Add more comments to dlclose() algorithm.

The algorithm for scanning dependencies upon dlclose is
less than immediately obvious. This patch adds two bits
of comments that explain why you start the dependency
search at l_initfini[1], and why you need to restart
the search.

---

2013-05-09  Carlos O'Donell  <carlos@redhat.com>

	* elf/dl-close.c (_dl_close_worker): Add comments.

diff --git a/ChangeLog b/ChangeLog
index 619ce64..d9c38d2 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2013-05-09  Carlos O'Donell  <carlos@redhat.com>
+
+       * elf/dl-close.c (_dl_close_worker): Add comments.
+
 2013-05-09  Joseph Myers  <joseph@codesourcery.com>
 
        [BZ #15359]

diff --git a/elf/dl-close.c b/elf/dl-close.c
index c86f609..fe3014c 100644 (file)
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -183,6 +183,8 @@ _dl_close_worker (struct link_map *map)
       /* Mark all dependencies as used.  */
       if (l->l_initfini != NULL)
        {
+         /* We are always the zeroth entry, and since we don't include
+            ourselves in the dependency analysis start at 1.  */
          struct link_map **lp = &l->l_initfini[1];
          while (*lp != NULL)
            {
@@ -193,6 +195,10 @@ _dl_close_worker (struct link_map *map)
                  if (!used[(*lp)->l_idx])
                    {
                      used[(*lp)->l_idx] = 1;
+                     /* If we marked a new object as used, and we've
+                        already processed it, then we need to go back
+                        and process again from that point forward to
+                        ensure we keep all of its dependencies also.  */
                      if ((*lp)->l_idx - 1 < done_index)
                        done_index = (*lp)->l_idx - 1;
                    }