gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/pkg/sync/locking/generic_rwmutex.go (about)

     1  // Copyright 2022 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package locking
    16  
    17  import (
    18  	"reflect"
    19  
    20  	"gvisor.dev/gvisor/pkg/sync"
    21  	"gvisor.dev/gvisor/pkg/sync/locking"
    22  )
    23  
    24  // RWMutex is sync.RWMutex with the correctness validator.
    25  type RWMutex struct {
    26  	mu sync.RWMutex
    27  }
    28  
    29  // lockNames is a list of user-friendly lock names.
    30  // Populated in init.
    31  var lockNames []string
    32  
    33  // lockNameIndex is used as an index passed to NestedLock and NestedUnlock,
    34  // referring to an index within lockNames.
    35  // Values are specified using the "consts" field of go_template_instance.
    36  type lockNameIndex int
    37  
    38  // DO NOT REMOVE: The following function automatically replaced with lock index constants.
    39  // LOCK_NAME_INDEX_CONSTANTS
    40  const ()
    41  
    42  // Lock locks m.
    43  // +checklocksignore
    44  func (m *RWMutex) Lock() {
    45  	locking.AddGLock(genericMarkIndex, -1)
    46  	m.mu.Lock()
    47  }
    48  
    49  // NestedLock locks m knowing that another lock of the same type is held.
    50  // +checklocksignore
    51  func (m *RWMutex) NestedLock(i lockNameIndex) {
    52  	locking.AddGLock(genericMarkIndex, int(i))
    53  	m.mu.Lock()
    54  }
    55  
    56  // Unlock unlocks m.
    57  // +checklocksignore
    58  func (m *RWMutex) Unlock() {
    59  	m.mu.Unlock()
    60  	locking.DelGLock(genericMarkIndex, -1)
    61  }
    62  
    63  // NestedUnlock unlocks m knowing that another lock of the same type is held.
    64  // +checklocksignore
    65  func (m *RWMutex) NestedUnlock(i lockNameIndex) {
    66  	m.mu.Unlock()
    67  	locking.DelGLock(genericMarkIndex, int(i))
    68  }
    69  
    70  // RLock locks m for reading.
    71  // +checklocksignore
    72  func (m *RWMutex) RLock() {
    73  	locking.AddGLock(genericMarkIndex, -1)
    74  	m.mu.RLock()
    75  }
    76  
    77  // RUnlock undoes a single RLock call.
    78  // +checklocksignore
    79  func (m *RWMutex) RUnlock() {
    80  	m.mu.RUnlock()
    81  	locking.DelGLock(genericMarkIndex, -1)
    82  }
    83  
    84  // RLockBypass locks m for reading without executing the validator.
    85  // +checklocksignore
    86  func (m *RWMutex) RLockBypass() {
    87  	m.mu.RLock()
    88  }
    89  
    90  // RUnlockBypass undoes a single RLockBypass call.
    91  // +checklocksignore
    92  func (m *RWMutex) RUnlockBypass() {
    93  	m.mu.RUnlock()
    94  }
    95  
    96  // DowngradeLock atomically unlocks rw for writing and locks it for reading.
    97  // +checklocksignore
    98  func (m *RWMutex) DowngradeLock() {
    99  	m.mu.DowngradeLock()
   100  }
   101  
   102  var genericMarkIndex *locking.MutexClass
   103  
   104  // DO NOT REMOVE: The following function is automatically replaced.
   105  func initLockNames() {}
   106  
   107  func init() {
   108  	initLockNames()
   109  	genericMarkIndex = locking.NewMutexClass(reflect.TypeOf(RWMutex{}), lockNames)
   110  }