Balance the posix clock open function with a close method.

The one user of the function, posix_clock_open(), simply open codes
the closing call to phc_close().  This patch provides a method to
balance closing and opening of a posix clock.  In addition, the
phc_ctl program never explicitly closed the opened clock, and so this
patch adds the missing call.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>

phc2sys.c

@@ -341,7 +341,7 @@ static void clock_reinit(struct node *node, struct clock *clock, int new_state)
 			if (clkid == CLOCK_INVALID)
 				return;
 
-			phc_close(clock->clkid);
+			posix_clock_close(clock->clkid);
 			clock->clkid = clkid;
 			clock->phc_index = phc_index;
 

phc_ctl.c

@@ -531,6 +531,7 @@ int main(int argc, char *argv[])
 
 	/* pass the remaining arguments to the run_cmds loop */
 	result = run_cmds(clkid, cmdc, cmdv);
+	posix_clock_close(clkid);
 	if (result < -1) {
 		/* show usage when command fails */
 		usage(progname);

util.c

@@ -190,6 +190,14 @@ char *portaddr2str(struct PortAddress *addr)
 	return buf;
 }
 
+void posix_clock_close(clockid_t clock)
+{
+	if (clock == CLOCK_REALTIME) {
+		return;
+	}
+	phc_close(clock);
+}
+
 clockid_t posix_clock_open(const char *device, int *phc_index)
 {
 	struct sk_ts_info ts_info;

util.h

@@ -110,6 +110,12 @@ char *pid2str(struct PortIdentity *id);
 
 char *portaddr2str(struct PortAddress *addr);
 
+/**
+ * Closes a dynamic posix clock.
+ * @param clock  A clock ID obtained via posix_clock_close().
+ */
+void posix_clock_close(clockid_t clock);
+
 /**
  * Opens a dynamic posix clock by name.
  * @param device     The PHC character device or network interface to open.