PING: [PATCH] release the sorted FDE array when deregistering a frame [PR109685]

PING: [PATCH] release the sorted FDE array when deregistering a frame [PR109685]

[Thomas Neumann]

Summary: The old linear scan logic called free while searching the list 
of frames. The atomic fast path finds the frame quickly, but forgot the 
free call. This patches adds the missing free. Bugzilla #109685.

See:
https://gcc.gnu.org/pipermail/gcc-patches/2023-May/617245.html

Best

Thomas

Re: PING: [PATCH] release the sorted FDE array when deregistering a frame [PR109685]

[Jeff Law]

On 5/12/23 09:19, Thomas Neumann via Gcc-patches wrote:
> Summary: The old linear scan logic called free while searching the list 
> of frames. The atomic fast path finds the frame quickly, but forgot the 
> free call. This patches adds the missing free. Bugzilla #109685.
> 
> See:
> https://gcc.gnu.org/pipermail/gcc-patches/2023-May/617245.html
I think this needs an update given the other changes in this space.

jeff

[PATCH v2] release the sorted FDE array when deregistering a frame [PR109685]

[Thomas Neumann]

Am 19.05.23 um 19:26 schrieb Jeff Law:
>> See:
>> https://gcc.gnu.org/pipermail/gcc-patches/2023-May/617245.html
> I think this needs an update given the other changes in this space.
> 
> jeff

I have included the updated the patch below.



The atomic fastpath bypasses the code that releases the sort
array which was lazily allocated during unwinding. We now
check after deregistering if there is an array to free.

libgcc/ChangeLog:
	* unwind-dw2-fde.c: Free sort array in atomic fast path.
---
  libgcc/unwind-dw2-fde.c | 6 ++++++
  1 file changed, 6 insertions(+)

diff --git a/libgcc/unwind-dw2-fde.c b/libgcc/unwind-dw2-fde.c
index a5786bf729c..32b9e64a1c8 100644
--- a/libgcc/unwind-dw2-fde.c
+++ b/libgcc/unwind-dw2-fde.c
@@ -241,6 +241,12 @@ __deregister_frame_info_bases (const void *begin)
    // And remove
    ob = btree_remove (&registered_frames, range[0]);
    bool empty_table = (range[1] - range[0]) == 0;
+
+  // Deallocate the sort array if any.
+  if (ob && ob->s.b.sorted)
+    {
+      free (ob->u.sort);
+    }
  #else
    init_object_mutex_once ();
    __gthread_mutex_lock (&object_mutex);
-- 
2.39.2