Re: [PATCH 2/4] Push pruning old threads down to the target

Thomas Schwinge
2016-12-09T06:38:21Z

Hi!

On Thu, 2 Oct 2014 17:21:34 +0100, Pedro Alves <palves@redhat.com> wrote:
> When GDB wants to sync the thread list with the target's [...]

> --- a/gdb/thread.c
> +++ b/gdb/thread.c

> void
> update_thread_list (void)
> {
> - prune_threads ();
> - target_find_new_threads ();
> + target_update_thread_list ();
> update_threads_executing ();
> }

Pushed to master:

commit c752a4cccb99ba73f51eff74b394dcdcd26d4c59
Author: Thomas Schwinge <thomas@codesourcery.com>
Date: Wed May 25 18:54:40 2016 +0200

Hurd: Adjust to changes to "push pruning old threads down to the target"

For "info threads", we currently run into:

$ gdb/gdb -q -nw -nx --batch -ex start -ex info\ threads bfd/doc/chew
Temporary breakpoint 1 at 0x80486e0: file ../../../W._C._Handy/bfd/doc/chew.c, line 1535.
[New Thread 10656.5]

Thread 4 hit Temporary breakpoint 1, main (ac=1, av=0x102cd84) at ../../../W._C._Handy/bfd/doc/chew.c:1535
1535 {
Id Target Id Frame
1 bogus thread id 1 Can't fetch registers from thread bogus thread id 1: No such thread

Before commit e8032dde10b743253125d7defb5f5503b21c1d26,
gdb/thread.c:update_thread_list used to call prune_threads, after that change
it doesn't anymore, and we don't implement the to_update_thread_list target
method where the prune_threads call got moved. For now, apply a fix, related
to commit c82f56d9d760a9b4034eeaac44f2f0fa5779ff69 "Hurd: Adjust to
startup-with-shell changes", which restores the previous behavior:

Id Target Id Frame
* 4 Thread 10688.4 main (ac=1, av=0x102cd84) at ../../../W._C._Handy/bfd/doc/chew.c:1535
5 Thread 10688.5 0x0106096c in ?? () from /lib/i386-gnu/libc.so.0.3

Not perfect, but at least better.

gdb/
* gnu-nat.c (gnu_create_inferior): After startup_inferior, call
prune_threads.
---
gdb/ChangeLog | 3 +++
gdb/gnu-nat.c | 2 ++
2 files changed, 5 insertions(+)

diff --git gdb/ChangeLog gdb/ChangeLog
index 302eb6e..7fd5d32 100644
--- gdb/ChangeLog
+++ gdb/ChangeLog
@@ -1,5 +1,8 @@
2016-12-09 Thomas Schwinge <thomas@codesourcery.com>

+ * gnu-nat.c (gnu_create_inferior): After startup_inferior, call
+ prune_threads.
+
* inferior.c (print_selected_inferior): Avoid PATH_MAX usage.

2016-12-08 Simon Marchi <simon.marchi@ericsson.com>
diff --git gdb/gnu-nat.c gdb/gnu-nat.c
index 124574e..85a53b8 100644
--- gdb/gnu-nat.c
+++ gdb/gnu-nat.c
@@ -2163,6 +2163,8 @@ gnu_create_inferior (struct target_ops *ops,

startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
inf->pending_execs = 0;
+ /* Get rid of the old shell threads. */
+ prune_threads ();

inf_validate_procinfo (inf);
inf_update_signal_thread (inf);

Grüße
Thomas