index 756bcec75c..0350c295ec 100644
--- a/src/cmd/compile/internal/amd64/ssa.go
+++ b/src/cmd/compile/internal/amd64/ssa.go
@@ -156,6 +156,36 @@ func opregreg(op obj.As, dest, src int16) *obj.Prog {
 	return p
 }
 
+// DUFFZERO consists of repeated blocks of 4 MOVUPSs + ADD,
+// See runtime/mkduff.go.
+func duffStart(size int64) int64 {
+	x, _ := duff(size)
+	return x
+}
+func duffAdj(size int64) int64 {
+	_, x := duff(size)
+	return x
+}
+
+// duff returns the offset (from duffzero, in bytes) and pointer adjust (in bytes)
+// required to use the duffzero mechanism for a block of the given size.
+func duff(size int64) (int64, int64) {
+	if size < 32 || size > 1024 || size%dzClearStep != 0 {
+		panic("bad duffzero size")
+	}
+	steps := size / dzClearStep
+	blocks := steps / dzBlockLen
+	steps %= dzBlockLen
+	off := dzBlockSize * (dzBlocks - blocks)
+	var adj int64
+	if steps != 0 {
+		off -= dzAddSize
+		off -= dzMovSize * steps
+		adj -= dzClearStep * (dzBlockLen - steps)
+	}
+	return off, adj
+}
+
 func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	s.SetLineno(v.Line)
 	switch v.Op {
@@ -649,10 +679,20 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		ssa.OpAMD64CVTSS2SD, ssa.OpAMD64CVTSD2SS:
 		opregreg(v.Op.Asm(), gc.SSARegNum(v), gc.SSARegNum(v.Args[0]))
 	case ssa.OpAMD64DUFFZERO:
-		p := gc.Prog(obj.ADUFFZERO)
+		off := duffStart(v.AuxInt)
+		adj := duffAdj(v.AuxInt)
+		var p *obj.Prog
+		if adj != 0 {
+			p = gc.Prog(x86.AADDQ)
+			p.From.Type = obj.TYPE_CONST
+			p.From.Offset = adj
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = x86.REG_DI
+		}
+		p = gc.Prog(obj.ADUFFZERO)
 		p.To.Type = obj.TYPE_ADDR
 		p.To.Sym = gc.Linksym(gc.Pkglookup("duffzero", gc.Runtimepkg))
-		p.To.Offset = v.AuxInt
+		p.To.Offset = off
 	case ssa.OpAMD64MOVOconst:
 		if v.AuxInt != 0 {
 			v.Unimplementedf("MOVOconst can only do constant=0")
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules
index db274d7eb9..d27eff0f6a 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules
@@ -389,7 +389,7 @@
 (Zero [size] destptr mem) && size <= 1024 && size%8 == 0 && size%16 != 0 && !config.noDuffDevice ->
 	(Zero [size-8] (ADDQconst [8] destptr) (MOVQstore destptr (MOVQconst [0]) mem))
 (Zero [size] destptr mem) && size <= 1024 && size%16 == 0 && !config.noDuffDevice ->
-	(DUFFZERO [duffStart(size)] (ADDQconst [duffAdj(size)] destptr) (MOVOconst [0]) mem)
+	(DUFFZERO [size] destptr (MOVOconst [0]) mem)
 
 // Large zeroing uses REP STOSQ.
 (Zero [size] destptr mem) && (size > 1024 || (config.noDuffDevice && size > 32)) && size%8 == 0 ->
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64Ops.go b/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
index b684b9ccdf..43cc0eb5b3 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
@@ -425,10 +425,10 @@ func init() {
 		{name: "MOVQstoreconstidx1", argLength: 3, reg: gpstoreconstidx, asm: "MOVQ", aux: "SymValAndOff", typ: "Mem"}, // store 8 bytes of ... arg1 ...
 		{name: "MOVQstoreconstidx8", argLength: 3, reg: gpstoreconstidx, asm: "MOVQ", aux: "SymValAndOff", typ: "Mem"}, // store 8 bytes of ... 8*arg1 ...
 
