diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index fa7ac41..d94862a 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -751,12 +751,12 @@
 
     result.append("Notification Clients:\n");
     result.append("   pid    uid  name\n");
-    for (size_t i = 0; i < mNotificationClients.size(); ++i) {
-        const pid_t pid = mNotificationClients[i]->getPid();
-        const uid_t uid = mNotificationClients[i]->getUid();
+    for (const auto& [ _, client ] : mNotificationClients) {
+        const uid_t uid = client->getUid();
         const std::shared_ptr<const mediautils::UidInfo::Info> info =
                 mediautils::UidInfo::getInfo(uid);
-        result.appendFormat("%6d %6u  %s\n", pid, uid, info->package.c_str());
+        result.appendFormat("%6d %6u  %s\n",
+                client->getPid(), uid, info->package.c_str());
     }
 
     result.append("Global session refs:\n");
@@ -2164,24 +2164,22 @@
 
 void AudioFlinger::registerClient(const sp<media::IAudioFlingerClient>& client)
 {
-    audio_utils::lock_guard _l(mutex());
     if (client == 0) {
         return;
     }
-    pid_t pid = IPCThreadState::self()->getCallingPid();
+    const pid_t pid = IPCThreadState::self()->getCallingPid();
     const uid_t uid = IPCThreadState::self()->getCallingUid();
+
+    audio_utils::lock_guard _l(mutex());
     {
         audio_utils::lock_guard _cl(clientMutex());
-        if (mNotificationClients.indexOfKey(pid) < 0) {
-            sp<NotificationClient> notificationClient = new NotificationClient(this,
-                                                                                client,
-                                                                                pid,
-                                                                                uid);
+        if (mNotificationClients.count(pid) == 0) {
+            auto notificationClient = sp<NotificationClient>::make(
+                    this, client, pid, uid);
             ALOGV("registerClient() client %p, pid %d, uid %u",
                     notificationClient.get(), pid, uid);
 
-            mNotificationClients.add(pid, notificationClient);
-
+            mNotificationClients[pid] = notificationClient;
             sp<IBinder> binder = IInterface::asBinder(client);
             binder->linkToDeath(notificationClient);
         }
@@ -2208,7 +2206,7 @@
         audio_utils::lock_guard _l(mutex());
         {
             audio_utils::lock_guard _cl(clientMutex());
-            mNotificationClients.removeItem(pid);
+            mNotificationClients.erase(pid);
         }
 
         ALOGV("%d died, releasing its sessions", pid);
@@ -2249,11 +2247,13 @@
             legacy2aidl_AudioIoDescriptor_AudioIoDescriptor(ioDesc));
 
     audio_utils::lock_guard _l(clientMutex());
-    size_t size = mNotificationClients.size();
-    for (size_t i = 0; i < size; i++) {
-        if ((pid == 0) || (mNotificationClients.keyAt(i) == pid)) {
-            mNotificationClients.valueAt(i)->audioFlingerClient()->ioConfigChanged(eventAidl,
-                                                                                   descAidl);
+    if (pid != 0) {
+        if (auto it = mNotificationClients.find(pid); it != mNotificationClients.end()) {
+            it->second->audioFlingerClient()->ioConfigChanged(eventAidl, descAidl);
+        }
+    } else {
+        for (const auto& [ client_pid, client] : mNotificationClients) {
+            client->audioFlingerClient()->ioConfigChanged(eventAidl, descAidl);
         }
     }
 }
@@ -2267,9 +2267,8 @@
 
     audio_utils::lock_guard _l(clientMutex());
     size_t size = mNotificationClients.size();
-    for (size_t i = 0; i < size; i++) {
-        mNotificationClients.valueAt(i)->audioFlingerClient()
-                ->onSupportedLatencyModesChanged(outputAidl, modesAidl);
+    for (const auto& [_, client] : mNotificationClients) {
+        client->audioFlingerClient()->onSupportedLatencyModesChanged(outputAidl, modesAidl);
     }
 }
 
@@ -2337,7 +2336,7 @@
 
 void AudioFlinger::NotificationClient::binderDied(const wp<IBinder>& who __unused)
 {
-    sp<NotificationClient> keep(this);
+    const auto keep = sp<NotificationClient>::fromExisting(this);
     mAudioFlinger->removeNotificationClient(mPid);
 }
 
@@ -3604,7 +3603,7 @@
         // is likely proxied by mediaserver (e.g CameraService) and releaseAudioSessionId() can be
         // called from a different pid leaving a stale session reference.  Also we don't know how
         // to clear this reference if the client process dies.
-        if (mNotificationClients.indexOfKey(caller) < 0) {
+        if (mNotificationClients.count(caller) == 0) {
             ALOGW("acquireAudioSessionId() unknown client %d for session %d", caller, audioSession);
             return;
         }