am 1685b099: am 8836031b: Merge "adb: win32: fix shutdown deadlock"

static int  _winsock_init;

static void

_cleanup_winsock( void )

{

    // TODO: WSAStartup() might be called multiple times and this won't properly

    // cleanup the right number of times. Plus, WSACleanup() probably doesn't

    // make sense since it might interrupt other threads using Winsock (since

    // our various threads are not explicitly cleanly shutdown at process exit).

    WSACleanup();

}

static void

_init_winsock( void )

{

    // TODO: Multiple threads calling this may potentially cause multiple calls

    // to WSAStartup() and multiple atexit() calls.

    // to WSAStartup() which offers no real benefit.

    if (!_winsock_init) {

        WSADATA  wsaData;

        int      rc = WSAStartup( MAKEWORD(2,2), &wsaData);

            fatal( "adb: could not initialize Winsock: %s",

                   SystemErrorCodeToString( rc ).c_str());

        }

        atexit( _cleanup_winsock );

        _winsock_init = 1;

        // Note that we do not call atexit() to register WSACleanup to be called

        // at normal process termination because:

        // 1) When exit() is called, there are still threads actively using

        //    Winsock because we don't cleanly shutdown all threads, so it

        //    doesn't make sense to call WSACleanup() and may cause problems

        //    with those threads.

        // 2) A deadlock can occur when exit() holds a C Runtime lock, then it

        //    calls WSACleanup() which tries to unload a DLL, which tries to

        //    grab the LoaderLock. This conflicts with the device_poll_thread

        //    which holds the LoaderLock because AdbWinApi.dll calls

        //    setupapi.dll which tries to load wintrust.dll which tries to load

        //    crypt32.dll which calls atexit() which tries to acquire the C

        //    Runtime lock that the other thread holds.

    }

}