-		// arg0 = (duff-adjusted) pointer to start of memory to zero
+		// arg0 = pointer to start of memory to zero
 		// arg1 = value to store (will always be zero)
 		// arg2 = mem
-		// auxint = offset into duffzero code to start executing
+		// auxint = # of bytes to zero
 		// returns mem
 		{
 			name:      "DUFFZERO",
diff --git a/src/cmd/compile/internal/ssa/rewrite.go b/src/cmd/compile/internal/ssa/rewrite.go
index 03c38827cc..61d4234c65 100644
--- a/src/cmd/compile/internal/ssa/rewrite.go
+++ b/src/cmd/compile/internal/ssa/rewrite.go
@@ -254,52 +254,6 @@ func isSamePtr(p1, p2 *Value) bool {
 	return false
 }
 
-// DUFFZERO consists of repeated blocks of 4 MOVUPSs + ADD,
-// See runtime/mkduff.go.
-const (
-	dzBlocks    = 16 // number of MOV/ADD blocks
-	dzBlockLen  = 4  // number of clears per block
-	dzBlockSize = 19 // size of instructions in a single block
-	dzMovSize   = 4  // size of single MOV instruction w/ offset
-	dzAddSize   = 4  // size of single ADD instruction
-	dzClearStep = 16 // number of bytes cleared by each MOV instruction
-
-	dzTailLen  = 4 // number of final STOSQ instructions
-	dzTailSize = 2 // size of single STOSQ instruction
-
-	dzClearLen = dzClearStep * dzBlockLen // bytes cleared by one block
-	dzSize     = dzBlocks * dzBlockSize
-)
-
-func duffStart(size int64) int64 {
-	x, _ := duff(size)
-	return x
-}
-func duffAdj(size int64) int64 {
-	_, x := duff(size)
-	return x
-}
-
-// duff returns the offset (from duffzero, in bytes) and pointer adjust (in bytes)
-// required to use the duffzero mechanism for a block of the given size.
-func duff(size int64) (int64, int64) {
-	if size < 32 || size > 1024 || size%dzClearStep != 0 {
-		panic("bad duffzero size")
-	}
-	// TODO: arch-dependent
-	steps := size / dzClearStep
-	blocks := steps / dzBlockLen
-	steps %= dzBlockLen
-	off := dzBlockSize * (dzBlocks - blocks)
-	var adj int64
-	if steps != 0 {
-		off -= dzAddSize
-		off -= dzMovSize * steps
-		adj -= dzClearStep * (dzBlockLen - steps)
-	}
-	return off, adj
-}
-
 // mergePoint finds a block among a's blocks which dominates b and is itself
 // dominated by all of a's blocks. Returns nil if it can't find one.
 // Might return nil even if one does exist.
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index cefd50ca56..a2b9e15a4f 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -17175,7 +17175,7 @@ func rewriteValueAMD64_OpZero(v *Value, config *Config) bool {
 	}
 	// match: (Zero [size] destptr mem)
 	// cond: size <= 1024 && size%16 == 0 && !config.noDuffDevice
-	// result: (DUFFZERO [duffStart(size)] (ADDQconst [duffAdj(size)] destptr) (MOVOconst [0]) mem)
+	// result: (DUFFZERO [size] destptr (MOVOconst [0]) mem)
 	for {
 		size := v.AuxInt
 		destptr := v.Args[0]
@@ -17184,14 +17184,11 @@ func rewriteValueAMD64_OpZero(v *Value, config *Config) bool {
 			break
 		}
 		v.reset(OpAMD64DUFFZERO)
-		v.AuxInt = duffStart(size)
-		v0 := b.NewValue0(v.Line, OpAMD64ADDQconst, config.fe.TypeUInt64())
-		v0.AuxInt = duffAdj(size)
-		v0.AddArg(destptr)
+		v.AuxInt = size
+		v.AddArg(destptr)
+		v0 := b.NewValue0(v.Line, OpAMD64MOVOconst, TypeInt128)
+		v0.AuxInt = 0
 		v.AddArg(v0)
-		v1 := b.NewValue0(v.Line, OpAMD64MOVOconst, TypeInt128)
-		v1.AuxInt = 0
-		v.AddArg(v1)
 		v.AddArg(mem)
 		return true
 	}
diff --git a/test/fixedbugs/issue16515.go b/test/fixedbugs/issue16515.go
new file mode 100644
index 0000000000..6b67436383
--- /dev/null
+++ b/test/fixedbugs/issue16515.go
@@ -0,0 +1,53 @@
+// run
+
+// Copyright 2016 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// issue 16515: spilled Duff-adjusted address may be invalid
+
+package main
+
+import "runtime"
+
+type T [62]int // DUFFZERO with non-zero adjustment on AMD64
+
+var sink interface{}
+
+//go:noinline
+func zero(x *T) {
+	// Two DUFFZEROs on the same address with a function call in between.
+	// Duff-adjusted address will be spilled and loaded
+
+	*x = T{} // DUFFZERO
+	runtime.GC()
+	(*x)[0] = 1
+	g()      // call a function with large frame, trigger a stack move
+	*x = T{} // DUFFZERO again
+}
+
+//go:noinline
+// a function with large frame
+func g() {
+	var x [1000]int
+	_ = x
+}
+
+func main() {
+	var s struct { a T; b [8192-62]int } // allocate 64K, hopefully it's in a new span and a few bytes before it is garbage
+	sink = &s // force heap allocation
+	s.a[0] = 2
+	zero(&s.a)
+	if s.a[0] != 0 {
+		println("s.a[0] =", s.a[0])
+		panic("zeroing failed")
+	}
+
+	var a T // on stack
+	a[0] = 2
+	zero(&a)
+	if a[0] != 0 {
+		println("a[0] =", a[0])
+		panic("zeroing failed")
+	}
+}

