frameworks/base: acquire lock on am only when needed

     * to append various headers to the dropbox log text.

     */

    private void appendDropBoxProcessHeaders(ProcessRecord process, StringBuilder sb) {

        // Watchdog thread ends up invoking this function (with

        // a null ProcessRecord) to add the stack file to dropbox.

        // Do not acquire a lock on this (am) in such cases, as it

        // could cause a potential deadlock, if and when watchdog

        // is invoked due to unavailability of lock on am and it

        // would prevent watchdog from killing system_server.

        if (process == null) {

            sb.append("Process: system_server\n");

            return;

        }

        // Note: ProcessRecord 'process' is guarded by the service

        // instance.  (notably process.pkgList, which could otherwise change

        // concurrently during execution of this method)

        synchronized (this) {

            if (process == null || process.pid == MY_PID) {

            if (process.pid == MY_PID) {

                sb.append("Process: system_server\n");

            } else {

                sb.append("Process: ").append(process.processName).append("\n");

            }

            if (process == null) {

                return;

            }

            int flags = process.info.flags;

            IPackageManager pm = AppGlobals.getPackageManager();

            sb.append("Flags: 0x").append(Integer.toString(flags, 16)).append("\n");