Binder API for freeze state change notification.

Bug: 338097747
Change-Id: Iac340abc7a1a0700148cded9adb0451b8a4eae73
Test: atest BinderLibTest

Author: Yu-Ting Tseng

libs/binder/Binder.cpp

@@ -143,6 +143,22 @@ status_t IBinder::getExtension(sp<IBinder>* out) {
     return reply.readNullableStrongBinder(out);
 }
 
+status_t IBinder::addFrozenStateChangeCallback(const wp<FrozenStateChangeCallback>& callback) {
+    BpBinder* proxy = this->remoteBinder();
+    if (proxy != nullptr) {
+        return proxy->addFrozenStateChangeCallback(callback);
+    }
+    return INVALID_OPERATION;
+}
+
+status_t IBinder::removeFrozenStateChangeCallback(const wp<FrozenStateChangeCallback>& callback) {
+    BpBinder* proxy = this->remoteBinder();
+    if (proxy != nullptr) {
+        return proxy->removeFrozenStateChangeCallback(callback);
+    }
+    return INVALID_OPERATION;
+}
+
 status_t IBinder::getDebugPid(pid_t* out) {
     BBinder* local = this->localBinder();
     if (local != nullptr) {

libs/binder/BpBinder.cpp

@@ -557,6 +557,123 @@ void BpBinder::sendObituary()
     }
 }
 
+status_t BpBinder::addFrozenStateChangeCallback(const wp<FrozenStateChangeCallback>& callback) {
+    LOG_ALWAYS_FATAL_IF(isRpcBinder(),
+                        "addFrozenStateChangeCallback() is not supported for RPC Binder.");
+    LOG_ALWAYS_FATAL_IF(!kEnableKernelIpc, "Binder kernel driver disabled at build time");
+    LOG_ALWAYS_FATAL_IF(ProcessState::self()->getThreadPoolMaxTotalThreadCount() == 0,
+                        "addFrozenStateChangeCallback on %s but there are no threads "
+                        "(yet?) listening to incoming transactions. See "
+                        "ProcessState::startThreadPool "
+                        "and ProcessState::setThreadPoolMaxThreadCount. Generally you should "
+                        "setup the binder threadpool before other initialization steps.",
+                        String8(getInterfaceDescriptor()).c_str());
+    LOG_ALWAYS_FATAL_IF(callback == nullptr,
+                        "addFrozenStateChangeCallback(): callback must be non-NULL");
+
+    const sp<FrozenStateChangeCallback> strongCallback = callback.promote();
+    if (strongCallback == nullptr) {
+        return BAD_VALUE;
+    }
+
+    {
+        RpcMutexUniqueLock _l(mLock);
+        if (!mFrozen) {
+            ALOGV("Requesting freeze notification: %p handle %d\n", this, binderHandle());
+            IPCThreadState* self = IPCThreadState::self();
+            status_t status = self->addFrozenStateChangeCallback(binderHandle(), this);
+            if (status != NO_ERROR) {
+                // Avoids logspam if kernel does not support freeze
+                // notification.
+                if (status != INVALID_OPERATION) {
+                    ALOGE("IPCThreadState.addFrozenStateChangeCallback "
+                          "failed with %s. %p handle %d\n",
+                          statusToString(status).c_str(), this, binderHandle());
+                }
+                return status;
+            }
+            mFrozen = std::make_unique<FrozenStateChange>();
+            if (!mFrozen) {
+                std::ignore =
+                        IPCThreadState::self()->removeFrozenStateChangeCallback(binderHandle(),
+                                                                                this);
+                return NO_MEMORY;
+            }
+        }
+        if (mFrozen->initialStateReceived) {
+            strongCallback->onStateChanged(wp<BpBinder>::fromExisting(this),
+                                           mFrozen->isFrozen
+                                                   ? FrozenStateChangeCallback::State::FROZEN
