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Subject[tip: perf/urgent] perf probe: Skip same probe address for a given line
The following commit has been merged into the perf/urgent branch of tip:

Commit-ID: 1a375ae7659ab740d4c885ea98c1659b8a6e2071
Gitweb: https://git.kernel.org/tip/1a375ae7659ab740d4c885ea98c1659b8a6e2071
Author: Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Thu, 19 Sep 2019 12:41:10 +09:00
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitterDate: Fri, 20 Sep 2019 15:22:00 -03:00

perf probe: Skip same probe address for a given line

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

Since a 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 addresses.

Committer testing:

# uname -a
Linux quaco 5.3.0+ #2 SMP Thu Sep 19 16:13:22 -03 2019 x86_64 x86_64 x86_64 GNU/Linux
#

Before:

# perf probe -D kernel_read:8
p:probe/kernel_read _text+3115191
p:probe/kernel_read_1 _text+3115191
#

After:

# perf probe -D kernel_read:8
p:probe/kernel_read _text+3115191
#

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lore.kernel.org/lkml/156886447061.10772.4261569305869149178.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
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 505905f..cd9f95e 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1245,6 +1245,17 @@ 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)
{
@@ -1255,6 +1266,14 @@ 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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