In some cases unloading a module with dlclose can fail to update the symbol
search list for the remaining modules, leading to a situation where symbols
are referenced after the library has been removed from the symbol map.  The
most commonly encountered example of this is the error_category destructor
in libstdc++ not getting called until the exit finalizers are run, resulting
in:

symbol lookup error: /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.0/libstdc++.so.6:
undefined symbol: _ZNSt14error_categoryD2Ev, version GLIBCXX_3.4.15

https://bugs.gentoo.org/364077
https://bugzilla.redhat.com/593675
http://sourceware.org/ml/libc-hacker/2010-05/msg00007.html
http://gcc.gnu.org/ml/gcc-help/2011-07/msg00099.html


2010-05-26  Andreas Schwab  <schwab@redhat.com>

	* elf/dl-close.c (_dl_close_worker): Reset private search list if
	it wasn't used.

--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -421,6 +421,13 @@ _dl_close_worker (struct link_map *map)
 
 	      imap->l_scope_max = new_size;
 	    }
+	  else if (new_list != NULL)
+	    {
+	      /* We didn't change the scope array, so reset the search
+		 list.  */
+	      imap->l_searchlist.r_list = NULL;
+	      imap->l_searchlist.r_nlist = 0;
+	    }
 
 	  /* The loader is gone, so mark the object as not having one.
 	     Note: l_idx != IDX_STILL_USED -> object will be removed.  */