gdb/gdb-stale-frame_info.patch

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From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
From: Fedora GDB patches <invalid@email.com>
Date: Fri, 27 Oct 2017 21:07:50 +0200
Subject: workaround stale frame_info * (PR 13866)
FileName: gdb-stale-frame_info.patch
;; Workaround crashes from stale frame_info pointer (BZ 804256).
;;=push+jan
http://sourceware.org/ml/gdb-patches/2012-04/msg00058.html
Hi,
I did not look at which commit caused this regression but apparently it was
introduced at least with multi-inferiors.
I understand this fix is not right fix of the crash; but in most GDB cases one
does not use multi-inferior so why to regress single-inferior by it.
Some more simple solutions still fix the single-inferior mode but they
regressed the multi-inferior mode
gdb.threads/no-unwaited-for-left.exp
gdb.multi/base.exp
so I had to put there that sorting magic.
With proper C++ sanity check of stale live frame_info references the testcase
would be simple without the "frame_garbage_collection" reproducer below.
It is also reproducible just with valgrind but regularly running the whole
testsuite under valgrind I did not find feasible.
No regressions on {x86_64,x86_64-m32,i686}-fedora17-linux-gnu.
Thanks,
Jan
gdb/
2012-04-04 Jan Kratochvil <jan.kratochvil@redhat.com>
Workaround PR backtrace/13866.
* progspace.c (switch_to_program_space_and_thread): Try not to call
switch_to_thread.
diff --git a/gdb/progspace-and-thread.c b/gdb/progspace-and-thread.c
--- a/gdb/progspace-and-thread.c
+++ b/gdb/progspace-and-thread.c
@@ -23,15 +23,29 @@
void
switch_to_program_space_and_thread (program_space *pspace)
{
- inferior *inf = find_inferior_for_program_space (pspace);
+ inferior *inf = current_inferior ();
+
+ if (inf->pspace != pspace)
+ inf = find_inferior_for_program_space (pspace);
if (inf != NULL && inf->pid != 0)
{
thread_info *tp = any_live_thread_of_process (inf->pid);
+ thread_info *current_tp = NULL;
+
+ if (ptid_get_pid (inferior_ptid) == inf->pid)
+ current_tp = find_thread_ptid (inferior_ptid);
if (tp != NULL)
{
- switch_to_thread (tp->ptid);
+ /* Prefer primarily thread not THREAD_EXITED and secondarily thread
+ not EXECUTING. */
+ if (current_tp == NULL
+ || (tp->state != THREAD_EXITED
+ && current_tp->state == THREAD_EXITED)
+ || (!tp->executing && current_tp->executing))
+ switch_to_thread (tp->ptid);
+
/* Switching thread switches pspace implicitly. We're
done. */
return;