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Subject[PATCH AUTOSEL 4.14 047/130] perf trace: Filter own pid to avoid a feedback look in 'perf trace record -a'
Date
From: Arnaldo Carvalho de Melo <acme@redhat.com>

[ Upstream commit 7fbfe22cf4cfe01a88704dd76ca65d108039d297 ]

When doing a system wide 'perf trace record' we need, just like in 'perf
trace' live mode, to filter out perf trace's own pid, so set up a
tracepoint filter for the raw_syscalls tracepoints right after adding
them to the argv array that is set up to then call cmd_record().

Reported-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-uysx5w8f2y5ndoln5cq370tv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/builtin-trace.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index b224bf3f2b994..63a35036321bb 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2055,21 +2055,23 @@ static int trace__record(struct trace *trace, int argc, const char **argv)
"-m", "1024",
"-c", "1",
};
-
+ pid_t pid = getpid();
+ char *filter = asprintf__tp_filter_pids(1, &pid);
const char * const sc_args[] = { "-e", };
unsigned int sc_args_nr = ARRAY_SIZE(sc_args);
const char * const majpf_args[] = { "-e", "major-faults" };
unsigned int majpf_args_nr = ARRAY_SIZE(majpf_args);
const char * const minpf_args[] = { "-e", "minor-faults" };
unsigned int minpf_args_nr = ARRAY_SIZE(minpf_args);
+ int err = -1;

- /* +1 is for the event string below */
- rec_argc = ARRAY_SIZE(record_args) + sc_args_nr + 1 +
+ /* +3 is for the event string below and the pid filter */
+ rec_argc = ARRAY_SIZE(record_args) + sc_args_nr + 3 +
majpf_args_nr + minpf_args_nr + argc;
rec_argv = calloc(rec_argc + 1, sizeof(char *));

- if (rec_argv == NULL)
- return -ENOMEM;
+ if (rec_argv == NULL || filter == NULL)
+ goto out_free;

j = 0;
for (i = 0; i < ARRAY_SIZE(record_args); i++)
@@ -2086,11 +2088,13 @@ static int trace__record(struct trace *trace, int argc, const char **argv)
rec_argv[j++] = "syscalls:sys_enter,syscalls:sys_exit";
else {
pr_err("Neither raw_syscalls nor syscalls events exist.\n");
- free(rec_argv);
- return -1;
+ goto out_free;
}
}

+ rec_argv[j++] = "--filter";
+ rec_argv[j++] = filter;
+
if (trace->trace_pgfaults & TRACE_PFMAJ)
for (i = 0; i < majpf_args_nr; i++)
rec_argv[j++] = majpf_args[i];
@@ -2102,7 +2106,11 @@ static int trace__record(struct trace *trace, int argc, const char **argv)
for (i = 0; i < (unsigned int)argc; i++)
rec_argv[j++] = argv[i];

- return cmd_record(j, rec_argv);
+ err = cmd_record(j, rec_argv);
+out_free:
+ free(filter);
+ free(rec_argv);
+ return err;
}

static size_t trace__fprintf_thread_summary(struct trace *trace, FILE *fp);
--
2.20.1
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