Merge "atrace: avoid unnecessary writes to trace_clock" into lmp-dev

    return writeStr(k_traceBufferSizePath, str);

}

// Read the trace_clock sysfs file and return true if it matches the requested

// value.  The trace_clock file format is:

// local [global] counter uptime perf

static bool isTraceClock(const char *mode)

{

    int fd = open(k_traceClockPath, O_RDONLY);

    if (fd == -1) {

        fprintf(stderr, "error opening %s: %s (%d)\n", k_traceClockPath,

            strerror(errno), errno);

        return false;

    }

    char buf[4097];

    ssize_t n = read(fd, buf, 4096);

    close(fd);

    if (n == -1) {

        fprintf(stderr, "error reading %s: %s (%d)\n", k_traceClockPath,

            strerror(errno), errno);

        return false;

    }

    buf[n] = '\0';

    char *start = strchr(buf, '[');

    if (start == NULL) {

        return false;

    }

    start++;

    char *end = strchr(start, ']');

    if (end == NULL) {

        return false;

    }

    *end = '\0';

    return strcmp(mode, start) == 0;

}

// Enable or disable the kernel's use of the global clock.  Disabling the global

// clock will result in the kernel using a per-CPU local clock.

// Any write to the trace_clock sysfs file will reset the buffer, so only

// update it if the requested value is not the current value.

static bool setGlobalClockEnable(bool enable)

{

    return writeStr(k_traceClockPath, enable ? "global" : "local");

    const char *clock = enable ? "global" : "local";

    if (isTraceClock(clock)) {

        return true;

    }

    return writeStr(k_traceClockPath, clock);

}

static bool setPrintTgidEnableIfPresent(bool enable)