adjust the sequence of lock

Signed-off-by: Xintao <[email protected]>

src/lib.rs

@@ -599,20 +599,19 @@ pub fn new_fail_group() -> FailPointRegistry {
 impl FailPointRegistry {
     /// Register the current thread to this failpoints registry.
     pub fn register_current(&self) {
+        let mut registry_group = REGISTRY_GROUP.write().unwrap();
         let mut registry = self.registry.write().unwrap();
         let id = thread::current().id();
-        REGISTRY_GROUP
-            .write()
-            .unwrap()
-            .insert(id, self.registry.clone());
+        registry_group.insert(id, self.registry.clone());
         registry.threads.insert(id);
     }
 
     /// Deregister the current thread to this failpoints registry.
     pub fn deregister_current(&self) {
+        let mut registry_group = REGISTRY_GROUP.write().unwrap();
         let mut registry = self.registry.write().unwrap();
         let id = thread::current().id();
-        REGISTRY_GROUP.write().unwrap().remove(&id);
+        registry_group.remove(&id);
         registry.threads.remove(&id);
     }
 
@@ -687,12 +686,12 @@ pub fn teardown() {
 
 /// Clean all registered fail points.
 fn cleanup(registry: &mut std::sync::RwLockWriteGuard<Registry>) {
+    let mut group = REGISTRY_GROUP.write().unwrap();
     for p in registry.failpoints.values() {
         // wake up all pause failpoint.
         p.set_actions("", vec![]);
     }
     registry.failpoints.clear();
-    let mut group = REGISTRY_GROUP.write().unwrap();
     for id in registry.threads.iter() {
         group.remove(id);
     }

tests/tests.rs

@@ -297,3 +297,26 @@ fn test_multiple_threads_cleanup() {
     );
     t.join().unwrap();
 }
+
+#[test]
+fn test_deadlock() {
+    let group = fail::new_fail_group();
+
+    fail::cfg("point", "return").unwrap();
+    let f = || {
+        fail_point!("point", |_| 1);
+        0
+    };
+
+    let thread = thread::spawn(move || {
+        for _ in 0..5000000 {
+            group.register_current()
+        }
+    });
+
+    for _ in 0..5000000 {
+        f();
+    }
+
+    thread.join().unwrap();
+}