perf machine: Search for modules in %s/lib/modules/%s

Modules installed outside of the kernel's build system should go into
"%s/lib/modules/%s/extra", but at present, perf will only look at them
when they are in "%s/lib/modules/%s/kernel". Lets encourage good
citizenship by relaxing this requirement to "%s/lib/modules/%s". This
way open source modules that are out-of-tree have no incentive to start
populating a directory reserved for in-kernel modules and I can stop
hex-editing my system's perf binary when profiling OSS out-of-tree
modules.

Feedback from Namhyung Kim correctly revealed that the hex-edits that I
had been doing meant that perf was also traversing the build and source
symlinks in %s/lib/modules/%s. That is undesireable, so we explicitly
exclude them from traversal with a minor tweak to the traversal routine.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Acked-by: Namhyung kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1398532675-13684-1-git-send-email-ryao@gentoo.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

1 files changed, 12 insertions, 4 deletions

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index a53cd0b8c151..27c2a5efe450 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -717,7 +717,7 @@ static char *get_kernel_version(const char *root_dir)
 }
 
 static int map_groups__set_modules_path_dir(struct map_groups *mg,
-                                const char *dir_name)
+                                const char *dir_name, int depth)
 {
         struct dirent *dent;
         DIR *dir = opendir(dir_name);
@@ -742,7 +742,15 @@ static int map_groups__set_modules_path_dir(struct map_groups *mg,
                             !strcmp(dent->d_name, ".."))
                                 continue;
 
-                        ret = map_groups__set_modules_path_dir(mg, path);
+                        /* Do not follow top-level source and build symlinks */
+                        if (depth == 0) {
+                                if (!strcmp(dent->d_name, "source") ||
+                                    !strcmp(dent->d_name, "build"))
+                                        continue;
+                        }
+
+                        ret = map_groups__set_modules_path_dir(mg, path,
+                                                               depth + 1);
                         if (ret < 0)
                                 goto out;
                 } else {
@@ -786,11 +794,11 @@ static int machine__set_modules_path(struct machine *machine)
         if (!version)
                 return -1;
 
-        snprintf(modules_path, sizeof(modules_path), "%s/lib/modules/%s/kernel",
+        snprintf(modules_path, sizeof(modules_path), "%s/lib/modules/%s",
                  machine->root_dir, version);
         free(version);
 
-        return map_groups__set_modules_path_dir(&machine->kmaps, modules_path);
+        return map_groups__set_modules_path_dir(&machine->kmaps, modules_path, 0);
 }
 
 static int machine__create_module(void *arg, const char *name, u64 start)