use atomicbitops, not sync/atomic, in refsvfs2

Since refsvfs2 are used in netstack, we should use atomicbitops to avoid
breaking 32-bit builds.

On 64-bit builds there is no performance difference.

PiperOrigin-RevId: 439687980

pkg/lisafs/BUILD

@@ -88,6 +88,7 @@ go_library(
     marshal = True,
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/cleanup",
         "//pkg/context",
         "//pkg/fdchannel",

pkg/refsvfs2/refs_template.go

@@ -18,8 +18,8 @@ package refs_template
 
 import (
 	"fmt"
-	"sync/atomic"
 
+	"gvisor.dev/gvisor/pkg/atomicbitops"
 	"gvisor.dev/gvisor/pkg/refsvfs2"
 )
 
@@ -57,13 +57,13 @@ type Refs struct {
 	// 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
+	refCount atomicbitops.AlignedAtomicInt64
 }
 
 // InitRefs initializes r with one reference and, if enabled, activates leak
 // checking.
 func (r *Refs) InitRefs() {
-	atomic.StoreInt64(&r.refCount, 1)
+	r.refCount.Store(1)
 	refsvfs2.Register(r)
 }
 
@@ -85,14 +85,14 @@ func (r *Refs) LogRefs() bool {
 // 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 {
-	return atomic.LoadInt64(&r.refCount)
+	return r.refCount.Load()
 }
 
 // IncRef implements refs.RefCounter.IncRef.
 //
 //go:nosplit
 func (r *Refs) IncRef() {
-	v := atomic.AddInt64(&r.refCount, 1)
+	v := r.refCount.Add(1)
 	if enableLogging {
 		refsvfs2.LogIncRef(r, v)
 	}
@@ -110,14 +110,14 @@ func (r *Refs) IncRef() {
 //go:nosplit
 func (r *Refs) TryIncRef() bool {
 	const speculativeRef = 1 << 32
-	if v := atomic.AddInt64(&r.refCount, speculativeRef); int32(v) == 0 {
+	if v := r.refCount.Add(speculativeRef); int32(v) == 0 {
 		// This object has already been freed.
-		atomic.AddInt64(&r.refCount, -speculativeRef)
+		r.refCount.Add(-speculativeRef)
 		return false
 	}
 
 	// Turn into a real reference.
-	v := atomic.AddInt64(&r.refCount, -speculativeRef+1)
+	v := r.refCount.Add(-speculativeRef + 1)
 	if enableLogging {
 		refsvfs2.LogTryIncRef(r, v)
 	}
@@ -137,7 +137,7 @@ func (r *Refs) TryIncRef() bool {
 //
 //go:nosplit
 func (r *Refs) DecRef(destroy func()) {
-	v := atomic.AddInt64(&r.refCount, -1)
+	v := r.refCount.Add(-1)
 	if enableLogging {
 		refsvfs2.LogDecRef(r, v)
 	}

pkg/sentry/fsimpl/cgroupfs/BUILD

@@ -30,6 +30,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/bitmap",
         "//pkg/context",
         "//pkg/coverage",

pkg/sentry/fsimpl/devpts/BUILD

@@ -28,6 +28,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/log",

pkg/sentry/fsimpl/fuse/BUILD

@@ -46,6 +46,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/hostarch",

pkg/sentry/fsimpl/host/BUILD

@@ -29,6 +29,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/fdnotifier",

pkg/sentry/fsimpl/kernfs/BUILD

@@ -103,6 +103,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/fspath",
@@ -134,6 +135,7 @@ go_test(
     deps = [
         ":kernfs",
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/fspath",

pkg/sentry/fsimpl/mqfs/BUILD

@@ -26,6 +26,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/refsvfs2",

pkg/sentry/fsimpl/proc/BUILD

@@ -80,6 +80,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/hostarch",

pkg/sentry/fsimpl/sys/BUILD

@@ -24,6 +24,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/coverage",
         "//pkg/errors/linuxerr",

pkg/sentry/fsimpl/tmpfs/BUILD

@@ -56,6 +56,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/fspath",

pkg/sentry/kernel/BUILD

@@ -220,6 +220,7 @@ go_library(
         "//pkg/abi",
         "//pkg/abi/linux",
         "//pkg/abi/linux/errno",
+        "//pkg/atomicbitops",
         "//pkg/bitmap",
         "//pkg/bits",
         "//pkg/bpf",

pkg/sentry/kernel/shm/BUILD

@@ -27,6 +27,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/hostarch",

pkg/sentry/socket/unix/BUILD

@@ -38,6 +38,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/fspath",

pkg/sentry/socket/unix/transport/BUILD

@@ -57,6 +57,7 @@ go_library(
     visibility = ["//:sandbox"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/fdnotifier",

pkg/sentry/vfs/BUILD

@@ -94,6 +94,7 @@ go_library(
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/fd",

pkg/tcpip/link/tun/BUILD

@@ -25,6 +25,7 @@ go_library(
     visibility = ["//visibility:public"],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/atomicbitops",
         "//pkg/context",
         "//pkg/errors/linuxerr",
         "//pkg/log",

pkg/tcpip/transport/tcp/BUILD

@@ -71,6 +71,7 @@ go_library(
     imports = ["gvisor.dev/gvisor/pkg/tcpip/buffer"],
     visibility = ["//visibility:public"],
     deps = [
+        "//pkg/atomicbitops",
         "//pkg/log",
         "//pkg/rand",
         "//pkg/refsvfs2",