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SubjectRe: [PATCH 1/1] perf record: We should fork only if a program was specified to run
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On Fri, 2009-12-18 at 18:42 -0200, Arnaldo Carvalho de Melo wrote:
> From: Arnaldo Carvalho de Melo <acme@redhat.com>
>
> IOW: Now 'perf record -a' works, this was a bug introduced in:
>
> 856e96608a72412d319e498a3a7c557571f811bd
> "perf record: Properly synchronize child creation"
>
> Reported-by: Pekka Enberg <penberg@cs.helsinki.fi>
> Cc: Frédéric Weisbecker <fweisbec@gmail.com>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Paul Mackerras <paulus@samba.org>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> tools/perf/builtin-record.c | 9 +++++----
> 1 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 63136d0..90eedd9 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -402,7 +402,7 @@ static void atexit_header(void)
> perf_header__write(&session->header, output, true);
> }
>
> -static int __cmd_record(int argc __used, const char **argv)
> +static int __cmd_record(int argc, const char **argv)
> {
> int i, counter;
> struct stat st;
> @@ -422,7 +422,8 @@ static int __cmd_record(int argc __used, const char **argv)
> signal(SIGCHLD, sig_handler);
> signal(SIGINT, sig_handler);
>
> - if (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0) {
> + if (target_pid == -1 && argc > 0 &&
> + (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0)) {
> perror("failed to create pipes");
> exit(-1);
> }

Why bother?

> @@ -483,7 +484,7 @@ static int __cmd_record(int argc __used, const char **argv)
>
> atexit(atexit_header);
>
> - if (target_pid == -1) {
> + if (target_pid == -1 && argc > 0) {
> pid = fork();
> if (pid < 0) {
> perror("failed to fork");

I'd write:

target_pid == -1 && !system_wide

> @@ -667,7 +668,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
>
> argc = parse_options(argc, argv, options, record_usage,
> PARSE_OPT_STOP_AT_NON_OPTION);
> - if (!argc && target_pid == -1 && (!system_wide || profile_cpu == -1))
> + if (!argc && target_pid == -1 && !system_wide)
> usage_with_options(record_usage, options);
>
> symbol__init();

Right, so I was thinking -C would be enough to also start profiling..
clearly messed up the logic though :/

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