ktest.pl: Just open up the log file once

Currently, every write to the log file is done by opening the file, writing
to it, then closing the file. This rather expensive. Just open it at the
beginning and close it at the end.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/testing/ktest/ktest.pl

@@ -509,9 +509,7 @@ EOF
 
 sub _logit {
     if (defined($opt{"LOG_FILE"})) {
-	open(OUT, ">> $opt{LOG_FILE}") or die "Can't write to $opt{LOG_FILE}";
-	print OUT @_;
-	close(OUT);
+	print LOG @_;
     }
 }
 
@@ -1780,8 +1778,6 @@ sub run_command {
 	(fail "unable to exec $command" and return 0);
 
     if (defined($opt{"LOG_FILE"})) {
-	open(LOG, ">>$opt{LOG_FILE}") or
-	    dodie "failed to write to log";
 	$dolog = 1;
     }
 
@@ -1829,7 +1825,6 @@ sub run_command {
     }
 
     close(CMD);
-    close(LOG) if ($dolog);
     close(RD)  if ($dord);
 
     $end_time = time;
@@ -4091,8 +4086,11 @@ if ($#new_configs >= 0) {
     }
 }
 
-if ($opt{"CLEAR_LOG"} && defined($opt{"LOG_FILE"})) {
-    unlink $opt{"LOG_FILE"};
+if (defined($opt{"LOG_FILE"})) {
+    if ($opt{"CLEAR_LOG"}) {
+	unlink $opt{"LOG_FILE"};
+    }
+    open(LOG, ">> $opt{LOG_FILE}") or die "Can't write to $opt{LOG_FILE}";
 }
 
 doprint "\n\nSTARTING AUTOMATED TESTS\n\n";
@@ -4453,14 +4451,16 @@ if ($opt{"POWEROFF_ON_SUCCESS"}) {
 }
 
 
-if (defined($opt{"LOG_FILE"})) {
-    print "\n See $opt{LOG_FILE} for the record of results.\n";
-}
-
 doprint "\n    $successes of $opt{NUM_TESTS} tests were successful\n\n";
 
 if ($email_when_finished) {
     send_email("KTEST: Your test has finished!",
             "$successes of $opt{NUM_TESTS} tests started at $script_start_time were successful!");
 }
+
+if (defined($opt{"LOG_FILE"})) {
+    print "\n See $opt{LOG_FILE} for the record of results.\n\n";
+    close LOG;
+}
+
 exit 0;