From c558a539b5efaeda4b6f8e61f51c21f64d1b94f6 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Mon, 1 Aug 2016 23:44:22 +0000
Subject: [PATCH 14/16] net/http: update bundled http2

Updates bundled http2 to x/net/http2 rev 28d1bd4f for:

    http2: make Transport work around mod_h2 bug
    https://golang.org/cl/25362

    http2: don't ignore DATA padding in flow control
    https://golang.org/cl/25382

Updates #16519
Updates #16556
Updates #16481

Change-Id: I51f5696e977c91bdb2d80d2d56b8a78e3222da3f
Reviewed-on: https://go-review.googlesource.com/25388
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---
 src/net/http/h2_bundle.go | 232 +++++++++++++++++++++++---------------
 1 file changed, 142 insertions(+), 90 deletions(-)

diff --git a/src/net/http/h2_bundle.go b/src/net/http/h2_bundle.go
index a117897bcf..cd66c0960e 100644
--- a/src/net/http/h2_bundle.go
+++ b/src/net/http/h2_bundle.go
@@ -1115,6 +1115,7 @@ func http2parseDataFrame(fh http2FrameHeader, payload []byte) (http2Frame, error
 var (
 	http2errStreamID    = errors.New("invalid stream ID")
 	http2errDepStreamID = errors.New("invalid dependent stream ID")
+	http2errPadLength   = errors.New("pad length too large")
 )
 
 func http2validStreamIDOrZero(streamID uint32) bool {
@@ -1128,18 +1129,40 @@ func http2validStreamID(streamID uint32) bool {
 // WriteData writes a DATA frame.
 //
 // It will perform exactly one Write to the underlying Writer.
-// It is the caller's responsibility to not call other Write methods concurrently.
+// It is the caller's responsibility not to violate the maximum frame size
+// and to not call other Write methods concurrently.
 func (f *http2Framer) WriteData(streamID uint32, endStream bool, data []byte) error {
+	return f.WriteDataPadded(streamID, endStream, data, nil)
+}
 
+// WriteData writes a DATA frame with optional padding.
+//
+// If pad is nil, the padding bit is not sent.
+// The length of pad must not exceed 255 bytes.
+//
+// It will perform exactly one Write to the underlying Writer.
+// It is the caller's responsibility not to violate the maximum frame size
+// and to not call other Write methods concurrently.
+func (f *http2Framer) WriteDataPadded(streamID uint32, endStream bool, data, pad []byte) error {
 	if !http2validStreamID(streamID) && !f.AllowIllegalWrites {
 		return http2errStreamID
 	}
+	if len(pad) > 255 {
+		return http2errPadLength
+	}
 	var flags http2Flags
 	if endStream {
 		flags |= http2FlagDataEndStream
 	}
+	if pad != nil {
+		flags |= http2FlagDataPadded
+	}
 	f.startWrite(http2FrameData, flags, streamID)
+	if pad != nil {
+		f.wbuf = append(f.wbuf, byte(len(pad)))
+	}
 	f.wbuf = append(f.wbuf, data...)
+	f.wbuf = append(f.wbuf, pad...)
 	return f.endWrite()
 }
 
@@ -3898,12 +3921,12 @@ func (sc *http2serverConn) processData(f *http2DataFrame) error {
 	st, ok := sc.streams[id]
 	if !ok || st.state != http2stateOpen || st.gotTrailerHeader {
 
-		if int(sc.inflow.available()) < len(data) {
+		if sc.inflow.available() < int32(f.Length) {
 			return http2StreamError{id, http2ErrCodeFlowControl}
 		}
 