+                                                   : FrozenStateChangeCallback::State::UNFROZEN);
+        }
+        ssize_t res = mFrozen->callbacks.add(callback);
+        if (res < 0) {
+            return res;
+        }
+        return NO_ERROR;
+    }
+}
+
+status_t BpBinder::removeFrozenStateChangeCallback(const wp<FrozenStateChangeCallback>& callback) {
+    LOG_ALWAYS_FATAL_IF(isRpcBinder(),
+                        "removeFrozenStateChangeCallback() is not supported for RPC Binder.");
+    LOG_ALWAYS_FATAL_IF(!kEnableKernelIpc, "Binder kernel driver disabled at build time");
+
+    RpcMutexUniqueLock _l(mLock);
+
+    const size_t N = mFrozen ? mFrozen->callbacks.size() : 0;
+    for (size_t i = 0; i < N; i++) {
+        if (mFrozen->callbacks.itemAt(i) == callback) {
+            mFrozen->callbacks.removeAt(i);
+            if (mFrozen->callbacks.size() == 0) {
+                ALOGV("Clearing freeze notification: %p handle %d\n", this, binderHandle());
+                status_t status =
+                        IPCThreadState::self()->removeFrozenStateChangeCallback(binderHandle(),
+                                                                                this);
+                if (status != NO_ERROR) {
+                    ALOGE("Unexpected error from "
+                          "IPCThreadState.removeFrozenStateChangeCallback: %s. "
+                          "%p handle %d\n",
+                          statusToString(status).c_str(), this, binderHandle());
+                }
+                mFrozen.reset();
+            }
+            return NO_ERROR;
+        }
+    }
+
+    return NAME_NOT_FOUND;
+}
+
+void BpBinder::onFrozenStateChanged(bool isFrozen) {
+    LOG_ALWAYS_FATAL_IF(isRpcBinder(), "onFrozenStateChanged is not supported for RPC Binder.");
+    LOG_ALWAYS_FATAL_IF(!kEnableKernelIpc, "Binder kernel driver disabled at build time");
+
+    ALOGV("Sending frozen state change notification for proxy %p handle %d, isFrozen=%s\n", this,
+          binderHandle(), isFrozen ? "true" : "false");
+
+    RpcMutexUniqueLock _l(mLock);
+    if (!mFrozen) {
+        return;
+    }
+    bool stateChanged = !mFrozen->initialStateReceived || mFrozen->isFrozen != isFrozen;
+    if (stateChanged) {
+        mFrozen->isFrozen = isFrozen;
+        mFrozen->initialStateReceived = true;
+        for (size_t i = 0; i < mFrozen->callbacks.size();) {
+            sp<FrozenStateChangeCallback> callback = mFrozen->callbacks.itemAt(i).promote();
+            if (callback != nullptr) {
+                callback->onStateChanged(wp<BpBinder>::fromExisting(this),
+                                         isFrozen ? FrozenStateChangeCallback::State::FROZEN
+                                                  : FrozenStateChangeCallback::State::UNFROZEN);
+                i++;
+            } else {
+                mFrozen->callbacks.removeItemsAt(i);
+            }
+        }
+    }
+}
+
 void BpBinder::reportOneDeath(const Obituary& obit)
 {
     sp<DeathRecipient> recipient = obit.recipient.promote();
@@ -686,6 +803,10 @@ void BpBinder::onLastStrongRef(const void* /*id*/) {
         if (ipc) ipc->clearDeathNotification(binderHandle(), this);
         mObituaries = nullptr;
     }
+    if (mFrozen != nullptr) {
+        std::ignore = IPCThreadState::self()->removeFrozenStateChangeCallback(binderHandle(), this);
+        mFrozen.reset();
+    }
     mLock.unlock();
 
     if (obits != nullptr) {

libs/binder/IPCThreadState.cpp

@@ -89,26 +89,33 @@ static const char* kReturnStrings[] = {
         "BR_FROZEN_REPLY",
         "BR_ONEWAY_SPAM_SUSPECT",
         "BR_TRANSACTION_PENDING_FROZEN",
+        "BR_FROZEN_BINDER",
+        "BR_CLEAR_FREEZE_NOTIFICATION_DONE",
 };
 
