perf probe: Fix to show which probe point is not found

Fix perf probe to show which probe point is not found.
With out this patch, it shows just "No probe point found."
This doesn't help users if they specify several probes.
e.g.

 # perf probe -f --add schedule --add test
  Fatal: No probe point found.

This patch makes error message more helpful as below.

 # perf probe --add schedule --add test
  Fatal: Probe point 'test' not found. - probe not added.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091215153247.17436.49068.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index b05d532..2ca6215 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -249,11 +249,12 @@
 	argv_free(argv);
 }
 
-int synthesize_perf_probe_event(struct probe_point *pp)
+/* Synthesize only probe point (not argument) */
+int synthesize_perf_probe_point(struct probe_point *pp)
 {
 	char *buf;
 	char offs[64] = "", line[64] = "";
-	int i, len, ret;
+	int ret;
 
 	pp->probes[0] = buf = zalloc(MAX_CMDLEN);
 	if (!buf)
@@ -274,10 +275,24 @@
 				 offs, pp->retprobe ? "%return" : "", line);
 	else
 		ret = e_snprintf(buf, MAX_CMDLEN, "%s%s", pp->file, line);
-	if (ret <= 0)
-		goto error;
-	len = ret;
+	if (ret <= 0) {
+error:
+		free(pp->probes[0]);
+		pp->probes[0] = NULL;
+	}
+	return ret;
+}
 
+int synthesize_perf_probe_event(struct probe_point *pp)
+{
+	char *buf;
+	int i, len, ret;
+
+	len = synthesize_perf_probe_point(pp);
+	if (len < 0)
+		return 0;
+
+	buf = pp->probes[0];
 	for (i = 0; i < pp->nr_args; i++) {
 		ret = e_snprintf(&buf[len], MAX_CMDLEN - len, " %s",
 				 pp->args[i]);
@@ -290,6 +305,7 @@
 	return pp->found;
 error:
 	free(pp->probes[0]);
+	pp->probes[0] = NULL;
 
 	return ret;
 }
@@ -319,6 +335,7 @@
 	return pp->found;
 error:
 	free(pp->probes[0]);
+	pp->probes[0] = NULL;
 
 	return ret;
 }
@@ -418,7 +435,7 @@
 /* List up current perf-probe events */
 void show_perf_probe_events(void)
 {
-	int fd, nr;
+	int fd;
 	struct probe_point pp;
 	struct strlist *rawlist;
 	struct str_node *ent;
@@ -430,10 +447,7 @@
 	strlist__for_each(ent, rawlist) {
 		parse_trace_kprobe_event(ent->s, &pp);
 		/* Synthesize only event probe point */
-		nr = pp.nr_args;
-		pp.nr_args = 0;
-		synthesize_perf_probe_event(&pp);
-		pp.nr_args = nr;
+		synthesize_perf_probe_point(&pp);
 		/* Show an event */
 		show_perf_probe_event(pp.event, pp.probes[0], &pp);
 		clear_probe_point(&pp);