perf probe: Reject second attempt of adding same-name event

Reject second attempt of adding same-name event. This patch
also provides --force option which allows user to add additional
probe events on the same-name event.

e.g.
(the first attempt : success)
 ./perf probe schedule
 Added new event:
   probe:schedule                           (on schedule+0)

(the second attempt : failure)
 ./perf probe schedule:11
 Error: event "schedule" already exists. (Use -f to force duplicates.)
   Fatal: Can't add new event.

(the second attempt with -f : successfully added)
 ./perf probe -f schedule:11
 Added new event:
   probe:schedule_1                         (on schedule+45)

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: <20091215153225.17436.15166.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 21 insertions, 3 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 3b4cf456165c..b05d532a4e4c 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -482,7 +482,7 @@ static void write_trace_kprobe_event(int fd, const char *buf)
 }
 
 static void get_new_event_name(char *buf, size_t len, const char *base,
-                               struct strlist *namelist)
+                               struct strlist *namelist, bool allow_suffix)
 {
         int i, ret;
 
@@ -493,6 +493,12 @@ static void get_new_event_name(char *buf, size_t len, const char *base,
         if (!strlist__has_entry(namelist, buf))
                 return;
 
+        if (!allow_suffix) {
+                pr_warning("Error: event \"%s\" already exists. "
+                           "(Use -f to force duplicates.)\n", base);
+                die("Can't add new event.");
+        }
+
         /* Try to add suffix */
         for (i = 1; i < MAX_EVENT_INDEX; i++) {
                 ret = e_snprintf(buf, len, "%s_%d", base, i);
@@ -505,13 +511,15 @@ static void get_new_event_name(char *buf, size_t len, const char *base,
                 die("Too many events are on the same function.");
 }
 
-void add_trace_kprobe_events(struct probe_point *probes, int nr_probes)
+void add_trace_kprobe_events(struct probe_point *probes, int nr_probes,
+                             bool force_add)
 {
         int i, j, fd;
         struct probe_point *pp;
         char buf[MAX_CMDLEN];
         char event[64];
         struct strlist *namelist;
+        bool allow_suffix;
 
         fd = open_kprobe_events(O_RDWR, O_APPEND);
         /* Get current event names */
@@ -524,9 +532,12 @@ void add_trace_kprobe_events(struct probe_point *probes, int nr_probes)
                 if (!pp->group)
                         pp->group = strdup(PERFPROBE_GROUP);
                 DIE_IF(!pp->event || !pp->group);
+                /* If force_add is true, suffix search is allowed */
+                allow_suffix = force_add;
                 for (i = 0; i < pp->found; i++) {
                         /* Get an unused new event name */
-                        get_new_event_name(event, 64, pp->event, namelist);
+                        get_new_event_name(event, 64, pp->event, namelist,
+                                           allow_suffix);
                         snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s\n",
                                  pp->retprobe ? 'r' : 'p',
                                  pp->group, event,
@@ -538,6 +549,13 @@ void add_trace_kprobe_events(struct probe_point *probes, int nr_probes)
                         show_perf_probe_event(event, buf, pp);
                         /* Add added event name to namelist */
                         strlist__add(namelist, event);
+                        /*
+                         * Probes after the first probe which comes from same
+                         * user input are always allowed to add suffix, because
+                         * there might be several addresses corresponding to
+                         * one code line.
+                         */
+                        allow_suffix = true;
                 }
         }
         /* Show how to use the event. */