-static const char *kCommandStrings[] = {
-    "BC_TRANSACTION",
-    "BC_REPLY",
-    "BC_ACQUIRE_RESULT",
-    "BC_FREE_BUFFER",
-    "BC_INCREFS",
-    "BC_ACQUIRE",
-    "BC_RELEASE",
-    "BC_DECREFS",
-    "BC_INCREFS_DONE",
-    "BC_ACQUIRE_DONE",
-    "BC_ATTEMPT_ACQUIRE",
-    "BC_REGISTER_LOOPER",
-    "BC_ENTER_LOOPER",
-    "BC_EXIT_LOOPER",
-    "BC_REQUEST_DEATH_NOTIFICATION",
-    "BC_CLEAR_DEATH_NOTIFICATION",
-    "BC_DEAD_BINDER_DONE"
+static const char* kCommandStrings[] = {
+        "BC_TRANSACTION",
+        "BC_REPLY",
+        "BC_ACQUIRE_RESULT",
+        "BC_FREE_BUFFER",
+        "BC_INCREFS",
+        "BC_ACQUIRE",
+        "BC_RELEASE",
+        "BC_DECREFS",
+        "BC_INCREFS_DONE",
+        "BC_ACQUIRE_DONE",
+        "BC_ATTEMPT_ACQUIRE",
+        "BC_REGISTER_LOOPER",
+        "BC_ENTER_LOOPER",
+        "BC_EXIT_LOOPER",
+        "BC_REQUEST_DEATH_NOTIFICATION",
+        "BC_CLEAR_DEATH_NOTIFICATION",
+        "BC_DEAD_BINDER_DONE",
+        "BC_TRANSACTION_SG",
+        "BC_REPLY_SG",
+        "BC_REQUEST_FREEZE_NOTIFICATION",
+        "BC_CLEAR_FREEZE_NOTIFICATION",
+        "BC_FREEZE_NOTIFICATION_DONE",
 };
 
 static const int64_t kWorkSourcePropagatedBitIndex = 32;
@@ -203,6 +210,18 @@ static const void* printReturnCommand(std::ostream& out, const void* _cmd) {
             out << ": death cookie " << (void*)(uint64_t)c;
         } break;
 
+        case BR_FROZEN_BINDER: {
+            const int32_t c = *cmd++;
+            const int32_t h = *cmd++;
+            const int32_t isFrozen = *cmd++;
+            out << ": freeze cookie " << (void*)(uint64_t)c << " isFrozen: " << isFrozen;
+        } break;
+
+        case BR_CLEAR_FREEZE_NOTIFICATION_DONE: {
+            const int32_t c = *cmd++;
+            out << ": freeze cookie " << (void*)(uint64_t)c;
+        } break;
+
         default:
             // no details to show for: BR_OK, BR_DEAD_REPLY,
             // BR_TRANSACTION_COMPLETE, BR_FINISHED
@@ -270,11 +289,23 @@ static const void* printCommand(std::ostream& out, const void* _cmd) {
             out << ": handle=" << h << " (death cookie " << (void*)(uint64_t)c << ")";
         } break;
 
+        case BC_REQUEST_FREEZE_NOTIFICATION:
+        case BC_CLEAR_FREEZE_NOTIFICATION: {
+            const int32_t h = *cmd++;
+            const int32_t c = *cmd++;
+            out << ": handle=" << h << " (freeze cookie " << (void*)(uint64_t)c << ")";
+        } break;
+
         case BC_DEAD_BINDER_DONE: {
             const int32_t c = *cmd++;
             out << ": death cookie " << (void*)(uint64_t)c;
         } break;
 
+        case BC_FREEZE_NOTIFICATION_DONE: {
+            const int32_t c = *cmd++;
+            out << ": freeze cookie " << (void*)(uint64_t)c;
+        } break;
+
         default:
             // no details to show for: BC_REGISTER_LOOPER, BC_ENTER_LOOPER,
             // BC_EXIT_LOOPER
@@ -951,6 +982,33 @@ status_t IPCThreadState::clearDeathNotification(int32_t handle, BpBinder* proxy)
     return NO_ERROR;
 }
 
+status_t IPCThreadState::addFrozenStateChangeCallback(int32_t handle, BpBinder* proxy) {
+    static bool isSupported =
+            ProcessState::isDriverFeatureEnabled(ProcessState::DriverFeature::FREEZE_NOTIFICATION);
+    if (!isSupported) {
+        return INVALID_OPERATION;
+    }
+    proxy->getWeakRefs()->incWeak(proxy);
+    mOut.writeInt32(BC_REQUEST_FREEZE_NOTIFICATION);
+    mOut.writeInt32((int32_t)handle);
+    mOut.writePointer((uintptr_t)proxy);
+    flushCommands();
+    return NO_ERROR;
+}
+
+status_t IPCThreadState::removeFrozenStateChangeCallback(int32_t handle, BpBinder* proxy) {
+    static bool isSupported =
+            ProcessState::isDriverFeatureEnabled(ProcessState::DriverFeature::FREEZE_NOTIFICATION);
+    if (!isSupported) {
+        return INVALID_OPERATION;
+    }
+    mOut.writeInt32(BC_CLEAR_FREEZE_NOTIFICATION);
+    mOut.writeInt32((int32_t)handle);
+    mOut.writePointer((uintptr_t)proxy);
+    flushCommands();
+    return NO_ERROR;
+}
+
 IPCThreadState::IPCThreadState()
       : mProcess(ProcessState::self()),
         mServingStackPointer(nullptr),
@@ -1485,6 +1543,26 @@ status_t IPCThreadState::executeCommand(int32_t cmd)
             proxy->getWeakRefs()->decWeak(proxy);
         } break;
 
