Support distinction for RWMutex and read-only locks.

Fixes #6590

PiperOrigin-RevId: 404007524

3 files changed, 56 insertions, 3 deletions

diff --git a/tools/checklocks/test/BUILD b/tools/checklocks/test/BUILD
index d4d98c256..f2ea6c7c6 100644
--- a/tools/checklocks/test/BUILD
+++ b/tools/checklocks/test/BUILD
@@ -16,6 +16,7 @@ go_library(
         "methods.go",
         "parameters.go",
         "return.go",
+        "rwmutex.go",
         "test.go",
     ],
 )
diff --git a/tools/checklocks/test/basics.go b/tools/checklocks/test/basics.go
index 7a773171f..e941fba5b 100644
--- a/tools/checklocks/test/basics.go
+++ b/tools/checklocks/test/basics.go
@@ -108,14 +108,14 @@ type rwGuardStruct struct {
 
 func testRWValidRead(tc *rwGuardStruct) {
 	tc.rwMu.Lock()
-	tc.guardedField = 1
+	_ = tc.guardedField
 	tc.rwMu.Unlock()
 }
 
 func testRWValidWrite(tc *rwGuardStruct) {
-	tc.rwMu.RLock()
+	tc.rwMu.Lock()
 	tc.guardedField = 2
-	tc.rwMu.RUnlock()
+	tc.rwMu.Unlock()
 }
 
 func testRWInvalidWrite(tc *rwGuardStruct) {
diff --git a/tools/checklocks/test/rwmutex.go b/tools/checklocks/test/rwmutex.go
new file mode 100644
index 000000000..d27ed10e3
--- /dev/null
+++ b/tools/checklocks/test/rwmutex.go
@@ -0,0 +1,52 @@
+// Copyright 2021 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 test
+
+import (
+	"sync"
+)
+
+// oneReadGuardStruct has one read-guarded field.
+type oneReadGuardStruct struct {
+	mu sync.RWMutex
+	// +checklocks:mu
+	guardedField int
+}
+
+func testRWAccessValidRead(tc *oneReadGuardStruct) {
+	tc.mu.Lock()
+	_ = tc.guardedField
+	tc.mu.Unlock()
+	tc.mu.RLock()
+	_ = tc.guardedField
+	tc.mu.RUnlock()
+}
+
+func testRWAccessValidWrite(tc *oneReadGuardStruct) {
+	tc.mu.Lock()
+	tc.guardedField = 1
+	tc.mu.Unlock()
+}
+
+func testRWAccessInvalidWrite(tc *oneReadGuardStruct) {
+	tc.guardedField = 2 // +checklocksfail
+	tc.mu.RLock()
+	tc.guardedField = 2 // +checklocksfail
+	tc.mu.RUnlock()
+}
+
+func testRWAccessInvalidRead(tc *oneReadGuardStruct) {
+	_ = tc.guardedField // +checklocksfail
+}