-		sc.inflow.take(int32(len(data)))
-		sc.sendWindowUpdate(nil, len(data))
+		sc.inflow.take(int32(f.Length))
+		sc.sendWindowUpdate(nil, int(f.Length))
 
 		return http2StreamError{id, http2ErrCodeStreamClosed}
 	}
@@ -3915,20 +3938,28 @@ func (sc *http2serverConn) processData(f *http2DataFrame) error {
 		st.body.CloseWithError(fmt.Errorf("sender tried to send more than declared Content-Length of %d bytes", st.declBodyBytes))
 		return http2StreamError{id, http2ErrCodeStreamClosed}
 	}
-	if len(data) > 0 {
+	if f.Length > 0 {
 
-		if int(st.inflow.available()) < len(data) {
+		if st.inflow.available() < int32(f.Length) {
 			return http2StreamError{id, http2ErrCodeFlowControl}
 		}
-		st.inflow.take(int32(len(data)))
-		wrote, err := st.body.Write(data)
-		if err != nil {
-			return http2StreamError{id, http2ErrCodeStreamClosed}
+		st.inflow.take(int32(f.Length))
+
+		if len(data) > 0 {
+			wrote, err := st.body.Write(data)
+			if err != nil {
+				return http2StreamError{id, http2ErrCodeStreamClosed}
+			}
+			if wrote != len(data) {
+				panic("internal error: bad Writer")
+			}
+			st.bodyBytes += int64(len(data))
 		}
-		if wrote != len(data) {
-			panic("internal error: bad Writer")
+
+		if pad := int32(f.Length) - int32(len(data)); pad > 0 {
+			sc.sendWindowUpdate32(nil, pad)
+			sc.sendWindowUpdate32(st, pad)
 		}
-		st.bodyBytes += int64(len(data))
 	}
 	if f.StreamEnded() {
 		st.endStream()
@@ -4948,19 +4979,20 @@ type http2ClientConn struct {
 	readerDone chan struct{} // closed on error
 	readerErr  error         // set before readerDone is closed
 
-	mu           sync.Mutex // guards following
-	cond         *sync.Cond // hold mu; broadcast on flow/closed changes
-	flow         http2flow  // our conn-level flow control quota (cs.flow is per stream)
-	inflow       http2flow  // peer's conn-level flow control
-	closed       bool
-	goAway       *http2GoAwayFrame             // if non-nil, the GoAwayFrame we received
-	goAwayDebug  string                        // goAway frame's debug data, retained as a string
-	streams      map[uint32]*http2clientStream // client-initiated
-	nextStreamID uint32
-	bw           *bufio.Writer
-	br           *bufio.Reader
-	fr           *http2Framer
-	lastActive   time.Time
+	mu              sync.Mutex // guards following
+	cond            *sync.Cond // hold mu; broadcast on flow/closed changes
+	flow            http2flow  // our conn-level flow control quota (cs.flow is per stream)
+	inflow          http2flow  // peer's conn-level flow control
+	closed          bool
+	wantSettingsAck bool                          // we sent a SETTINGS frame and haven't heard back
+	goAway          *http2GoAwayFrame             // if non-nil, the GoAwayFrame we received
+	goAwayDebug     string                        // goAway frame's debug data, retained as a string
+	streams         map[uint32]*http2clientStream // client-initiated
+	nextStreamID    uint32
+	bw              *bufio.Writer
+	br              *bufio.Reader
+	fr              *http2Framer
+	lastActive      time.Time
 
 	// Settings from peer:
 	maxFrameSize         uint32
@@ -5215,10 +5247,6 @@ func (t *http2Transport) newClientConn(c net.Conn, singleUse bool) (*http2Client
 	if http2VerboseLogs {
 		t.vlogf("http2: Transport creating client conn to %v", c.RemoteAddr())
 	}
-	if _, err := c.Write(http2clientPreface); err != nil {
-		t.vlogf("client preface write error: %v", err)
-		return nil, err
-	}
 
