perf probe: Use existing routine to look for a kernel module by dso->short_name

We have map_groups__find_by_name() to look at the list of modules that
are in place for a given machine, so use it instead of traversing the
machine dso list, which also includes DSOs for userspace.

When merging the user and kernel DSO lists a bug was introduced where
'perf probe' stopped being able to add probes to modules using its short
name:

  # perf probe -m usbnet --add usbnet_start_xmit
  usbnet_start_xmit is out of .text, skip it.
    Error: Failed to add events.
  #

With this fix it works again:

  # perf probe -m usbnet --add usbnet_start_xmit
  Added new event:
    probe:usbnet_start_xmit (on usbnet_start_xmit in usbnet)

  You can now use it in all perf tools, such as:

  	perf record -e probe:usbnet_start_xmit -aR sleep 1
  #

Reported-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Fixes: 3d39ac538629 ("perf machine: No need to have two DSOs lists")
Link: http://lkml.kernel.org/r/20150924015008.GE1897@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index eb5f18b754028e863e3b72970842cc33d2fb997d..c6f9af78f6f5f9651c6339bd3140221b9b951b6d 100644 (file)
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -270,12 +270,13 @@ static int kernel_get_module_dso(const char *module, struct dso **pdso)
        int ret = 0;
 
        if (module) {
-               list_for_each_entry(dso, &host_machine->dsos.head, node) {
-                       if (!dso->kernel)
-                               continue;
-                       if (strncmp(dso->short_name + 1, module,
-                                   dso->short_name_len - 2) == 0)
-                               goto found;
+               char module_name[128];
+
+               snprintf(module_name, sizeof(module_name), "[%s]", module);
+               map = map_groups__find_by_name(&host_machine->kmaps, MAP__FUNCTION, module_name);
+               if (map) {
+                       dso = map->dso;
+                       goto found;
                }
                pr_debug("Failed to find module %s.\n", module);
                return -ENOENT;