perf record: We should fork only if a program was specified to run

IOW: Now 'perf record -a' works, this was a bug introduced in:

856e96608a72412d319e498a3a7c557571f811bd
"perf record: Properly synchronize child creation"

Also fix the -C usage, i.e. allow for profiling all the tasks in
one CPU.

Reported-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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>
LKML-Reference: <1261957026-15580-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 63136d0534d450ef18a6bf65ee1d78275f41333b..265425322734eecfc3087a7be42a60960c89f2b0 100644 (file)
--- 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;
@@ -411,6 +411,7 @@ static int __cmd_record(int argc __used, const char **argv)
        int err;
        unsigned long waking = 0;
        int child_ready_pipe[2], go_pipe[2];
+       const bool forks = target_pid == -1 && argc > 0;
        char buf;
 
        page_size = sysconf(_SC_PAGE_SIZE);
@@ -422,7 +423,7 @@ 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 (forks && (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0)) {
                perror("failed to create pipes");
                exit(-1);
        }
@@ -483,7 +484,7 @@ static int __cmd_record(int argc __used, const char **argv)
 
        atexit(atexit_header);
 
-       if (target_pid == -1) {
+       if (forks) {
                pid = fork();
                if (pid < 0) {
                        perror("failed to fork");
@@ -550,7 +551,7 @@ static int __cmd_record(int argc __used, const char **argv)
                        return err;
        }
 
-       if (!system_wide)
+       if (!system_wide && profile_cpu == -1)
                event__synthesize_thread(pid, process_synthesized_event,
                                         session);
        else
@@ -569,7 +570,8 @@ static int __cmd_record(int argc __used, const char **argv)
        /*
         * Let the child rip
         */
-       close(go_pipe[1]);
+       if (forks)
+               close(go_pipe[1]);
 
        for (;;) {
                int hits = samples;
@@ -667,7 +669,7 @@ 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 && profile_cpu == -1)
                usage_with_options(record_usage, options);
 
        symbol__init();