Re: [downstream patch FYI] workaround stale frame_info * (PR 13866)

Pedro Alves
2012-06-05T19:24:34Z

On 04/04/2012 08:14 PM, Jan Kratochvil wrote:

>
> Reproducer with:
> ./gdb -nx ~/t/thread -ex 'b 24' -ex r -ex 'until 25'
> Breakpoint 1, main () at /home/jkratoch/t/thread.c:24
> 24 v++;
> Segmentation fault (core dumped)
>
> #include <pthread.h>
> #include <assert.h>
> #include <unistd.h>
>
> static int v;
>
> static void *start (void *arg)
> {
> v++;
> v++;
> v++;
> v++;
> sleep (100);
> return arg;
> }
>
> int main (void)
> {
> pthread_t thread1;
> int i;
>
> i = pthread_create (&thread1, NULL, start, NULL);
> assert (i == 0);
> v++;
> v++;
> v++;
> v++;
> i = pthread_join (thread1, NULL);
> assert (i == 0);
>
> return 0;
> }

This fixes the crash.

2012-06-05 Pedro Alves <palves@redhat.com>

PR backtrace/13866

* breakpoint.c (until_break_command): Only fetch the selected
frame after decode_line_1.
---

gdb/breakpoint.c | 13 +++++++++----
1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 5cc1f64..9757d0d 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -10815,10 +10815,10 @@ until_break_command (char *arg, int from_tty, int anywhere)
{
struct symtabs_and_lines sals;
struct symtab_and_line sal;
- struct frame_info *frame = get_selected_frame (NULL);
- struct gdbarch *frame_gdbarch = get_frame_arch (frame);
- struct frame_id stack_frame_id = get_stack_frame_id (frame);
- struct frame_id caller_frame_id = frame_unwind_caller_id (frame);
+ struct frame_info *frame;
+ struct gdbarch *frame_gdbarch;
+ struct frame_id stack_frame_id;
+ struct frame_id caller_frame_id;
struct breakpoint *breakpoint;
struct breakpoint *breakpoint2 = NULL;
struct cleanup *old_chain;
@@ -10854,6 +10854,11 @@ until_break_command (char *arg, int from_tty, int anywhere)

old_chain = make_cleanup (null_cleanup, NULL);

+ frame = get_selected_frame (NULL);
+ frame_gdbarch = get_frame_arch (frame);
+ stack_frame_id = get_stack_frame_id (frame);
+ caller_frame_id = frame_unwind_caller_id (frame);
+
/* Installing a breakpoint invalidates the frame chain (as it may
need to switch threads), so do any frame handling first. */