Merge "master" branch into "db".

[sliver-openvswitch.git] / lib / timeval.c

diff --git a/lib/timeval.c b/lib/timeval.c
index 61f2227..5e42387 100644 (file)
--- a/lib/timeval.c
+++ b/lib/timeval.c
@@ -43,6 +43,8 @@ static struct timeval now;
 /* Time at which to die with SIGALRM (if not TIME_MIN). */
 static time_t deadline = TIME_MIN;
 
+static void set_up_timer(void);
+static void set_up_signal(int flags);
 static void sigalrm_handler(int);
 static void refresh_if_ticked(void);
 static time_t time_add(time_t, time_t);
@@ -50,33 +52,71 @@ static void block_sigalrm(sigset_t *);
 static void unblock_sigalrm(const sigset_t *);
 static void log_poll_interval(long long int last_wakeup,
                               const struct rusage *last_rusage);
-static long long int timeval_to_msec(const struct timeval *);
 
 /* Initializes the timetracking module. */
 void
 time_init(void)
 {
-    struct sigaction sa;
-    struct itimerval itimer;
-
     if (inited) {
         return;
     }
 
+    coverage_init();
+
     inited = true;
     gettimeofday(&now, NULL);
     tick = false;
 
-    /* Set up signal handler. */
+    set_up_signal(SA_RESTART);
+    set_up_timer();
+}
+
+static void
+set_up_signal(int flags)
+{
+    struct sigaction sa;
+
     memset(&sa, 0, sizeof sa);
     sa.sa_handler = sigalrm_handler;
     sigemptyset(&sa.sa_mask);
-    sa.sa_flags = SA_RESTART;
+    sa.sa_flags = flags;
     if (sigaction(SIGALRM, &sa, NULL)) {
         ovs_fatal(errno, "sigaction(SIGALRM) failed");
     }
+}
+
+/* Remove SA_RESTART from the flags for SIGALRM, so that any system call that
+ * is interrupted by the periodic timer interrupt will return EINTR instead of
+ * continuing after the signal handler returns.
+ *
+ * time_disable_restart() and time_enable_restart() may be usefully wrapped
+ * around function calls that might otherwise block forever unless interrupted
+ * by a signal, e.g.:
+ *
+ *   time_disable_restart();
+ *   fcntl(fd, F_SETLKW, &lock);
+ *   time_enable_restart();
+ */
+void
+time_disable_restart(void)
+{
+    set_up_signal(0);
+}
+
+/* Add SA_RESTART to the flags for SIGALRM, so that any system call that
+ * is interrupted by the periodic timer interrupt will continue after the
+ * signal handler returns instead of returning EINTR. */
+void
+time_enable_restart(void)
+{
+    set_up_signal(SA_RESTART);
+}
+
+static void
+set_up_timer(void)
+{
+    struct itimerval itimer;
 
-    /* Set up periodic timer. */
     itimer.it_interval.tv_sec = 0;
     itimer.it_interval.tv_usec = TIME_UPDATE_INTERVAL * 1000;
     itimer.it_value = itimer.it_interval;
@@ -85,6 +125,17 @@ time_init(void)
     }
 }
 
+/* Set up the interval timer, to ensure that time advances even without calling
+ * time_refresh().
+ *
+ * A child created with fork() does not inherit the parent's interval timer, so
+ * this function needs to be called from the child after fork(). */
+void
+time_postfork(void)
+{
+    set_up_timer();
+}
+
 /* Forces a refresh of the current time from the kernel.  It is not usually
  * necessary to call this function, since the time will be refreshed
  * automatically at least every TIME_UPDATE_INTERVAL milliseconds. */
@@ -235,7 +286,7 @@ unblock_sigalrm(const sigset_t *oldsigs)
     }
 }
 
-static long long int
+long long int
 timeval_to_msec(const struct timeval *tv)
 {
     return (long long int) tv->tv_sec * 1000 + tv->tv_usec / 1000;
@@ -292,7 +343,12 @@ log_poll_interval(long long int last_wakeup, const struct rusage *last_rusage)
                       rusage.ru_nvcsw - last_rusage->ru_nvcsw,
                       rusage.ru_nivcsw - last_rusage->ru_nivcsw);
         }
-        coverage_log(VLL_WARN);
+
+        /* Care should be taken in the value chosen for logging.  Depending 
+         * on the configuration, syslog can write changes synchronously, 
+         * which can cause the coverage messages to take longer to log 
+         * than the processing delay that triggered it. */
+        coverage_log(VLL_INFO, true);
     }
 
     /* Update exponentially weighted moving average.  With these parameters, a