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-rw-r--r--cmds/servicemanager/ServiceManager.cpp88
-rw-r--r--cmds/servicemanager/ServiceManager.h6
2 files changed, 57 insertions, 37 deletions
diff --git a/cmds/servicemanager/ServiceManager.cpp b/cmds/servicemanager/ServiceManager.cpp
index 695faf8a78..5ded165888 100644
--- a/cmds/servicemanager/ServiceManager.cpp
+++ b/cmds/servicemanager/ServiceManager.cpp
@@ -222,6 +222,10 @@ static bool meetsDeclarationRequirements(const sp<IBinder>& binder, const std::s
}
#endif // !VENDORSERVICEMANAGER
+ServiceManager::Service::~Service() {
+ CHECK(!hasClients) << "BAD STATE: service unregistered when we know we have clients";
+}
+
ServiceManager::ServiceManager(std::unique_ptr<Access>&& access) : mAccess(std::move(access)) {
// TODO(b/151696835): reenable performance hack when we solve bug, since with
// this hack and other fixes, it is unlikely we will see even an ephemeral
@@ -293,8 +297,13 @@ sp<IBinder> ServiceManager::tryGetService(const std::string& name, bool startIfN
}
if (out) {
- // Setting this guarantee each time we hand out a binder ensures that the client-checking
- // loop knows about the event even if the client immediately drops the service
+ // Force onClients to get sent, and then make sure the timerfd won't clear it
+ // by setting guaranteeClient again. This logic could be simplified by using
+ // a time-based guarantee. However, forcing onClients(true) to get sent
+ // right here is always going to be important for processes serving multiple
+ // lazy interfaces.
+ service->guaranteeClient = true;
+ CHECK(handleServiceClientCallback(2 /* sm + transaction */, name, false));
service->guaranteeClient = true;
}
@@ -384,8 +393,13 @@ Status ServiceManager::addService(const std::string& name, const sp<IBinder>& bi
};
if (auto it = mNameToRegistrationCallback.find(name); it != mNameToRegistrationCallback.end()) {
+ // See also getService - handles case where client never gets the service,
+ // we want the service to quit.
+ mNameToService[name].guaranteeClient = true;
+ CHECK(handleServiceClientCallback(2 /* sm + transaction */, name, false));
+ mNameToService[name].guaranteeClient = true;
+
for (const sp<IServiceCallback>& cb : it->second) {
- mNameToService[name].guaranteeClient = true;
// permission checked in registerForNotifications
cb->onRegistration(name, binder);
}
@@ -696,28 +710,28 @@ ssize_t ServiceManager::Service::getNodeStrongRefCount() {
void ServiceManager::handleClientCallbacks() {
for (const auto& [name, service] : mNameToService) {
- handleServiceClientCallback(name, true);
+ handleServiceClientCallback(1 /* sm has one refcount */, name, true);
}
}
-ssize_t ServiceManager::handleServiceClientCallback(const std::string& serviceName,
- bool isCalledOnInterval) {
+bool ServiceManager::handleServiceClientCallback(size_t knownClients,
+ const std::string& serviceName,
+ bool isCalledOnInterval) {
auto serviceIt = mNameToService.find(serviceName);
if (serviceIt == mNameToService.end() || mNameToClientCallback.count(serviceName) < 1) {
- return -1;
+ return true; // return we do have clients a.k.a. DON'T DO ANYTHING
}
Service& service = serviceIt->second;
ssize_t count = service.getNodeStrongRefCount();
- // binder driver doesn't support this feature
- if (count == -1) return count;
+ // binder driver doesn't support this feature, consider we have clients
+ if (count == -1) return true;
- bool hasClients = count > 1; // this process holds a strong count
+ bool hasKernelReportedClients = static_cast<size_t>(count) > knownClients;
if (service.guaranteeClient) {
- // we have no record of this client
- if (!service.hasClients && !hasClients) {
+ if (!service.hasClients && !hasKernelReportedClients) {
sendClientCallbackNotifications(serviceName, true,
"service is guaranteed to be in use");
}
@@ -726,21 +740,23 @@ ssize_t ServiceManager::handleServiceClientCallback(const std::string& serviceNa
service.guaranteeClient = false;
}
- // only send notifications if this was called via the interval checking workflow
- if (isCalledOnInterval) {
- if (hasClients && !service.hasClients) {
- // client was retrieved in some other way
- sendClientCallbackNotifications(serviceName, true, "we now have a record of a client");
- }
+ // Regardless of this situation, we want to give this notification as soon as possible.
+ // This way, we have a chance of preventing further thrashing.
