gvisor: lockless read access for task credentials

Credentials are immutable and even before these changes we could read them
without locks, but we needed to take a task lock to get a credential object
from a task object.

It is possible to avoid this lock, if we will guarantee that a credential
object will not be changed after setting it on a task.

PiperOrigin-RevId: 254989492

1 files changed, 11 insertions, 1 deletions

diff --git a/third_party/gvsync/atomicptr_unsafe.go b/third_party/gvsync/atomicptr_unsafe.go
index 53a943282..525c4beed 100644
--- a/third_party/gvsync/atomicptr_unsafe.go
+++ b/third_party/gvsync/atomicptr_unsafe.go
@@ -21,8 +21,18 @@ type Value struct{}
 // Note that copying AtomicPtr by value performs a non-atomic read of the
 // stored pointer, which is unsafe if Store() can be called concurrently; in
 // this case, do `dst.Store(src.Load())` instead.
+//
+// +stateify savable
 type AtomicPtr struct {
-	ptr unsafe.Pointer
+	ptr unsafe.Pointer `state:".(*Value)"`
+}
+
+func (p *AtomicPtr) savePtr() *Value {
+	return p.Load()
+}
+
+func (p *AtomicPtr) loadPtr(v *Value) {
+	p.Store(v)
 }
 
 // Load returns the value set by the most recent Store. It returns nil if there