Synchronize signalling with S/R

This is to fix a data race between sending an external signal to
a ThreadGroup and kernel saving state for S/R.

PiperOrigin-RevId: 295244281

1 files changed, 8 insertions, 0 deletions

diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go
index ea21af33f..7da0368f1 100644
--- a/pkg/sentry/kernel/kernel.go
+++ b/pkg/sentry/kernel/kernel.go
@@ -1169,6 +1169,14 @@ func (k *Kernel) SendExternalSignal(info *arch.SignalInfo, context string) {
 	k.sendExternalSignal(info, context)
 }
 
+// SendExternalSignalThreadGroup injects a signal into an specific ThreadGroup.
+// This function doesn't skip signals like SendExternalSignal does.
+func (k *Kernel) SendExternalSignalThreadGroup(tg *ThreadGroup, info *arch.SignalInfo) error {
+	k.extMu.Lock()
+	defer k.extMu.Unlock()
+	return tg.SendSignal(info)
+}
+
 // SendContainerSignal sends the given signal to all processes inside the
 // namespace that match the given container ID.
 func (k *Kernel) SendContainerSignal(cid string, info *arch.SignalInfo) error {