commit 0771d8a8b87aa6316e006faaa51207fe8a3beb30
author Steven Moreland <smoreland@google.com> Wed May 09 13:29:14 2018 -0700
committer Steven Moreland <smoreland@google.com> Tue May 15 23:34:50 2018 +0000
tree 6de2fccaa01cdc9639b5ba61aeee5670a34f27b2
parent f3b1f0dac3572e4d79f65fbfbfa3fc8fcf7305f7

getService: re-request HALs after timeout

Lazy HALs are started by hwservicemanager, but there is a possible
race condition:
- HAL is requested to be started and starts
- client queries HAL
- HAL executes query and exits (but init doesn't know this yet)
- client queries HAL
- HAL is requested to be started, but init thinks it is already
    running, so it isn't started again
- init reaps HAL process
- client is waiting for HAL indefinitely

This will only happen in a case where a lazy HAL exits right when it is
requesting.

Fixes: 79427800
Test: $ANDROID_BUILD_TOP/system/tools/hidl/test/run_all_device_tests.sh
Change-Id: I723a182a709f2291debad69fc4141ba9a064645e

transport/ServiceManagement.cpp

diff --git a/transport/ServiceManagement.cpp b/transport/ServiceManagement.cpp
index f11acab..8c46506 100644
--- a/transport/ServiceManagement.cpp
+++ b/transport/ServiceManagement.cpp
@@ -537,7 +537,7 @@
         return Void();
     }
 
-    void wait() {
+    void wait(bool timeout) {
         using std::literals::chrono_literals::operator""s;
 
         if (!mRegisteredForNotifications) {
@@ -548,7 +548,7 @@
         }
 
         std::unique_lock<std::mutex> lock(mMutex);
-        while(true) {
+        do {
             mCondition.wait_for(lock, 1s, [this]{
                 return mRegistered;
             });
@@ -557,9 +557,8 @@
                 break;
             }
 
-            LOG(WARNING) << "Waited one second for " << mInterfaceName << "/" << mInstanceName
-                         << ". Waiting another...";
-        }
+            LOG(WARNING) << "Waited one second for " << mInterfaceName << "/" << mInstanceName;
+        } while (!timeout);
     }
 
     // Be careful when using this; after calling reset(), you must always try to retrieve
@@ -600,7 +599,7 @@
 void waitForHwService(
         const std::string &interface, const std::string &instanceName) {
     sp<Waiter> waiter = new Waiter(interface, instanceName, defaultServiceManager1_1());
-    waiter->wait();
+    waiter->wait(false /* timeout */);
     waiter->done();
 }
 
@@ -710,7 +709,7 @@
 
         if (waiter != nullptr) {
             ALOGI("getService: Trying again for %s/%s...", descriptor.c_str(), instance.c_str());
-            waiter->wait();
+            waiter->wait(true /* timeout */);
         }
     }