* [PATCH] [gdb/build] Fix frame_list position in frame.c
@ 2023-05-03 17:58 Tom de Vries
2023-05-03 18:47 ` Simon Marchi
0 siblings, 1 reply; 5+ messages in thread
From: Tom de Vries @ 2023-05-03 17:58 UTC (permalink / raw)
To: gdb-patches; +Cc: Simon Marchi
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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] [gdb/build] Fix frame_list position in frame.c
2023-05-03 17:58 [PATCH] [gdb/build] Fix frame_list position in frame.c Tom de Vries
@ 2023-05-03 18:47 ` Simon Marchi
2023-05-03 19:45 ` Tom de Vries
0 siblings, 1 reply; 5+ messages in thread
From: Simon Marchi @ 2023-05-03 18:47 UTC (permalink / raw)
To: Tom de Vries, gdb-patches
On 5/3/23 13:58, Tom de Vries wrote:
> 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
Spurious double space.
> + 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));
The assert is a bit redundant with the assertions in
intrusive_list::erase_element:
gdb_assert (elem_node->prev != INTRUSIVE_LIST_UNLINKED_VALUE);
gdb_assert (elem_node->next != INTRUSIVE_LIST_UNLINKED_VALUE);
I would maybe remove the assert, but keep the comment (at least the
first sentence)?
In any case, this LGTM, thanks for doing this.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Simon
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] [gdb/build] Fix frame_list position in frame.c
2023-05-03 18:47 ` Simon Marchi
@ 2023-05-03 19:45 ` Tom de Vries
2023-05-04 9:01 ` Kévin Le Gouguec
0 siblings, 1 reply; 5+ messages in thread
From: Tom de Vries @ 2023-05-03 19:45 UTC (permalink / raw)
To: Simon Marchi, gdb-patches
On 5/3/23 20:47, Simon Marchi wrote:
> On 5/3/23 13:58, Tom de Vries wrote:
>> 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
>
> Spurious double space.
>
Fixed.
>> + 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));
>
> The assert is a bit redundant with the assertions in
> intrusive_list::erase_element:
>
> gdb_assert (elem_node->prev != INTRUSIVE_LIST_UNLINKED_VALUE);
> gdb_assert (elem_node->next != INTRUSIVE_LIST_UNLINKED_VALUE);
>
> I would maybe remove the assert, but keep the comment (at least the
> first sentence)?
>
Ack, I checked by doing:
...
+static frame_info_ptr bad_frame;
intrusive_list<frame_info_ptr> frame_info_ptr::frame_list;
...
and indeed those assertions trigger, so done.
> In any case, this LGTM, thanks for doing this.
>
> Approved-By: Simon Marchi <simon.marchi@efficios.com>
>
Committed, thanks for the review.
- Tom
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] [gdb/build] Fix frame_list position in frame.c
2023-05-03 19:45 ` Tom de Vries
@ 2023-05-04 9:01 ` Kévin Le Gouguec
2023-05-04 9:12 ` Tom de Vries
0 siblings, 1 reply; 5+ messages in thread
From: Kévin Le Gouguec @ 2023-05-04 9:01 UTC (permalink / raw)
To: Tom de Vries; +Cc: Simon Marchi, gdb-patches
Tom de Vries <tdevries@suse.de> writes:
> On 5/3/23 20:47, Simon Marchi wrote:
>
>> In any case, this LGTM, thanks for doing this.
Seconded, thanks for getting rid of that if guard. I find the new state
of affairs (everything defined in the same unit, in the correct order)
easier to grok.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] [gdb/build] Fix frame_list position in frame.c
2023-05-04 9:01 ` Kévin Le Gouguec
@ 2023-05-04 9:12 ` Tom de Vries
0 siblings, 0 replies; 5+ messages in thread
From: Tom de Vries @ 2023-05-04 9:12 UTC (permalink / raw)
To: Kévin Le Gouguec; +Cc: Simon Marchi, gdb-patches
On 5/4/23 11:01, Kévin Le Gouguec wrote:
> Tom de Vries <tdevries@suse.de> writes:
>
>> On 5/3/23 20:47, Simon Marchi wrote:
>>
>>> In any case, this LGTM, thanks for doing this.
>
> Seconded, thanks for getting rid of that if guard. I find the new state
> of affairs (everything defined in the same unit, in the correct order)
> easier to grok.
Hi Kévin,
thanks for the review and the confirmation.
- Tom
^ permalink raw reply [flat|nested] 5+ messages in thread
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2023-05-03 17:58 [PATCH] [gdb/build] Fix frame_list position in frame.c Tom de Vries
2023-05-03 18:47 ` Simon Marchi
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2023-05-04 9:01 ` Kévin Le Gouguec
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