 	cc := &http2ClientConn{
 		t:                    t,
@@ -5230,6 +5258,7 @@ func (t *http2Transport) newClientConn(c net.Conn, singleUse bool) (*http2Client
 		maxConcurrentStreams: 1000,
 		streams:              make(map[uint32]*http2clientStream),
 		singleUse:            singleUse,
+		wantSettingsAck:      true,
 	}
 	cc.cond = sync.NewCond(&cc.mu)
 	cc.flow.add(int32(http2initialWindowSize))
@@ -5254,6 +5283,8 @@ func (t *http2Transport) newClientConn(c net.Conn, singleUse bool) (*http2Client
 	if max := t.maxHeaderListSize(); max != 0 {
 		initialSettings = append(initialSettings, http2Setting{ID: http2SettingMaxHeaderListSize, Val: max})
 	}
+
+	cc.bw.Write(http2clientPreface)
 	cc.fr.WriteSettings(initialSettings...)
 	cc.fr.WriteWindowUpdate(0, http2transportDefaultConnFlow)
 	cc.inflow.add(http2transportDefaultConnFlow + http2initialWindowSize)
@@ -5262,32 +5293,6 @@ func (t *http2Transport) newClientConn(c net.Conn, singleUse bool) (*http2Client
 		return nil, cc.werr
 	}
 
-	f, err := cc.fr.ReadFrame()
-	if err != nil {
-		return nil, err
-	}
-	sf, ok := f.(*http2SettingsFrame)
-	if !ok {
-		return nil, fmt.Errorf("expected settings frame, got: %T", f)
-	}
-	cc.fr.WriteSettingsAck()
-	cc.bw.Flush()
-
-	sf.ForeachSetting(func(s http2Setting) error {
-		switch s.ID {
-		case http2SettingMaxFrameSize:
-			cc.maxFrameSize = s.Val
-		case http2SettingMaxConcurrentStreams:
-			cc.maxConcurrentStreams = s.Val
-		case http2SettingInitialWindowSize:
-			cc.initialWindowSize = s.Val
-		default:
-
-			t.vlogf("Unhandled Setting: %v", s)
-		}
-		return nil
-	})
-
 	go cc.readLoop()
 	return cc, nil
 }
@@ -5687,26 +5692,24 @@ func (cs *http2clientStream) writeRequestBody(body io.Reader, bodyCloser io.Clos
 		}
 	}
 
-	cc.wmu.Lock()
-	if !sentEnd {
-		var trls []byte
-		if hasTrailers {
-			cc.mu.Lock()
-			trls = cc.encodeTrailers(req)
-			cc.mu.Unlock()
-		}
+	var trls []byte
+	if !sentEnd && hasTrailers {
+		cc.mu.Lock()
+		defer cc.mu.Unlock()
+		trls = cc.encodeTrailers(req)
+	}
 
-		if len(trls) > 0 {
-			err = cc.writeHeaders(cs.ID, true, trls)
-		} else {
-			err = cc.fr.WriteData(cs.ID, true, nil)
-		}
+	cc.wmu.Lock()
+	defer cc.wmu.Unlock()
+
+	if len(trls) > 0 {
+		err = cc.writeHeaders(cs.ID, true, trls)
+	} else {
+		err = cc.fr.WriteData(cs.ID, true, nil)
 	}
 	if ferr := cc.bw.Flush(); ferr != nil && err == nil {
 		err = ferr
 	}
-	cc.wmu.Unlock()
-
 	return err
 }
 
@@ -5935,6 +5938,14 @@ func (e http2GoAwayError) Error() string {
 		e.LastStreamID, e.ErrCode, e.DebugData)
 }
 
+func http2isEOFOrNetReadError(err error) bool {
+	if err == io.EOF {
+		return true
+	}
+	ne, ok := err.(*net.OpError)
+	return ok && ne.Op == "read"
+}
+
 func (rl *http2clientConnReadLoop) cleanup() {
 	cc := rl.cc
 	defer cc.tconn.Close()
@@ -5943,16 +5954,14 @@ func (rl *http2clientConnReadLoop) cleanup() {
 
 	err := cc.readerErr
 	cc.mu.Lock()
-	if err == io.EOF {
-		if cc.goAway != nil {
-			err = http2GoAwayError{
-				LastStreamID: cc.goAway.LastStreamID,
-				ErrCode:      cc.goAway.ErrCode,
-				DebugData:    cc.goAwayDebug,
-			}
-		} else {
-			err = io.ErrUnexpectedEOF
+	if cc.goAway != nil && http2isEOFOrNetReadError(err) {
+		err = http2GoAwayError{
+			LastStreamID: cc.goAway.LastStreamID,
+			ErrCode:      cc.goAway.ErrCode,
+			DebugData:    cc.goAwayDebug,
 		}
+	} else if err == io.EOF {
+		err = io.ErrUnexpectedEOF
 	}
 	for _, cs := range rl.activeRes {
 		cs.bufPipe.CloseWithError(err)
@@ -5973,6 +5982,7 @@ func (rl *http2clientConnReadLoop) run() error {
 	cc := rl.cc
 	rl.closeWhenIdle = cc.t.disableKeepAlives() || cc.singleUse
 	gotReply := false
+	gotSettings := false
 	for {
 		f, err := cc.fr.ReadFrame()
 		if err != nil {
@@ -5989,6 +5999,13 @@ func (rl *http2clientConnReadLoop) run() error {
 		if http2VerboseLogs {
 			cc.vlogf("http2: Transport received %s", http2summarizeFrame(f))
 		}
+		if !gotSettings {
+			if _, ok := f.(*http2SettingsFrame); !ok {
+				cc.logf("protocol error: received %T before a SETTINGS frame", f)
+				return http2ConnectionError(http2ErrCodeProtocol)
+			}
+			gotSettings = true
+		}
 		maybeIdle := false
 
