From: Tom de Vries <tdevries@suse.de>
To: gdb-patches@sourceware.org
Cc: Simon Marchi <simon.marchi@polymtl.ca>
Subject: [PATCH] [gdb/build] Fix frame_list position in frame.c
Date: Wed, 3 May 2023 19:58:26 +0200 [thread overview]
Message-ID: <20230503175826.4242-1-tdevries@suse.de> (raw)
In commit 995a34b1772 ("Guard against frame.c destructors running before
frame-info.c's") the following problem was addressed.
The frame_info_ptr destructor:
...
~frame_info_ptr ()
{
frame_list.erase (frame_list.iterator_to (*this));
}
...
uses frame_list, which is a static member of class frame_info_ptr,
instantiated in frame-info.c:
...
intrusive_list<frame_info_ptr> frame_info_ptr::frame_list;
...
Then there's a static frame_info_pointer variable named selected_frame in
frame.c:
...
static frame_info_ptr selected_frame;
...
Because the destructor of selected_frame uses frame_list, its destructor needs
to be called before the destructor of frame_list.
But because they're in different compilation units, the initialization order and
consequently destruction order is not guarantueed.
The commit fixed this by handling the case that the destructor of frame_list
is called first, adding a check on is_linked ():
...
~frame_info_ptr ()
{
- frame_list.erase (frame_list.iterator_to (*this));
+ /* If this node has static storage, it may be deleted after
+ frame_list. Attempting to erase ourselves would then trigger
+ internal errors, so make sure we are still linked first. */
+ if (is_linked ())
+ frame_list.erase (frame_list.iterator_to (*this));
}
...
However, since then frame_list has been moved into frame.c, and
initialization/destruction order is guarantueed inside a compilation unit.
Revert aforementioned commit, and fix the destruction order problem by moving
frame_list before selected_frame.
Reverting the commit is another way of fixing the already fixed
Wdangling-pointer warning reported in PR build/30413, in a different way than
commit 9b0ccb1ebae ("Pass const frame_info_ptr reference for
skip_[language_]trampoline").
Tested on x86_64-linux.
PR build/30413
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30413
---
gdb/frame.c | 11 +++++++----
gdb/frame.h | 9 ++++-----
2 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/gdb/frame.c b/gdb/frame.c
index 36fb02f3c8e..531eadf3d54 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -1733,6 +1733,13 @@ get_current_frame (void)
static frame_id selected_frame_id = null_frame_id;
static int selected_frame_level = -1;
+/* See frame.h. This definition should come before any definition of a static
+ frame_info_ptr, to ensure that frame_list is destroyed after any static
+ frame_info_ptr. This is necessary because the destructor of frame_info_ptr
+ uses frame_list. */
+
+intrusive_list<frame_info_ptr> frame_info_ptr::frame_list;
+
/* The cached frame_info object pointing to the selected frame.
Looked up on demand by get_selected_frame. */
static frame_info_ptr selected_frame;
@@ -3275,10 +3282,6 @@ maintenance_print_frame_id (const char *args, int from_tty)
/* See frame-info-ptr.h. */
-intrusive_list<frame_info_ptr> frame_info_ptr::frame_list;
-
-/* See frame-info-ptr.h. */
-
frame_info_ptr::frame_info_ptr (struct frame_info *ptr)
: m_ptr (ptr)
{
diff --git a/gdb/frame.h b/gdb/frame.h
index 6ed8db0af56..ed19dfdc090 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -254,11 +254,10 @@ class frame_info_ptr : public intrusive_list_node<frame_info_ptr>
~frame_info_ptr ()
{
- /* If this node has static storage, it may be deleted after
- frame_list. Attempting to erase ourselves would then trigger
- internal errors, so make sure we are still linked first. */
- if (is_linked ())
- frame_list.erase (frame_list.iterator_to (*this));
+ /* If this node has static storage, it should be be deleted before
+ frame_list. Verify this by checking that it is still in the list. */
+ gdb_assert (is_linked ());
+ frame_list.erase (frame_list.iterator_to (*this));
}
frame_info_ptr &operator= (const frame_info_ptr &other)
base-commit: 2ad00a4b42f89b61fdab24940b67713daf81c988
--
2.35.3
next reply other threads:[~2023-05-03 17:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-03 17:58 Tom de Vries [this message]
2023-05-03 18:47 ` Simon Marchi
2023-05-03 19:45 ` Tom de Vries
2023-05-04 9:01 ` Kévin Le Gouguec
2023-05-04 9:12 ` Tom de Vries
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