perf record: Use WARN_ONCE to replace 'if' condition

Commits in a BPF patchkit will extract kernel and module synthesizing
code into a separated function and call it multiple times. This patch
replace 'if (err < 0)' using WARN_ONCE, makes sure the error message
show one time.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1456479154-136027-19-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 7d11162b6c41d1416de9ffec5001c2a1fc962c61..9dec7e529832a32c52eb7c7aac932f8994aae00e 100644 (file)
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -33,6 +33,7 @@
 #include "util/parse-regs-options.h"
 #include "util/llvm-utils.h"
 #include "util/bpf-loader.h"
+#include "asm/bug.h"
 
 #include <unistd.h>
 #include <sched.h>
@@ -615,17 +616,15 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 
        err = perf_event__synthesize_kernel_mmap(tool, process_synthesized_event,
                                                 machine);
-       if (err < 0)
-               pr_err("Couldn't record kernel reference relocation symbol\n"
-                      "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
-                      "Check /proc/kallsyms permission or run as root.\n");
+       WARN_ONCE(err < 0, "Couldn't record kernel reference relocation symbol\n"
+                          "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
+                          "Check /proc/kallsyms permission or run as root.\n");
 
        err = perf_event__synthesize_modules(tool, process_synthesized_event,
                                             machine);
-       if (err < 0)
-               pr_err("Couldn't record kernel module information.\n"
-                      "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
-                      "Check /proc/modules permission or run as root.\n");
+       WARN_ONCE(err < 0, "Couldn't record kernel module information.\n"
+                          "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
+                          "Check /proc/modules permission or run as root.\n");
 
        if (perf_guest) {
                machines__process_guests(&session->machines,