From db1597a98958b78dc0d8eced19ae1406382b70d6 Mon Sep 17 00:00:00 2001 From: Johannes Carlsson Date: Thu, 17 Feb 2011 14:06:53 +0100 Subject: [PATCH] Fix shutdown sequence to avoid SIGSEGV when running am command When the app_process is shutting down the main thread will close the binder fd while pool threads are executing an ioctl (in IPCThreadState::stopProcess called by AppRuntime::onStarted in app_main.c). The binder driver will then return all pending calls in ioctl without any error and with a command. One of the threads gets a BR_SPAWN_LOOPER which will create a new thread (the other thread gets a BR_NOOP). This new thread then calls vm->AttachCurrentThread. Usually this results in a log entry with "AndroidRuntime: NOTE: attach of thread 'Binder Thread #3' failed", but sometimes it also causes a SIGSEGV. This depends on the timing between the new thread an the main thread that calls DestroyJavaVM (in AndroidRuntime::start). If IPCThreadState.cpp is compiled with "#define LOG_NDEBUG 0" the pool thread will loop and hit the ALOG_ASSERT(mProcess->mDriverFD >= 0) in IPCThreadState::talkWithDriver. Crashes like this has been seen when running the am command and other commands that use the app_process. This fix makes sure that any command that is received when the driver fd is closed are ignored and IPCThreadState::talkWithDriver instead returns an error which will cause the pool thread to exit and detach itself from the vm. A check to avoid calling ioctl to a fd with -1 was also added in IPCThreadState::threadDestructor. Another solution might be to change the binder driver so that it returns an error when the fd is closed (or atleast not a BR_SPAWN_LOOPER command). It might also be possible to call exit(0) which is done when System.exit(0) is called from java. Change-Id: I3d1f0ff64896c44be2a5994b3a90f7a06d27f429 --- libs/binder/IPCThreadState.cpp | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/libs/binder/IPCThreadState.cpp b/libs/binder/IPCThreadState.cpp index 7a3a3b9f5..7e416b9d5 100644 --- a/libs/binder/IPCThreadState.cpp +++ b/libs/binder/IPCThreadState.cpp @@ -758,7 +758,9 @@ finish: status_t IPCThreadState::talkWithDriver(bool doReceive) { - ALOG_ASSERT(mProcess->mDriverFD >= 0, "Binder driver is not opened"); + if (mProcess->mDriverFD <= 0) { + return -EBADF; + } binder_write_read bwr; @@ -814,6 +816,9 @@ status_t IPCThreadState::talkWithDriver(bool doReceive) #else err = INVALID_OPERATION; #endif + if (mProcess->mDriverFD <= 0) { + err = -EBADF; + } IF_LOG_COMMANDS() { alog << "Finished read/write, write size = " << mOut.dataSize() << endl; } @@ -1106,7 +1111,9 @@ void IPCThreadState::threadDestructor(void *st) if (self) { self->flushCommands(); #if defined(HAVE_ANDROID_OS) - ioctl(self->mProcess->mDriverFD, BINDER_THREAD_EXIT, 0); + if (self->mProcess->mDriverFD > 0) { + ioctl(self->mProcess->mDriverFD, BINDER_THREAD_EXIT, 0); + } #endif delete self; }