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authornybidari <59618317+nybidari@users.noreply.github.com>2020-02-25 15:33:59 -0800
committerGitHub <noreply@github.com>2020-02-25 15:33:59 -0800
commit818abc2bd5096bf7dc6f621cfd2923bee4e0fc7b (patch)
tree0f7f90cecb6afc332a3229651eba4da391a46b41 /pkg/sentry/platform
parentacc405ba60834f5dce9ce04cd762d5cda02224cb (diff)
parent72e3f3a3eef3a1dc02db0ff71f98a5d7fe89a6e3 (diff)
Merge branch 'master' into iptables
Diffstat (limited to 'pkg/sentry/platform')
-rw-r--r--pkg/sentry/platform/kvm/machine.go18
1 files changed, 17 insertions, 1 deletions
diff --git a/pkg/sentry/platform/kvm/machine.go b/pkg/sentry/platform/kvm/machine.go
index 8076c7529..f1afc74dc 100644
--- a/pkg/sentry/platform/kvm/machine.go
+++ b/pkg/sentry/platform/kvm/machine.go
@@ -329,10 +329,12 @@ func (m *machine) Destroy() {
}
// Get gets an available vCPU.
+//
+// This will return with the OS thread locked.
func (m *machine) Get() *vCPU {
+ m.mu.RLock()
runtime.LockOSThread()
tid := procid.Current()
- m.mu.RLock()
// Check for an exact match.
if c := m.vCPUs[tid]; c != nil {
@@ -343,8 +345,22 @@ func (m *machine) Get() *vCPU {
// The happy path failed. We now proceed to acquire an exclusive lock
// (because the vCPU map may change), and scan all available vCPUs.
+ // In this case, we first unlock the OS thread. Otherwise, if mu is
+ // not available, the current system thread will be parked and a new
+ // system thread spawned. We avoid this situation by simply refreshing
+ // tid after relocking the system thread.
m.mu.RUnlock()
+ runtime.UnlockOSThread()
m.mu.Lock()
+ runtime.LockOSThread()
+ tid = procid.Current()
+
+ // Recheck for an exact match.
+ if c := m.vCPUs[tid]; c != nil {
+ c.lock()
+ m.mu.Unlock()
+ return c
+ }
for {
// Scan for an available vCPU.