net/http: fix a data race when Request.Cancel is used

The "add a Request.Cancel channel" change (https://golang.org/cl/11601)
added support for "race free" cancellation, but introduced a data race. :)

Noticed while running "go test -race net/http". The test is skipped in
short mode, so we never saw it on the dashboard.

Change-Id: Ica14579d8723f8f9d1691e8d56c30b585b332c64
Reviewed-on: https://go-review.googlesource.com/12663
Reviewed-by: Aaron Jacobs <jacobsa@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/net/http/transport.go b/src/net/http/transport.go
index 41fc6d0e626634fd9b004f971f7bb1bddfb16f6a..41e02fc5802befdc020bf459519967f2d5aafbb9 100644 (file)
--- a/src/net/http/transport.go
+++ b/src/net/http/transport.go
@@ -975,6 +975,7 @@ func (pc *persistConn) readLoop() {
                        // the underlying bufio reader.
                        select {
                        case <-rc.req.Cancel:
+                               alive = false
                                pc.t.CancelRequest(rc.req)
                        case bodyEOF := <-waitForBodyRead:
                                pc.t.setReqCanceler(rc.req, nil) // before pc might return to idle pool