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Subject[PATCH -tip 11/14] perf probe: Reject second attempt of adding same-name event
Date
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: Ingo Molnar <mingo@elte.hu>
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: Frederic Weisbecker <fweisbec@gmail.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>
---
tools/perf/builtin-probe.c | 6 +++++-
tools/perf/util/probe-event.c | 24 +++++++++++++++++++++---
tools/perf/util/probe-event.h | 3 ++-
3 files changed, 28 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 4f768f3..4d232cb 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -61,6 +61,7 @@ static struct {
char *release;
bool need_dwarf;
bool list_events;
+ bool force_add;
int nr_probe;
struct probe_point probes[MAX_PROBES];
struct strlist *dellist;
@@ -192,6 +193,8 @@ static const struct option options[] = {
#endif
"\t\t\tkprobe-tracer argument format.)\n",
opt_add_probe_event),
+ OPT_BOOLEAN('f', "force", &session.force_add, "forcibly add events"
+ " with existing name"),
OPT_END()
};

@@ -296,7 +299,8 @@ end_dwarf:
}

/* Settng up probe points */
- add_trace_kprobe_events(session.probes, session.nr_probe);
+ add_trace_kprobe_events(session.probes, session.nr_probe,
+ session.force_add);
return 0;
}

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 0b769bc..e74ecfc 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. */
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 8bb22f5..8fd3052 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -10,7 +10,8 @@ extern void parse_perf_probe_event(const char *str, struct probe_point *pp,
extern int synthesize_perf_probe_event(struct probe_point *pp);
extern void parse_trace_kprobe_event(const char *str, struct probe_point *pp);
extern int synthesize_trace_kprobe_event(struct probe_point *pp);
-extern void add_trace_kprobe_events(struct probe_point *probes, int nr_probes);
+extern void add_trace_kprobe_events(struct probe_point *probes, int nr_probes,
+ bool force_add);
extern void del_trace_kprobe_events(struct strlist *dellist);
extern void show_perf_probe_events(void);


--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com


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