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* [PATCH] perf/probe: Skip same probe address
@ 2019-09-19  3:41 Masami Hiramatsu
  2019-09-20 18:26 ` Arnaldo Carvalho de Melo
  2019-09-22 10:52 ` [tip: perf/urgent] perf probe: Skip same probe address for a given line tip-bot2 for Masami Hiramatsu
  0 siblings, 2 replies; 3+ messages in thread
From: Masami Hiramatsu @ 2019-09-19  3:41 UTC (permalink / raw)
  To: Arnaldo Carvalho de Melo
  Cc: Wang Nan, Jiri Olsa, Namhyung Kim, Masami Hiramatsu, linux-kernel

Fix to skip making a same probe address on given line.

Since dwarf line info contains several entries for one line
with different column, perf probe will make a different
probe on same address if user specifies a probe point by
"function:line" or "file:line".

e.g.
 $ perf probe -D kernel_read:8
 p:probe/kernel_read_L8 kernel_read+39
 p:probe/kernel_read_L8_1 kernel_read+39

This skips such duplicated probe address.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 tools/perf/util/probe-finder.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 025fc4491993..02ca95deaf2c 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1244,6 +1244,17 @@ static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
 	return n;
 }
 
+static bool trace_event_finder_overlap(struct trace_event_finder *tf)
+{
+	int i;
+
+	for (i = 0; i < tf->ntevs; i++) {
+		if (tf->pf.addr == tf->tevs[i].point.address)
+			return true;
+	}
+	return false;
+}
+
 /* Add a found probe point into trace event list */
 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
 {
@@ -1254,6 +1265,14 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
 	struct perf_probe_arg *args = NULL;
 	int ret, i;
 
+	/*
+	 * For some reason (e.g. different column assigned to same address)
+	 * This callback can be called with the address which already passed.
+	 * Ignore it first.
+	 */
+	if (trace_event_finder_overlap(tf))
+		return 0;
+
 	/* Check number of tevs */
 	if (tf->ntevs == tf->max_tevs) {
 		pr_warning("Too many( > %d) probe point found.\n",


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2019-09-19  3:41 [PATCH] perf/probe: Skip same probe address Masami Hiramatsu
2019-09-20 18:26 ` Arnaldo Carvalho de Melo
2019-09-22 10:52 ` [tip: perf/urgent] perf probe: Skip same probe address for a given line tip-bot2 for Masami Hiramatsu

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