perf probe: Fix error reported when offset without function

This patch fixes a bug that, when offset is provided but function is
lost, parse_perf_probe_point() will give a "" string as function name,
so the checking code at the end of parse_perf_probe_point() become
useless.  For example:

  # perf probe +0x1234
  Failed to find symbol  in kernel
    Error: Failed to add events.

After this patch:

  # perf probe +0x1234
  Semantic error :Offset requires an entry function.
    Error: Command Parse Error.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1440586666-235233-6-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 926bcecc4a44..eaacb58b9b36 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1194,9 +1194,13 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
                 *ptr++ = '\0';
         }
 
-        tmp = strdup(arg);
-        if (tmp == NULL)
-                return -ENOMEM;
+        if (arg[0] == '\0')
+                tmp = NULL;
+        else {
+                tmp = strdup(arg);
+                if (tmp == NULL)
+                        return -ENOMEM;
+        }
 
         if (file_spec)
                 pp->file = tmp;