+ if (hasKernelReportedClients && !service.hasClients) {
+ sendClientCallbackNotifications(serviceName, true, "we now have a record of a client");
+ }
- // there are no more clients, but the callback has not been called yet
- if (!hasClients && service.hasClients) {
+ // But limit rate of shutting down service.
+ if (isCalledOnInterval) {
+ if (!hasKernelReportedClients && service.hasClients) {
sendClientCallbackNotifications(serviceName, false,
"we now have no record of a client");
}
}
- return count;
+ // May be different than 'hasKernelReportedClients'. We intentionally delay
+ // information about clients going away to reduce thrashing.
+ return service.hasClients;
}
void ServiceManager::sendClientCallbackNotifications(const std::string& serviceName,
@@ -753,13 +769,10 @@ void ServiceManager::sendClientCallbackNotifications(const std::string& serviceN
}
Service& service = serviceIt->second;
- CHECK(hasClients != service.hasClients)
- << "Record shows: " << service.hasClients
- << " so we can't tell clients again that we have client: " << hasClients
- << " when: " << context;
+ CHECK_NE(hasClients, service.hasClients) << context;
- ALOGI("Notifying %s they %s have clients when %s", serviceName.c_str(),
- hasClients ? "do" : "don't", context);
+ ALOGI("Notifying %s they %s (previously: %s) have clients when %s", serviceName.c_str(),
+ hasClients ? "do" : "don't", service.hasClients ? "do" : "don't", context);
auto ccIt = mNameToClientCallback.find(serviceName);
CHECK(ccIt != mNameToClientCallback.end())
@@ -803,26 +816,29 @@ Status ServiceManager::tryUnregisterService(const std::string& name, const sp<IB
return Status::fromExceptionCode(Status::EX_ILLEGAL_STATE);
}
+ // important because we don't have timer-based guarantees, we don't want to clear
+ // this
if (serviceIt->second.guaranteeClient) {
ALOGI("Tried to unregister %s, but there is about to be a client.", name.c_str());
return Status::fromExceptionCode(Status::EX_ILLEGAL_STATE);
}
- int clients = handleServiceClientCallback(name, false);
-
- // clients < 0: feature not implemented or other error. Assume clients.
- // Otherwise:
// - kernel driver will hold onto one refcount (during this transaction)
// - servicemanager has a refcount (guaranteed by this transaction)
- // So, if clients > 2, then at least one other service on the system must hold a refcount.
- if (clients < 0 || clients > 2) {
- // client callbacks are either disabled or there are other clients
- ALOGI("Tried to unregister %s, but there are clients: %d", name.c_str(), clients);
- // Set this flag to ensure the clients are acknowledged in the next callback
+ constexpr size_t kKnownClients = 2;
+
+ if (handleServiceClientCallback(kKnownClients, name, false)) {
+ ALOGI("Tried to unregister %s, but there are clients.", name.c_str());
+
+ // Since we had a failed registration attempt, and the HIDL implementation of
+ // delaying service shutdown for multiple periods wasn't ported here... this may
+ // help reduce thrashing, but we should be able to remove it.
serviceIt->second.guaranteeClient = true;
+
return Status::fromExceptionCode(Status::EX_ILLEGAL_STATE);
}
+ ALOGI("Unregistering %s", name.c_str());
mNameToService.erase(name);
return Status::ok();
diff --git a/cmds/servicemanager/ServiceManager.h b/cmds/servicemanager/ServiceManager.h
index f9d4f8fd90..3aa6731eb3 100644
--- a/cmds/servicemanager/ServiceManager.h
+++ b/cmds/servicemanager/ServiceManager.h
@@ -80,6 +80,8 @@ private:
// the number of clients of the service, including servicemanager itself
ssize_t getNodeStrongRefCount();
+
+ ~Service();
};
using ServiceCallbackMap = std::map<std::string, std::vector<sp<IServiceCallback>>>;
@@ -91,7 +93,9 @@ private:
void removeRegistrationCallback(const wp<IBinder>& who,
ServiceCallbackMap::iterator* it,
bool* found);
- ssize_t handleServiceClientCallback(const std::string& serviceName, bool isCalledOnInterval);
+ // returns whether there are known clients in addition to the count provided
+ bool handleServiceClientCallback(size_t knownClients, const std::string& serviceName,
+ bool isCalledOnInterval);
// Also updates mHasClients (of what the last callback was)
void sendClientCallbackNotifications(const std::string& serviceName, bool hasClients,
const char* context);
generated by cgit v1.2.3-59-g8ed1b (git 2.39.0) at 2025-10-20 04:39:01 +0000