[Xen-devel] [PATCH] replacing gettimeofday with clock_gettime in hw/serial

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

This patch substitutes gettimeofday with clock_gettime in hw/serial.c.

The use of gettimeofday in serial is not nearly as dangerous as in
xenconsoled, but it is still worth fixing it.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

---

diff --git a/hw/serial.c b/hw/serial.c
index d49b5de..6ae3b20 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -155,8 +155,8 @@ struct SerialState {
    doesn't kill dom0.  Simple token bucket.  If we get some actual
    data from the user, instantly refil the bucket. */
 
-/* How long it takes to generate a token, in microseconds. */
-#define TOKEN_PERIOD 1000
+/* How long it takes to generate a token, in nanoseconds. */
+#define TOKEN_PERIOD 1000000
 /* Maximum and initial size of token bucket */
 #define TOKENS_MAX 100000
 
@@ -279,47 +279,47 @@ static void serial_update_parameters(SerialState *s)
 
 static void serial_get_token(void)
 {
-    static struct timeval last_refil_time;
+    static struct timespec last_refil_time;
     static int started;
 
     assert(tokens_avail >= 0);
     if (!tokens_avail) {
-       struct timeval delta, now;
-       int generated;
+       struct timespec delta, now;
+       long generated;
 
        if (!started) {
-           gettimeofday(&last_refil_time, NULL);
+           clock_gettime(CLOCK_MONOTONIC, &last_refil_time);
            tokens_avail = TOKENS_MAX;
            started = 1;
            return;
        }
     retry:
-       gettimeofday(&now, NULL);
+       clock_gettime(CLOCK_MONOTONIC, &now);
        delta.tv_sec = now.tv_sec - last_refil_time.tv_sec;
-       delta.tv_usec = now.tv_usec - last_refil_time.tv_usec;
-       if (delta.tv_usec < 0) {
-           delta.tv_usec += 1000000;
+       delta.tv_nsec = now.tv_nsec - last_refil_time.tv_nsec;
+       if (delta.tv_nsec < 0) {
+           delta.tv_nsec += 1000000000;
            delta.tv_sec--;
        }
-       assert(delta.tv_usec >= 0 && delta.tv_sec >= 0);
-       if (delta.tv_usec < TOKEN_PERIOD) {
+       assert(delta.tv_nsec >= 0 && delta.tv_sec >= 0);
+       if (delta.tv_nsec < TOKEN_PERIOD) {
            struct timespec ts;
            /* Wait until at least one token is available. */
-           ts.tv_sec = TOKEN_PERIOD / 1000000;
-           ts.tv_nsec = (TOKEN_PERIOD % 1000000) * 1000;
+           ts.tv_sec = TOKEN_PERIOD / 1000000000;
+           ts.tv_nsec = TOKEN_PERIOD % 1000000000;
            while (nanosleep(&ts, &ts) < 0 && errno == EINTR)
                ;
            goto retry;
        }
-       generated = (delta.tv_sec * 1000000) / TOKEN_PERIOD;
+       generated = (delta.tv_sec * 1000000000) / TOKEN_PERIOD;
        generated +=
-           ((delta.tv_sec * 1000000) % TOKEN_PERIOD + delta.tv_usec) / 
TOKEN_PERIOD;
+           ((delta.tv_sec * 1000000000) % TOKEN_PERIOD + delta.tv_nsec) / 
TOKEN_PERIOD;
        assert(generated > 0);
 
-       last_refil_time.tv_usec += (generated * TOKEN_PERIOD) % 1000000;
-       last_refil_time.tv_sec  += last_refil_time.tv_usec / 1000000;
-       last_refil_time.tv_usec %= 1000000;
-       last_refil_time.tv_sec  += (generated * TOKEN_PERIOD) / 1000000;
+       last_refil_time.tv_nsec += (generated * TOKEN_PERIOD) % 1000000000;
+       last_refil_time.tv_sec  += last_refil_time.tv_nsec / 1000000000;
+       last_refil_time.tv_nsec %= 1000000000;
+        last_refil_time.tv_sec  += (generated * TOKEN_PERIOD) / 1000000000;
        if (generated > TOKENS_MAX)
            generated = TOKENS_MAX;
        tokens_avail = generated;

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