From df3c105f49865a48f0c07c79ab84b1bf351a49f8 Mon Sep 17 00:00:00 2001
From: Dean Deng <deandeng@google.com>
Date: Tue, 25 Aug 2020 21:01:45 -0700
Subject: Use new reference count utility throughout gvisor.

This uses the refs_vfs2 template in vfs2 as well as objects common to vfs1 and
vfs2. Note that vfs1-only refcounts are not replaced, since vfs1 will be deleted
soon anyway.

The following structs now use the new tool, with leak check enabled:
devpts:rootInode
fuse:inode
kernfs:Dentry
kernfs:dir
kernfs:readonlyDir
kernfs:StaticDirectory
proc:fdDirInode
proc:fdInfoDirInode
proc:subtasksInode
proc:taskInode
proc:tasksInode
vfs:FileDescription
vfs:MountNamespace
vfs:Filesystem
sys:dir
kernel:FSContext
kernel:ProcessGroup
kernel:Session
shm:Shm
mm:aioMappable
mm:SpecialMappable
transport:queue

And the following use the template, but because they currently are not leak
checked, a TODO is left instead of enabling leak check in this patch:
kernel:FDTable
tun:tunEndpoint

Updates #1486.

PiperOrigin-RevId: 328460377
---
 pkg/sentry/kernel/fd_table.go | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

(limited to 'pkg/sentry/kernel/fd_table.go')

diff --git a/pkg/sentry/kernel/fd_table.go b/pkg/sentry/kernel/fd_table.go
index ce53af69b..5773244ac 100644
--- a/pkg/sentry/kernel/fd_table.go
+++ b/pkg/sentry/kernel/fd_table.go
@@ -23,7 +23,6 @@ import (
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
-	"gvisor.dev/gvisor/pkg/refs"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
@@ -78,7 +77,8 @@ type descriptor struct {
 //
 // +stateify savable
 type FDTable struct {
-	refs.AtomicRefCount
+	FDTableRefs
+
 	k *Kernel
 
 	// mu protects below.
@@ -176,16 +176,15 @@ func (k *Kernel) NewFDTable() *FDTable {
 	return f
 }
 
-// destroy removes all of the file descriptors from the map.
-func (f *FDTable) destroy(ctx context.Context) {
-	f.RemoveIf(ctx, func(*fs.File, *vfs.FileDescription, FDFlags) bool {
-		return true
-	})
-}
-
-// DecRef implements RefCounter.DecRef with destructor f.destroy.
+// DecRef implements RefCounter.DecRef.
+//
+// If f reaches zero references, all of its file descriptors are removed.
 func (f *FDTable) DecRef(ctx context.Context) {
-	f.DecRefWithDestructor(ctx, f.destroy)
+	f.FDTableRefs.DecRef(func() {
+		f.RemoveIf(ctx, func(*fs.File, *vfs.FileDescription, FDFlags) bool {
+			return true
+		})
+	})
 }
 
 // Size returns the number of file descriptor slots currently allocated.
-- 
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