 		switch f := f.(type) {
@@ -6294,33 +6311,49 @@ func (rl *http2clientConnReadLoop) processData(f *http2DataFrame) error {
 			return http2ConnectionError(http2ErrCodeProtocol)
 		}
 
-		if len(data) > 0 {
+		if f.Length > 0 {
+			cc.mu.Lock()
+			cc.inflow.add(int32(f.Length))
+			cc.mu.Unlock()
+
 			cc.wmu.Lock()
-			cc.fr.WriteWindowUpdate(0, uint32(len(data)))
+			cc.fr.WriteWindowUpdate(0, uint32(f.Length))
 			cc.bw.Flush()
 			cc.wmu.Unlock()
 		}
 		return nil
 	}
-	if len(data) > 0 {
-		if cs.bufPipe.b == nil {
+	if f.Length > 0 {
+		if len(data) > 0 && cs.bufPipe.b == nil {
 
 			cc.logf("http2: Transport received DATA frame for closed stream; closing connection")
 			return http2ConnectionError(http2ErrCodeProtocol)
 		}
 
 		cc.mu.Lock()
-		if cs.inflow.available() >= int32(len(data)) {
-			cs.inflow.take(int32(len(data)))
+		if cs.inflow.available() >= int32(f.Length) {
+			cs.inflow.take(int32(f.Length))
 		} else {
 			cc.mu.Unlock()
 			return http2ConnectionError(http2ErrCodeFlowControl)
 		}
+
+		if pad := int32(f.Length) - int32(len(data)); pad > 0 {
+			cs.inflow.add(pad)
+			cc.inflow.add(pad)
+			cc.wmu.Lock()
+			cc.fr.WriteWindowUpdate(0, uint32(pad))
+			cc.fr.WriteWindowUpdate(cs.ID, uint32(pad))
+			cc.bw.Flush()
+			cc.wmu.Unlock()
+		}
 		cc.mu.Unlock()
 
-		if _, err := cs.bufPipe.Write(data); err != nil {
-			rl.endStreamError(cs, err)
-			return err
+		if len(data) > 0 {
+			if _, err := cs.bufPipe.Write(data); err != nil {
+				rl.endStreamError(cs, err)
+				return err
+			}
 		}
 	}
 
@@ -6375,7 +6408,16 @@ func (rl *http2clientConnReadLoop) processSettings(f *http2SettingsFrame) error
 	cc := rl.cc
 	cc.mu.Lock()
 	defer cc.mu.Unlock()
-	return f.ForeachSetting(func(s http2Setting) error {
+
+	if f.IsAck() {
+		if cc.wantSettingsAck {
+			cc.wantSettingsAck = false
+			return nil
+		}
+		return http2ConnectionError(http2ErrCodeProtocol)
+	}
+
+	err := f.ForeachSetting(func(s http2Setting) error {
 		switch s.ID {
 		case http2SettingMaxFrameSize:
 			cc.maxFrameSize = s.Val
@@ -6390,6 +6432,16 @@ func (rl *http2clientConnReadLoop) processSettings(f *http2SettingsFrame) error
 		}
 		return nil
 	})
+	if err != nil {
+		return err
+	}
+
+	cc.wmu.Lock()
+	defer cc.wmu.Unlock()
+
+	cc.fr.WriteSettingsAck()
+	cc.bw.Flush()
+	return cc.werr
 }
 
 func (rl *http2clientConnReadLoop) processWindowUpdate(f *http2WindowUpdateFrame) error {

From 2629446df0cb906986f377d45cde307ffdae9675 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Tue, 2 Aug 2016 00:41:12 +0000
Subject: [PATCH 15/16] doc/go1.7.html: mention Server.Serve HTTP/2 behavior
 change