+        case BR_FROZEN_BINDER: {
+            const struct binder_frozen_state_info* data =
+                    reinterpret_cast<const struct binder_frozen_state_info*>(
+                            mIn.readInplace(sizeof(struct binder_frozen_state_info)));
+            if (data == nullptr) {
+                result = UNKNOWN_ERROR;
+                break;
+            }
+            BpBinder* proxy = (BpBinder*)data->cookie;
+            bool isFrozen = mIn.readInt32() > 0;
+            proxy->getPrivateAccessor().onFrozenStateChanged(data->is_frozen);
+            mOut.writeInt32(BC_FREEZE_NOTIFICATION_DONE);
+            mOut.writePointer(data->cookie);
+        } break;
+
+        case BR_CLEAR_FREEZE_NOTIFICATION_DONE: {
+            BpBinder* proxy = (BpBinder*)mIn.readPointer();
+            proxy->getWeakRefs()->decWeak(proxy);
+        } break;
+
     case BR_FINISHED:
         result = TIMED_OUT;
         break;

libs/binder/ProcessState.cpp

@@ -57,6 +57,25 @@ const char* kDefaultDriver = "/dev/binder";
 
 // -------------------------------------------------------------------------
 
+namespace {
+bool readDriverFeatureFile(const char* filename) {
+    int fd = open(filename, O_RDONLY | O_CLOEXEC);
+    char on;
+    if (fd == -1) {
+        ALOGE_IF(errno != ENOENT, "%s: cannot open %s: %s", __func__, filename, strerror(errno));
+        return false;
+    }
+    if (read(fd, &on, sizeof(on)) == -1) {
+        ALOGE("%s: error reading to %s: %s", __func__, filename, strerror(errno));
+        close(fd);
+        return false;
+    }
+    close(fd);
+    return on == '1';
+}
+
+} // namespace
+
 namespace android {
 
 using namespace android::binder::impl;
@@ -472,27 +491,20 @@ bool ProcessState::isThreadPoolStarted() const {
 
 #define DRIVER_FEATURES_PATH "/dev/binderfs/features/"
 bool ProcessState::isDriverFeatureEnabled(const DriverFeature feature) {
-    static const char* const names[] = {
-        [static_cast<int>(DriverFeature::ONEWAY_SPAM_DETECTION)] =
-            DRIVER_FEATURES_PATH "oneway_spam_detection",
-        [static_cast<int>(DriverFeature::EXTENDED_ERROR)] =
-            DRIVER_FEATURES_PATH "extended_error",
-    };
-    int fd = open(names[static_cast<int>(feature)], O_RDONLY | O_CLOEXEC);
-    char on;
-    if (fd == -1) {
-        ALOGE_IF(errno != ENOENT, "%s: cannot open %s: %s", __func__,
-                 names[static_cast<int>(feature)], strerror(errno));
-        return false;
+    // Use static variable to cache the results.
+    if (feature == DriverFeature::ONEWAY_SPAM_DETECTION) {
+        static bool enabled = readDriverFeatureFile(DRIVER_FEATURES_PATH "oneway_spam_detection");
+        return enabled;
     }
-    if (read(fd, &on, sizeof(on)) == -1) {
-        ALOGE("%s: error reading to %s: %s", __func__,
-                 names[static_cast<int>(feature)], strerror(errno));
-        close(fd);
-        return false;
+    if (feature == DriverFeature::EXTENDED_ERROR) {
+        static bool enabled = readDriverFeatureFile(DRIVER_FEATURES_PATH "extended_error");
+        return enabled;
     }
-    close(fd);
-    return on == '1';
+    if (feature == DriverFeature::FREEZE_NOTIFICATION) {
+        static bool enabled = readDriverFeatureFile(DRIVER_FEATURES_PATH "freeze_notification");
+        return enabled;
+    }
+    return false;
 }
 
 status_t ProcessState::enableOnewaySpamDetection(bool enable) {