diff options
Diffstat (limited to 'pkg/refs_vfs2')
| -rw-r--r-- | pkg/refs_vfs2/BUILD | 28 | ||||
| -rw-r--r-- | pkg/refs_vfs2/refs.go | 36 | ||||
| -rw-r--r-- | pkg/refs_vfs2/refs_template.go | 133 |
3 files changed, 0 insertions, 197 deletions
diff --git a/pkg/refs_vfs2/BUILD b/pkg/refs_vfs2/BUILD deleted file mode 100644 index 7f180c7bd..000000000 --- a/pkg/refs_vfs2/BUILD +++ /dev/null @@ -1,28 +0,0 @@ -load("//tools:defs.bzl", "go_library") -load("//tools/go_generics:defs.bzl", "go_template") - -package(licenses = ["notice"]) - -go_template( - name = "refs_template", - srcs = [ - "refs_template.go", - ], - types = [ - "T", - ], - visibility = ["//pkg/sentry:internal"], - deps = [ - "//pkg/log", - "//pkg/refs", - ], -) - -go_library( - name = "refs", - srcs = [ - "refs.go", - ], - visibility = ["//pkg/sentry:internal"], - deps = ["//pkg/context"], -) diff --git a/pkg/refs_vfs2/refs.go b/pkg/refs_vfs2/refs.go deleted file mode 100644 index ee01b17b0..000000000 --- a/pkg/refs_vfs2/refs.go +++ /dev/null @@ -1,36 +0,0 @@ -// Copyright 2020 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// Package refs defines an interface for a reference-counted object. -package refs - -import ( - "gvisor.dev/gvisor/pkg/context" -) - -// RefCounter is the interface to be implemented by objects that are reference -// counted. -type RefCounter interface { - // IncRef increments the reference counter on the object. - IncRef() - - // DecRef decrements the object's reference count. Users of refs_template.Refs - // may specify a destructor to be called once the reference count reaches zero. - DecRef(ctx context.Context) - - // TryIncRef attempts to increment the reference count, but may fail if all - // references have already been dropped, in which case it returns false. If - // true is returned, then a valid reference is now held on the object. - TryIncRef() bool -} diff --git a/pkg/refs_vfs2/refs_template.go b/pkg/refs_vfs2/refs_template.go deleted file mode 100644 index 99c43c065..000000000 --- a/pkg/refs_vfs2/refs_template.go +++ /dev/null @@ -1,133 +0,0 @@ -// Copyright 2020 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// Package refs_template defines a template that can be used by reference counted -// objects. -package refs_template - -import ( - "runtime" - "sync/atomic" - - "gvisor.dev/gvisor/pkg/log" - refs_vfs1 "gvisor.dev/gvisor/pkg/refs" -) - -// T is the type of the reference counted object. It is only used to customize -// debug output when leak checking. -type T interface{} - -// ownerType is used to customize logging. Note that we use a pointer to T so -// that we do not copy the entire object when passed as a format parameter. -var ownerType *T - -// 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 Refs struct { - // refCount is composed of two fields: - // - // [32-bit speculative references]:[32-bit real references] - // - // Speculative references are used for TryIncRef, to avoid a CompareAndSwap - // loop. See IncRef, DecRef and TryIncRef for details of how these fields are - // used. - refCount int64 -} - -func (r *Refs) finalize() { - var note string - switch refs_vfs1.GetLeakMode() { - case refs_vfs1.NoLeakChecking: - return - case refs_vfs1.UninitializedLeakChecking: - note = "(Leak checker uninitialized): " - } - if n := r.ReadRefs(); n != 0 { - log.Warningf("%sRefs %p owned by %T garbage collected with ref count of %d (want 0)", note, r, ownerType, n) - } -} - -// EnableLeakCheck checks for reference leaks when Refs gets garbage collected. -func (r *Refs) EnableLeakCheck() { - if refs_vfs1.GetLeakMode() != refs_vfs1.NoLeakChecking { - runtime.SetFinalizer(r, (*Refs).finalize) - } -} - -// ReadRefs returns the current number of references. The returned count is -// inherently racy and is unsafe to use without external synchronization. -func (r *Refs) ReadRefs() int64 { - // Account for the internal -1 offset on refcounts. - return atomic.LoadInt64(&r.refCount) + 1 -} - -// IncRef implements refs.RefCounter.IncRef. -// -//go:nosplit -func (r *Refs) IncRef() { - if v := atomic.AddInt64(&r.refCount, 1); v <= 0 { - panic("Incrementing non-positive ref count") - } -} - -// TryIncRef implements refs.RefCounter.TryIncRef. -// -// To do this safely without a loop, a speculative reference is first acquired -// on the object. This allows multiple concurrent TryIncRef calls to distinguish -// other TryIncRef calls from genuine references held. -// -//go:nosplit -func (r *Refs) TryIncRef() bool { - const speculativeRef = 1 << 32 - v := atomic.AddInt64(&r.refCount, speculativeRef) - if int32(v) < 0 { - // This object has already been freed. - atomic.AddInt64(&r.refCount, -speculativeRef) - return false - } - - // Turn into a real reference. - atomic.AddInt64(&r.refCount, -speculativeRef+1) - return true -} - -// DecRef implements refs.RefCounter.DecRef. -// -// Note that speculative references are counted here. Since they were added -// prior to real references reaching zero, they will successfully convert to -// real references. In other words, we see speculative references only in the -// following case: -// -// A: TryIncRef [speculative increase => sees non-negative references] -// B: DecRef [real decrease] -// A: TryIncRef [transform speculative to real] -// -//go:nosplit -func (r *Refs) DecRef(destroy func()) { - switch v := atomic.AddInt64(&r.refCount, -1); { - case v < -1: - panic("Decrementing non-positive ref count") - - case v == -1: - // Call the destructor. - if destroy != nil { - destroy() - } - } -} |