Fixes #16550
Updates #15908

Change-Id: Ic951080dbc88f96e4c00cdb3ffe24a5c03079efd
Reviewed-on: https://go-review.googlesource.com/25389
Reviewed-by: Chris Broadfoot <cbro@golang.org>
---
 doc/go1.7.html | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/go1.7.html b/doc/go1.7.html
index 409f7ab943..7e17ff2424 100644
--- a/doc/go1.7.html
+++ b/doc/go1.7.html
@@ -916,6 +916,12 @@ For example, the address on which a request received is
 <code>req.Context().Value(http.LocalAddrContextKey).(net.Addr)</code>.
 </p>
 
+<p>
+The server's <a href="/pkg/net/http/#Server.Serve"><code>Serve</code></a> method
+now only enables HTTP/2 support if the <code>Server.TLSConfig</code> field is <code>nil</code>
+or includes <code>"h2"</code> in its <code>TLSConfig.NextProto</code>.
+</p>
+
 <p>
 The server implementation now
 pads response codes less than 100 to three digits

From 28ee17965703c4ef81cc97e5088539fe3e8e541f Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Thu, 28 Jul 2016 13:42:11 +0200
Subject: [PATCH 16/16] net: prevent cancelation goroutine from adjusting fd
 timeout after connect

This was previously fixed in https://golang.org/cl/21497 but not enough.

Fixes #16523

Change-Id: I678543a656304c82d654e25e12fb094cd6cc87e8
Reviewed-on: https://go-review.googlesource.com/25330
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---
 src/net/dial_unix_test.go | 108 ++++++++++++++++++++++++++++++++++++++
 src/net/fd_unix.go        |  55 +++++++++++++------
 src/net/hook_unix.go      |   3 +-
 3 files changed, 149 insertions(+), 17 deletions(-)
 create mode 100644 src/net/dial_unix_test.go

diff --git a/src/net/dial_unix_test.go b/src/net/dial_unix_test.go
new file mode 100644
index 0000000000..4705254728
--- /dev/null
+++ b/src/net/dial_unix_test.go
@@ -0,0 +1,108 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package net
+
+import (
+	"context"
+	"syscall"
+	"testing"
+	"time"
+)
+
+// Issue 16523
+func TestDialContextCancelRace(t *testing.T) {
+	oldConnectFunc := connectFunc
+	oldGetsockoptIntFunc := getsockoptIntFunc
+	oldTestHookCanceledDial := testHookCanceledDial
+	defer func() {
+		connectFunc = oldConnectFunc
+		getsockoptIntFunc = oldGetsockoptIntFunc
+		testHookCanceledDial = oldTestHookCanceledDial
+	}()
+
+	ln, err := newLocalListener("tcp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	listenerDone := make(chan struct{})
+	go func() {
+		defer close(listenerDone)
+		c, err := ln.Accept()
+		if err == nil {
+			c.Close()
+		}
+	}()
+	defer func() { <-listenerDone }()
+	defer ln.Close()
+
+	sawCancel := make(chan bool, 1)
+	testHookCanceledDial = func() {
+		sawCancel <- true
+	}
+
+	ctx, cancelCtx := context.WithCancel(context.Background())
+
+	connectFunc = func(fd int, addr syscall.Sockaddr) error {
+		err := oldConnectFunc(fd, addr)
+		t.Logf("connect(%d, addr) = %v", fd, err)
+		if err == nil {
+			// On some operating systems, localhost
+			// connects _sometimes_ succeed immediately.
+			// Prevent that, so we exercise the code path
+			// we're interested in testing. This seems
+			// harmless. It makes FreeBSD 10.10 work when
+			// run with many iterations. It failed about
+			// half the time previously.
+			return syscall.EINPROGRESS
+		}
+		return err
+	}
+
+	getsockoptIntFunc = func(fd, level, opt int) (val int, err error) {
+		val, err = oldGetsockoptIntFunc(fd, level, opt)
+		t.Logf("getsockoptIntFunc(%d, %d, %d) = (%v, %v)", fd, level, opt, val, err)
+		if level == syscall.SOL_SOCKET && opt == syscall.SO_ERROR && err == nil && val == 0 {
+			t.Logf("canceling context")
+
+			// Cancel the context at just the moment which
+			// caused the race in issue 16523.
+			cancelCtx()
+
+			// And wait for the "interrupter" goroutine to
+			// cancel the dial by messing with its write
+			// timeout before returning.
+			select {
+			case <-sawCancel:
+				t.Logf("saw cancel")
+			case <-time.After(5 * time.Second):
+				t.Errorf("didn't see cancel after 5 seconds")
+			}
+		}
+		return
+	}
+
+	var d Dialer
+	c, err := d.DialContext(ctx, "tcp", ln.Addr().String())
+	if err == nil {
+		c.Close()
+		t.Fatal("unexpected successful dial; want context canceled error")
+	}
+
+	select {
+	case <-ctx.Done():
+	case <-time.After(5 * time.Second):
+		t.Fatal("expected context to be canceled")
+	}
+
+	oe, ok := err.(*OpError)
+	if !ok || oe.Op != "dial" {
+		t.Fatalf("Dial error = %#v; want dial *OpError", err)
+	}
+	if oe.Err != ctx.Err() {
+		t.Errorf("DialContext = (%v, %v); want OpError with error %v", c, err, ctx.Err())
+	}
+}
diff --git a/src/net/fd_unix.go b/src/net/fd_unix.go
index 0f80bc79ac..11dde76977 100644
--- a/src/net/fd_unix.go
+++ b/src/net/fd_unix.go
@@ -64,7 +64,7 @@ func (fd *netFD) name() string {
 	return fd.net + ":" + ls + "->" + rs
 }
 
