/
lockdep.go
136 lines (118 loc) · 3.79 KB
/
lockdep.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
// Copyright 2022 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.
//go:build lockdep
// +build lockdep
package locking
import (
"fmt"
"reflect"
"strings"
"gvisor.dev/gvisor/pkg/goid"
"gvisor.dev/gvisor/pkg/log"
)
var classMap classAtomicPtrMap
// NewMutexClass allocates a new mutex class.
func NewMutexClass(t reflect.Type) *MutexClass {
c := &MutexClass{}
classMap.Store(c, &t)
return c
}
// MutexClass describes dependencies of a specific class.
type MutexClass struct {
// ancestors are locks that are locked before the current class.
ancestors ancestorsAtomicPtrMap
// subclasses is the list of sub-classes that are used to handle nested locks.
subclasses subclassAtomicPtrMap
}
type goroutineLocks map[*MutexClass]bool
var routineLocks goroutineLocksAtomicPtrMap
// checkLock checks that class isn't in ancestors of prevClass.
func checkLock(class *MutexClass, prevClass *MutexClass, chain []*MutexClass) {
chain = append(chain, prevClass)
if c := prevClass.ancestors.Load(class); c != nil {
var b strings.Builder
fmt.Fprintf(&b, "WARNING: circular locking detected: %s -> %s:\n%s\n",
*classMap.Load(chain[0]), *classMap.Load(class), log.Stacks(false))
fmt.Fprintf(&b, "known lock chain: ")
c := class
for i := len(chain) - 1; i >= 0; i-- {
fmt.Fprintf(&b, "%s -> ", *classMap.Load(c))
c = chain[i]
}
fmt.Fprintf(&b, "%s\n", *classMap.Load(chain[0]))
c = class
for i := len(chain) - 1; i >= 0; i-- {
fmt.Fprintf(&b, "\n====== %s -> %s =====\n%s",
*classMap.Load(c), *classMap.Load(chain[i]), *chain[i].ancestors.Load(c))
c = chain[i]
}
panic(b.String())
}
prevClass.ancestors.RangeRepeatable(func(parentClass *MutexClass, stacks *string) bool {
// The recursion is fine here. If it fails, you need to reduce
// a number of nested locks.
checkLock(class, parentClass, chain)
return true
})
}
// AddGLock records a lock to the current goroutine and updates dependences.
func AddGLock(class *MutexClass, subclass uint32) {
gid := goid.Get()
if subclass != 0 {
var c *MutexClass
if c = class.subclasses.Load(subclass); c == nil {
t := classMap.Load(class)
c = NewMutexClass(*t)
class.subclasses.Store(subclass, c)
}
class = c
}
currentLocks := routineLocks.Load(gid)
if currentLocks == nil {
locks := goroutineLocks(make(map[*MutexClass]bool))
locks[class] = true
routineLocks.Store(gid, &locks)
return
}
// Check dependencies and add locked mutexes to the ancestors list.
for prevClass := range *currentLocks {
if prevClass == class {
panic(fmt.Sprintf("nested locking: %s:\n%s", *classMap.Load(class), log.Stacks(false)))
}
checkLock(class, prevClass, nil)
if c := class.ancestors.Load(prevClass); c == nil {
stacks := string(log.Stacks(false))
class.ancestors.Store(prevClass, &stacks)
}
}
(*currentLocks)[class] = true
}
// DelGLock deletes a lock from the current goroutine.
func DelGLock(class *MutexClass, subclass uint32) {
if subclass != 0 {
class = class.subclasses.Load(subclass)
}
gid := goid.Get()
currentLocks := routineLocks.Load(gid)
if currentLocks == nil {
panic("the current goroutine doesn't have locks")
}
if _, ok := (*currentLocks)[class]; !ok {
panic("unlock of an unknown lock")
}
delete(*currentLocks, class)
if len(*currentLocks) == 0 {
routineLocks.Store(gid, nil)
}
}