Re: [PATCH v2 1/2] Thread-safety improvements for bfd_check_format_matches

[Alan Modra <amodra@gmail.com>]

You need this or something like it on top of your patch, otherwise
the first element with PER_XVEC_NO_TARGET won't have targ set (and the
first element will be used for everything).

diff --git a/bfd/bfd.c b/bfd/bfd.c
index 80ce859d874..ace2f67954f 100644
--- a/bfd/bfd.c
+++ b/bfd/bfd.c
@@ -1574,10 +1574,10 @@ INTERNAL
 .  char message[];
 .};
 .
-.{* A list of per_xvec_message objects.  The targ field
-.   indicates which xvec this list holds; PER_XVEC_NO_TARGET
-.   indicates that this entry isn't yet used. The abfd field is
-.   only needed in the root entry of the list.  *}
+.{* A list of per_xvec_message objects.  The targ field indicates
+.   which xvec this list holds; PER_XVEC_NO_TARGET is only set for the
+.   root of the list and indicates that the entry isn't yet used.  The
+.   abfd field is only needed in the root entry of the list.  *}
 .struct per_xvec_messages
 .{
 .  bfd *abfd;
@@ -1600,12 +1600,15 @@ _bfd_per_xvec_warn (struct per_xvec_messages *messages, size_t alloc)
   struct per_xvec_messages *prev = NULL;
   struct per_xvec_messages *iter = messages;
 
-  for (iter = messages; iter != NULL; iter = iter->next)
-    {
-      if (iter->targ == targ || iter->targ == PER_XVEC_NO_TARGET)
-	break;
-      prev = iter;
-    }
+  if (iter->targ == PER_XVEC_NO_TARGET)
+    iter->targ = targ;
+  else
+    for (; iter != NULL; iter = iter->next)
+      {
+	if (iter->targ == targ)
+	  break;
+	prev = iter;
+      }
 
   if (iter == NULL)
     {
@@ -1618,8 +1621,6 @@ _bfd_per_xvec_warn (struct per_xvec_messages *messages, size_t alloc)
       iter->next = NULL;
       prev->next = iter;
     }
-  else if (iter->targ == NULL)
-    iter->targ = targ;
 
   struct per_xvec_message **m = &iter->messages;
   int count = 0;

-- 
Alan Modra
Australia Development Lab, IBM