-func (fd *netFD) connect(ctx context.Context, la, ra syscall.Sockaddr) error {
+func (fd *netFD) connect(ctx context.Context, la, ra syscall.Sockaddr) (ret error) {
 	// Do not need to call fd.writeLock here,
 	// because fd is not yet accessible to user,
 	// so no concurrent operations are possible.
@@ -101,21 +101,44 @@ func (fd *netFD) connect(ctx context.Context, la, ra syscall.Sockaddr) error {
 		defer fd.setWriteDeadline(noDeadline)
 	}
 
-	// Wait for the goroutine converting context.Done into a write timeout
-	// to exist, otherwise our caller might cancel the context and
-	// cause fd.setWriteDeadline(aLongTimeAgo) to cancel a successful dial.
-	done := make(chan bool) // must be unbuffered
-	defer func() { done <- true }()
-	go func() {
-		select {
-		case <-ctx.Done():
-			// Force the runtime's poller to immediately give
-			// up waiting for writability.
-			fd.setWriteDeadline(aLongTimeAgo)
-			<-done
-		case <-done:
-		}
-	}()
+	// Start the "interrupter" goroutine, if this context might be canceled.
+	// (The background context cannot)
+	//
+	// The interrupter goroutine waits for the context to be done and
+	// interrupts the dial (by altering the fd's write deadline, which
+	// wakes up waitWrite).
+	if ctx != context.Background() {
+		// Wait for the interrupter goroutine to exit before returning
+		// from connect.
+		done := make(chan struct{})
+		interruptRes := make(chan error)
+		defer func() {
+			close(done)
+			if ctxErr := <-interruptRes; ctxErr != nil && ret == nil {
+				// The interrupter goroutine called setWriteDeadline,
+				// but the connect code below had returned from
+				// waitWrite already and did a successful connect (ret
+				// == nil). Because we've now poisoned the connection
+				// by making it unwritable, don't return a successful
+				// dial. This was issue 16523.
+				ret = ctxErr
+				fd.Close() // prevent a leak
+			}
+		}()
+		go func() {
+			select {
+			case <-ctx.Done():
+				// Force the runtime's poller to immediately give up
+				// waiting for writability, unblocking waitWrite
+				// below.
+				fd.setWriteDeadline(aLongTimeAgo)
+				testHookCanceledDial()
+				interruptRes <- ctx.Err()
+			case <-done:
+				interruptRes <- nil
+			}
+		}()
+	}
 
 	for {
 		// Performing multiple connect system calls on a
diff --git a/src/net/hook_unix.go b/src/net/hook_unix.go
index 361ca5980c..cf52567fcf 100644
--- a/src/net/hook_unix.go
+++ b/src/net/hook_unix.go
@@ -9,7 +9,8 @@ package net
 import "syscall"
 
 var (
-	testHookDialChannel = func() {} // see golang.org/issue/5349
+	testHookDialChannel  = func() {} // for golang.org/issue/5349
+	testHookCanceledDial = func() {} // for golang.org/issue/16523
 
 	// Placeholders for socket system calls.
 	socketFunc        func(int, int, int) (int, error)         = syscall.Socket