perf tools: Split up build id saving into fetch and write

We are saving the build id once we stop the profiling. And only
after doing that we know if we need to set that feature in the
header through the feature bitmap.

But if we want a proper feature support in the headers, using a
rule of offset/size pairs in sections, we need to know in
advance how many features we need to set in the headers, so that
we can reserve rooms for their section headers.

The current state doesn't allow that, as it forces us to first
save the build-ids to the file right after the datas instead of
planning any structured layout.

That's why this splits up the build-ids processing in two parts:
one that fetches the build-ids from the Dso objects, and one
that saves them into the file.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
LKML-Reference: <1257911467-28276-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 17 insertions, 24 deletions

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index a4d0bbef9a43..2f702c23f71a 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -174,29 +174,18 @@ static void do_write(int fd, void *buf, size_t size)
         }
 }
 
-static bool write_buildid_table(int fd)
+static void write_buildid_table(int fd, struct list_head *id_head)
 {
-        struct dso *pos;
-        bool have_buildid = false;
-
-        list_for_each_entry(pos, &dsos, node) {
-                struct build_id_event b;
-                size_t len;
-
-                if (filename__read_build_id(pos->long_name,
-                                            &b.build_id,
-                                            sizeof(b.build_id)) < 0)
-                        continue;
-                have_buildid = true;
-                memset(&b.header, 0, sizeof(b.header));
-                len = strlen(pos->long_name) + 1;
-                len = ALIGN(len, 64);
-                b.header.size = sizeof(b) + len;
-                do_write(fd, &b, sizeof(b));
-                do_write(fd, pos->long_name, len);
-        }
+        struct build_id_list *iter, *next;
+
+        list_for_each_entry_safe(iter, next, id_head, list) {
+                struct build_id_event *b = &iter->event;
 
-        return have_buildid;
+                do_write(fd, b, sizeof(*b));
+                do_write(fd, (void *)iter->dso_name, iter->len);
+                list_del(&iter->list);
+                free(iter);
+        }
 }
 
 static void
@@ -226,10 +215,14 @@ perf_header__adds_write(struct perf_header *self, int fd, bool at_exit)
         }
 
         if (at_exit) {
-                lseek(fd, self->data_offset + self->data_size, SEEK_SET);
-                if (write_buildid_table(fd))
+                LIST_HEAD(id_list);
+
+                if (fetch_build_id_table(&id_list)) {
+                        lseek(fd, self->data_offset + self->data_size, SEEK_SET);
                         perf_header__set_feat(self, HEADER_BUILD_ID);
-                lseek(fd, cur_offset, SEEK_SET);
+                        write_buildid_table(fd, &id_list);
+                        lseek(fd, cur_offset, SEEK_SET);
+                }
         }
 };