This is the mail archive of the mailing list for the GDB project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [RFA] dcache invalidate fix

Doug Evans wrote:
On Tue, Nov 10, 2009 at 1:33 PM, Michael Snyder <> wrote:
Doug, I'm vague about this, but it seems right and it fixes the
bug that I'm running into.

It seems like dcache_invalidate_line needs to remove the block
from the in use list at the same time as adding it to the freed

The problem that bit me was getting the two lists cross-linked,
which eventually led to an infinite loop behavior in dcache_invalidate.

2009-11-10 Michael Snyder <>

       * dcache.c (dcache_invalidate_line): Remove block from used list
       when adding it to freed list.

Index: dcache.c
RCS file: /cvs/src/src/gdb/dcache.c,v
retrieving revision 1.37
diff -u -p -r1.37 dcache.c
--- dcache.c    10 Nov 2009 18:36:50 -0000      1.37
+++ dcache.c    10 Nov 2009 21:31:03 -0000
@@ -167,10 +167,18 @@ dcache_invalidate_line (DCACHE *dcache,

  if (db)
+      struct dcache_block *db2;
      splay_tree_remove (dcache->tree, (splay_tree_key) db->addr);
      db->newer = dcache->freelist;
      dcache->freelist = db;
+      /* Remove db from dcache in-use chain.  */
+      for (db2 = dcache->oldest; db2; db2 = db2->newer)
+       if (db2->newer == db)
+         {
+           dcache->newest = db2;
+           db2->newer = NULL;
+         }

Blech. Thanks for catching this.

The list will contain 4096 elements at this point so I think we need
to do something different.
The following comes to mind.

I'll check it in in a few days if there are no objections.

FYI, this fixes the problem that caused me to look into it. Thanks, Michael

2009-11-11 Doug Evans <>

        * dcache.c (dcache_block): Replace member newer with next,prev.
        (dcache_struct): Delete member newest.
	(block_func): New typedef.
        (append_block, remove_block, for_each_block): New functions.
        (invalidate_block, free_block): New functions.
        (dcache_invalidate): Update
        (dcache_invalidate_line, dcache_alloc): Update to use new list
        (dcache_free): Ditto.  Fix memory leak.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]