tracing: Don't print an extra separator of flags

If __print_flags() is used after another __print_*() function, the
temp seq_file buffer will not be empty on entry, and the delimiter will
be printed even though there's just one field. We get something like:

	|S

instead of just:

	S

This is because the length of the temp seq buffer is used to determine
if the delimiter is printed or not. But this algorithm fails when
the seq buffer is not empty on entry, and the delimiter will be printed
because it thinks that a previous field was already printed.

Link: http://lkml.kernel.org/r/1329650167-480655-1-git-send-email-avagin@openvz.org
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 0d6ff3555942968a678dcf6280df8933f58007f5..3efd718984fbbbc00b0a2aef23c408fce271b924 100644 (file)
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -300,7 +300,7 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
        unsigned long mask;
        const char *str;
        const char *ret = p->buffer + p->len;
-       int i;
+       int i, first = 1;
 
        for (i = 0;  flag_array[i].name && flags; i++) {
 
@@ -310,8 +310,10 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
 
                str = flag_array[i].name;
                flags &= ~mask;
-               if (p->len && delim)
+               if (!first && delim)
                        trace_seq_puts(p, delim);
+               else
+                       first = 0;
                trace_seq_puts(p, str);
        }