Merge release-20201030.0-53-g0fb5353e4 (automated)

4 files changed, 55 insertions, 29 deletions

diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index d83c17f83..eac578f25 100644
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -660,7 +660,7 @@ var _ Inode = (*StaticDirectory)(nil)
 func NewStaticDir(ctx context.Context, creds *auth.Credentials, devMajor, devMinor uint32, ino uint64, perm linux.FileMode, children map[string]Inode, fdOpts GenericDirectoryFDOptions) Inode {
 	inode := &StaticDirectory{}
 	inode.Init(ctx, creds, devMajor, devMinor, ino, perm, fdOpts)
-	inode.EnableLeakCheck()
+	inode.InitRefs()
 
 	inode.OrderedChildren.Init(OrderedChildrenOptions{})
 	links := inode.OrderedChildren.Populate(children)
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go
index abb477c7d..c14abcff4 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs.go
@@ -222,7 +222,9 @@ func (d *Dentry) IncRef() {
 	// d.refs may be 0 if d.fs.mu is locked, which serializes against
 	// d.cacheLocked().
 	r := atomic.AddInt64(&d.refs, 1)
-	refsvfs2.LogIncRef(d, r)
+	if d.LogRefs() {
+		refsvfs2.LogIncRef(d, r)
+	}
 }
 
 // TryIncRef implements vfs.DentryImpl.TryIncRef.
@@ -233,7 +235,9 @@ func (d *Dentry) TryIncRef() bool {
 			return false
 		}
 		if atomic.CompareAndSwapInt64(&d.refs, r, r+1) {
-			refsvfs2.LogTryIncRef(d, r+1)
+			if d.LogRefs() {
+				refsvfs2.LogTryIncRef(d, r+1)
+			}
 			return true
 		}
 	}
@@ -242,7 +246,9 @@ func (d *Dentry) TryIncRef() bool {
 // DecRef implements vfs.DentryImpl.DecRef.
 func (d *Dentry) DecRef(ctx context.Context) {
 	r := atomic.AddInt64(&d.refs, -1)
-	refsvfs2.LogDecRef(d, r)
+	if d.LogRefs() {
+		refsvfs2.LogDecRef(d, r)
+	}
 	if r == 0 {
 		d.fs.mu.Lock()
 		d.cacheLocked(ctx)
@@ -254,7 +260,9 @@ func (d *Dentry) DecRef(ctx context.Context) {
 
 func (d *Dentry) decRefLocked(ctx context.Context) {
 	r := atomic.AddInt64(&d.refs, -1)
-	refsvfs2.LogDecRef(d, r)
+	if d.LogRefs() {
+		refsvfs2.LogDecRef(d, r)
+	}
 	if r == 0 {
 		d.cacheLocked(ctx)
 	} else if r < 0 {
diff --git a/pkg/sentry/fsimpl/kernfs/static_directory_refs.go b/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
index d86cf76fe..cdf6374a3 100644
--- a/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
+++ b/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
@@ -20,9 +20,6 @@ var StaticDirectoryobj *StaticDirectory
 // Refs implements refs.RefCounter. It keeps a reference count using atomic
 // operations and calls the destructor when the count reaches zero.
 //
-// Note that the number of references is actually refCount + 1 so that a default
-// zero-value Refs object contains one reference.
-//
 // +stateify savable
 type StaticDirectoryRefs struct {
 	// refCount is composed of two fields:
@@ -35,6 +32,13 @@ type StaticDirectoryRefs struct {
 	refCount int64
 }
 
+// InitRefs initializes r with one reference and, if enabled, activates leak
+// checking.
+func (r *StaticDirectoryRefs) InitRefs() {
+	atomic.StoreInt64(&r.refCount, 1)
+	refsvfs2.Register(r)
+}
+
 // RefType implements refsvfs2.CheckedObject.RefType.
 func (r *StaticDirectoryRefs) RefType() string {
 	return fmt.Sprintf("%T", StaticDirectoryobj)[1:]
@@ -58,8 +62,7 @@ func (r *StaticDirectoryRefs) EnableLeakCheck() {
 // ReadRefs returns the current number of references. The returned count is
 // inherently racy and is unsafe to use without external synchronization.
 func (r *StaticDirectoryRefs) ReadRefs() int64 {
-
-	return atomic.LoadInt64(&r.refCount) + 1
+	return atomic.LoadInt64(&r.refCount)
 }
 
 // IncRef implements refs.RefCounter.IncRef.
@@ -67,8 +70,10 @@ func (r *StaticDirectoryRefs) ReadRefs() int64 {
 //go:nosplit
 func (r *StaticDirectoryRefs) IncRef() {
 	v := atomic.AddInt64(&r.refCount, 1)
-	refsvfs2.LogIncRef(r, v+1)
-	if v <= 0 {
+	if StaticDirectoryenableLogging {
+		refsvfs2.LogIncRef(r, v)
+	}
+	if v <= 1 {
 		panic(fmt.Sprintf("Incrementing non-positive count %p on %s", r, r.RefType()))
 	}
 }
@@ -82,14 +87,16 @@ func (r *StaticDirectoryRefs) IncRef() {
 //go:nosplit
 func (r *StaticDirectoryRefs) TryIncRef() bool {
 	const speculativeRef = 1 << 32
-	if v := atomic.AddInt64(&r.refCount, speculativeRef); int32(v) < 0 {
+	if v := atomic.AddInt64(&r.refCount, speculativeRef); int32(v) == 0 {
 
 		atomic.AddInt64(&r.refCount, -speculativeRef)
 		return false
 	}
 
 	v := atomic.AddInt64(&r.refCount, -speculativeRef+1)
-	refsvfs2.LogTryIncRef(r, v+1)
+	if StaticDirectoryenableLogging {
+		refsvfs2.LogTryIncRef(r, v)
+	}
 	return true
 }
 
