vm/vmimpl: add vm.Diagnose method

Diagnose is called on machine hang to try to get
some additional diagnostic information from it.
For now it's all stubs.

7 files changed, 35 insertions, 0 deletions

diff --git a/vm/adb/adb.go b/vm/adb/adb.go
index 3b839ea00..91bef1e0f 100644
--- a/vm/adb/adb.go
+++ b/vm/adb/adb.go
@@ -428,3 +428,7 @@ func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command strin
 
 	return vmimpl.Multiplex(adb, merger, tty, timeout, stop, inst.closed, inst.debug)
 }
+
+func (inst *instance) Diagnose() bool {
+	return false
+}
diff --git a/vm/gce/gce.go b/vm/gce/gce.go
index dbd1001fd..b715c4afb 100644
--- a/vm/gce/gce.go
+++ b/vm/gce/gce.go
@@ -350,6 +350,10 @@ func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command strin
 	return merger.Output, errc, nil
 }
 
+func (inst *instance) Diagnose() bool {
+	return false
+}
+
 func (pool *Pool) waitInstanceBoot(name, ip, sshKey, sshUser, gceKey string) error {
 	pwd := "pwd"
 	if pool.env.OS == "windows" {
diff --git a/vm/isolated/isolated.go b/vm/isolated/isolated.go
index f86ec96fd..6c79f7cd6 100644
--- a/vm/isolated/isolated.go
+++ b/vm/isolated/isolated.go
@@ -308,6 +308,10 @@ func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command strin
 	return vmimpl.Multiplex(cmd, merger, dmesg, timeout, stop, inst.closed, inst.debug)
 }
 
+func (inst *instance) Diagnose() bool {
+	return false
+}
+
 func (inst *instance) sshArgs(portArg string) []string {
 	args := []string{
 		portArg, fmt.Sprint(inst.targetPort),
diff --git a/vm/kvm/kvm.go b/vm/kvm/kvm.go
index 7911936e3..68604ae98 100644
--- a/vm/kvm/kvm.go
+++ b/vm/kvm/kvm.go
@@ -285,6 +285,10 @@ func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command strin
 	return outputC, errorC, nil
 }
 
+func (inst *instance) Diagnose() bool {
+	return false
+}
+
 const script = `#! /bin/bash
 while true; do
 	if [ -e "/syz-cmd" ]; then
diff --git a/vm/qemu/qemu.go b/vm/qemu/qemu.go
index 135f11235..189d3e13c 100644
--- a/vm/qemu/qemu.go
+++ b/vm/qemu/qemu.go
@@ -487,6 +487,10 @@ func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command strin
 	return inst.merger.Output, errc, nil
 }
 
+func (inst *instance) Diagnose() bool {
+	return false
+}
+
 func (inst *instance) sshArgs(portArg string) []string {
 	args := []string{
 		portArg, strconv.Itoa(inst.port),
diff --git a/vm/vm.go b/vm/vm.go
index ff283cd2f..7082011dd 100644
--- a/vm/vm.go
+++ b/vm/vm.go
@@ -97,6 +97,10 @@ func (inst *Instance) Run(timeout time.Duration, stop <-chan bool, command strin
 	return inst.impl.Run(timeout, stop, command)
 }
 
+func (inst *Instance) Diagnose() bool {
+	return inst.impl.Diagnose()
+}
+
 func (inst *Instance) Close() {
 	inst.impl.Close()
 	os.RemoveAll(inst.workdir)
@@ -217,6 +221,9 @@ func (inst *Instance) MonitorExecution(outc <-chan []byte, errc <-chan error,
 			// We intentionally produce the same title as no output at all,
 			// because frequently it's the same condition.
 			if time.Since(lastExecuteTime) > 3*time.Minute {
+				if inst.Diagnose() {
+					waitForOutput()
+				}
 				rep := &report.Report{
 					Title:  "no output from test machine",
 					Output: output,
@@ -225,6 +232,9 @@ func (inst *Instance) MonitorExecution(outc <-chan []byte, errc <-chan error,
 			}
 		case <-ticker.C:
 			tickerFired = true
+			if inst.Diagnose() {
+				waitForOutput()
+			}
 			rep := &report.Report{
 				Title:  "no output from test machine",
 				Output: output,
diff --git a/vm/vmimpl/vmimpl.go b/vm/vmimpl/vmimpl.go
index 532611abd..7d3411ee9 100644
--- a/vm/vmimpl/vmimpl.go
+++ b/vm/vmimpl/vmimpl.go
@@ -43,6 +43,11 @@ type Instance interface {
 	// Command is terminated after timeout. Send on the stop chan can be used to terminate it earlier.
 	Run(timeout time.Duration, stop <-chan bool, command string) (outc <-chan []byte, errc <-chan error, err error)
 
+	// Diagnose forces VM to dump additional debugging info
+	// (e.g. sending some sys-rq's or SIGABORT'ing a Go program).
+	// Returns true if it did anything.
+	Diagnose() bool
+
 	// Close stops and destroys the VM.
 	Close()
 }