Remove error return from AddressSpace.Release()

PiperOrigin-RevId: 196291289
Change-Id: Ie3487be029850b0b410b82416750853a6c4a2b00

pkg/sentry/kernel/task_usermem.go

@@ -39,9 +39,7 @@ func (t *Task) Activate() {
 // Deactivate relinquishes the task's active address space.
 func (t *Task) Deactivate() {
 	if mm := t.MemoryManager(); mm != nil {
-		if err := mm.Deactivate(); err != nil {
-			panic("unable to deactivate mm: " + err.Error())
-		}
+		mm.Deactivate()
 	}
 }
 

pkg/sentry/mm/address_space.go

@@ -114,12 +114,12 @@ func (mm *MemoryManager) Activate() error {
 	}
 }
 
-// Deactivate releases a release to the MemoryManager.
-func (mm *MemoryManager) Deactivate() error {
+// Deactivate releases a reference to the MemoryManager.
+func (mm *MemoryManager) Deactivate() {
 	// Fast path: this is not the last goroutine to deactivate the
 	// MemoryManager.
 	if atomicbitops.DecUnlessOneInt32(&mm.active) {
-		return nil
+		return
 	}
 
 	mm.activeMu.Lock()
@@ -128,26 +128,21 @@ func (mm *MemoryManager) Deactivate() error {
 	// Still active?
 	if atomic.AddInt32(&mm.active, -1) > 0 {
 		mm.activeMu.Unlock()
-		return nil
+		return
 	}
 
 	// Can we hold on to the address space?
 	if !mm.p.CooperativelySchedulesAddressSpace() {
 		mm.activeMu.Unlock()
-		return nil
+		return
 	}
 
 	// Release the address space.
-	if err := mm.as.Release(); err != nil {
-		atomic.StoreInt32(&mm.active, 1)
-		mm.activeMu.Unlock()
-		return err
-	}
+	mm.as.Release()
 
 	// Lost it.
 	mm.as = nil
 	mm.activeMu.Unlock()
-	return nil
 }
 
 // mapASLocked maps addresses in ar into mm.as. If precommit is true, mappings

pkg/sentry/platform/kvm/address_space.go

@@ -200,8 +200,7 @@ func (as *addressSpace) Unmap(addr usermem.Addr, length uint64) {
 }
 
 // Release releases the page tables.
-func (as *addressSpace) Release() error {
+func (as *addressSpace) Release() {
 	as.Unmap(0, ^uint64(0))
 	as.pageTables.Release()
-	return nil
 }

pkg/sentry/platform/platform.go

@@ -205,7 +205,7 @@ type AddressSpace interface {
 
 	// Release releases this address space. After releasing, a new AddressSpace
 	// must be acquired via platform.NewAddressSpace().
-	Release() error
+	Release()
 
 	// AddressSpaceIO methods are supported iff the associated platform's
 	// Platform.SupportsAddressSpaceIO() == true. AddressSpaces for which this

pkg/sentry/platform/ptrace/subprocess.go

@@ -242,14 +242,13 @@ func (s *subprocess) unmap() {
 // Therefore we simply unmap everything in the subprocess and return it to the
 // globalPool. This has the added benefit of reducing creation time for new
 // subprocesses.
-func (s *subprocess) Release() error {
+func (s *subprocess) Release() {
 	go func() { // S/R-SAFE: Platform.
 		s.unmap()
 		globalPool.mu.Lock()
 		globalPool.available = append(globalPool.available, s)
 		globalPool.mu.Unlock()
 	}()
-	return nil
 }
 
 // newThread creates a new traced thread.