@@ -107,12 +114,14 @@ func (r *StaticDirectoryRefs) TryIncRef() bool {
 //go:nosplit
 func (r *StaticDirectoryRefs) DecRef(destroy func()) {
 	v := atomic.AddInt64(&r.refCount, -1)
-	refsvfs2.LogDecRef(r, v+1)
+	if StaticDirectoryenableLogging {
+		refsvfs2.LogDecRef(r, v+1)
+	}
 	switch {
-	case v < -1:
+	case v < 0:
 		panic(fmt.Sprintf("Decrementing non-positive ref count %p, owned by %s", r, r.RefType()))
 
-	case v == -1:
+	case v == 0:
 		refsvfs2.Unregister(r)
 
 		if destroy != nil {
diff --git a/pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go b/pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go
index 446837e30..69b41668a 100644
--- a/pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go
+++ b/pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go
@@ -20,9 +20,6 @@ var syntheticDirectoryobj *syntheticDirectory
 // Refs implements refs.RefCounter. It keeps a reference count using atomic
 // operations and calls the destructor when the count reaches zero.
 //
-// Note that the number of references is actually refCount + 1 so that a default
-// zero-value Refs object contains one reference.
-//
 // +stateify savable
 type syntheticDirectoryRefs struct {
 	// refCount is composed of two fields:
@@ -35,6 +32,13 @@ type syntheticDirectoryRefs struct {
 	refCount int64
 }
 
+// InitRefs initializes r with one reference and, if enabled, activates leak
+// checking.
+func (r *syntheticDirectoryRefs) InitRefs() {
+	atomic.StoreInt64(&r.refCount, 1)
+	refsvfs2.Register(r)
+}
+
 // RefType implements refsvfs2.CheckedObject.RefType.
 func (r *syntheticDirectoryRefs) RefType() string {
 	return fmt.Sprintf("%T", syntheticDirectoryobj)[1:]
@@ -58,8 +62,7 @@ func (r *syntheticDirectoryRefs) EnableLeakCheck() {
 // ReadRefs returns the current number of references. The returned count is
 // inherently racy and is unsafe to use without external synchronization.
 func (r *syntheticDirectoryRefs) ReadRefs() int64 {
-
-	return atomic.LoadInt64(&r.refCount) + 1
+	return atomic.LoadInt64(&r.refCount)
 }
 
 // IncRef implements refs.RefCounter.IncRef.
@@ -67,8 +70,10 @@ func (r *syntheticDirectoryRefs) ReadRefs() int64 {
 //go:nosplit
 func (r *syntheticDirectoryRefs) IncRef() {
 	v := atomic.AddInt64(&r.refCount, 1)
-	refsvfs2.LogIncRef(r, v+1)
-	if v <= 0 {
+	if syntheticDirectoryenableLogging {
+		refsvfs2.LogIncRef(r, v)
+	}
+	if v <= 1 {
 		panic(fmt.Sprintf("Incrementing non-positive count %p on %s", r, r.RefType()))
 	}
 }
@@ -82,14 +87,16 @@ func (r *syntheticDirectoryRefs) IncRef() {
 //go:nosplit
 func (r *syntheticDirectoryRefs) TryIncRef() bool {
 	const speculativeRef = 1 << 32
-	if v := atomic.AddInt64(&r.refCount, speculativeRef); int32(v) < 0 {
+	if v := atomic.AddInt64(&r.refCount, speculativeRef); int32(v) == 0 {
 
 		atomic.AddInt64(&r.refCount, -speculativeRef)
 		return false
 	}
 
 	v := atomic.AddInt64(&r.refCount, -speculativeRef+1)
-	refsvfs2.LogTryIncRef(r, v+1)
+	if syntheticDirectoryenableLogging {
+		refsvfs2.LogTryIncRef(r, v)
+	}
 	return true
 }
 
@@ -107,12 +114,14 @@ func (r *syntheticDirectoryRefs) TryIncRef() bool {
 //go:nosplit
 func (r *syntheticDirectoryRefs) DecRef(destroy func()) {
 	v := atomic.AddInt64(&r.refCount, -1)
-	refsvfs2.LogDecRef(r, v+1)
+	if syntheticDirectoryenableLogging {
+		refsvfs2.LogDecRef(r, v+1)
+	}
 	switch {
-	case v < -1:
+	case v < 0:
 		panic(fmt.Sprintf("Decrementing non-positive ref count %p, owned by %s", r, r.RefType()))
 
-	case v == -1:
+	case v == 0:
 		refsvfs2.Unregister(r)
 
 		if destroy != nil {