perf tool: save cmdline from user in file header vs what is passed to record

A number of builtin commands process some user args and then pass the rest to cmd_record. cmd_record then saves argc/argv that it receives into the header of the perf data file. But this loses the arguments handled by the first command -- ie., the real command line from the user. This patch saves the command line as typed by the user rather than what was passed to cmd_record.

As an example consider the command:

$ perf kvm --guest --host --guestmount=/tmp/guest-mount record
    -fo /tmp/perf.data -ag -- sleep 10

Currently the command saved to the header is:
cmdline : /tmp/p3.5/perf record -o perf.data.kvm -fo /tmp/perf.data -ag -- sleep 1

(ignore the duplicated -o -- the first would be yet another bug with perf-kvm).

With this patch the command line saved to the header is:
cmdline : /tmp/p3.5/perf kvm --guest --host --guestmount=/tmp/guest-mount
record -fo /tmp/perf.data -ag -- sleep 1

v2: simplified to saving the command in parse_options per Stephane's suggestion

Signed-off-by David Ahern <[email protected]>

CC Arnaldo Carvalho de Melo <[email protected]>

Cc Ingo Molnar <[email protected]>

Cc Jiri Olsa <[email protected]>

Cc Namhyung Kim <[email protected]>

Cc Stephane Eranian <[email protected]>

Cc Frederic Weisbecker <[email protected]>

Cc Peter Zijlstra <[email protected]>

---
 tools/perf/builtin-record.c     |    2 --
 tools/perf/util/header.c        |    9 +++++++++
 tools/perf/util/parse-options.c |    3 +++
 3 files changed, 12 insertions(+), 2 deletions(-)

tools/perf/builtin-record.c +0 -2

index f5a6452..77adcd8 100644
@@ -844,8 +844,6 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
 	struct perf_record *rec = &record;
 	char errbuf[BUFSIZ];
 
-	perf_header__set_cmdline(argc, argv);
-
 	evsel_list = perf_evlist__new(NULL, NULL);
 	if (evsel_list == NULL)
 		return -ENOMEM;

tools/perf/util/header.c +9 -0

index 5a47aba..99e410c 100644
@@ -174,6 +174,15 @@ perf_header__set_cmdline(int argc, const char **argv)
 {
 	int i;
 
+	/* 
+	 * If header_argv has already been set, do not override it.
+	 * This allows a command to set the cmdline, parse args and
+	 * then call another builtin function that implements a
+	 * command -- e.g, cmd_kvm calling cmd_record.
+	 */
+	if (header_argv)
+		return 0;
+
 	header_argc = (u32)argc;
 
 	/* do not include NULL termination */

tools/perf/util/parse-options.c +3 -0

index 99d02aa..594f8fa 100644
@@ -1,6 +1,7 @@
 #include "util.h"
 #include "parse-options.h"
 #include "cache.h"
+#include "header.h"
 
 #define OPT_SHORT 1
 #define OPT_UNSET 2

@@ -413,6 +414,8 @@ int parse_options(int argc, const char **argv, const struct option *options,
 {
 	struct parse_opt_ctx_t ctx;
 
+	perf_header__set_cmdline(argc, argv);
+
 	parse_options_start(&ctx, argc, argv, flags);
 	switch (parse_options_step(&ctx, options, usagestr)) {
 	case PARSE_OPT_HELP:

Signature · 1 line

1.7.10.1

Can you please state for what branch, perf/urgent (i.e. current merge window) or perf/core (next), this is intended? I usually have been making the call, but having feedback from the submitter can help things and help meet expectations more frequently.

I'd say this one should be for perf/core, as it is not so critical, what do you think?