linux_nat.c: Mark new thread running even if momentarily pausing
Commit Message
My all-stop-on-top-of-non-stop series manages to trip on a bug in the
linux-nat.c backend while running the testsuite. If a thread is
discovered while threads are being momentarily paused (without the
core's intervention), the thread ends up stuck in THREAD_STOPPED
state, even though from the user's perspective, the thread is running
even while it is paused.
From inspection, in the current sources, this can happen if we call
stop_and_resume_callback, though there's no way to test that with
current Linux kernels.
(While trying to come up with test to exercise this, I stumbled on:
https://sourceware.org/ml/gdb-patches/2015-03/msg00850.html
... which does include a non-trivial test, so I think I can still
claim I come out net positive. :-) )
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-03-26 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_handle_extended_wait): Always call set_running.
---
gdb/linux-nat.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
Comments
On 03/26/2015 01:32 PM, Pedro Alves wrote:
> My all-stop-on-top-of-non-stop series manages to trip on a bug in the
> linux-nat.c backend while running the testsuite. If a thread is
> discovered while threads are being momentarily paused (without the
> core's intervention), the thread ends up stuck in THREAD_STOPPED
> state, even though from the user's perspective, the thread is running
> even while it is paused.
>
> From inspection, in the current sources, this can happen if we call
> stop_and_resume_callback, though there's no way to test that with
> current Linux kernels.
>
> (While trying to come up with test to exercise this, I stumbled on:
> https://sourceware.org/ml/gdb-patches/2015-03/msg00850.html
>
> ... which does include a non-trivial test, so I think I can still
> claim I come out net positive. :-) )
>
> Tested on x86_64 Fedora 20.
>
> gdb/ChangeLog:
> 2015-03-26 Pedro Alves <palves@redhat.com>
>
> * linux-nat.c (linux_handle_extended_wait): Always call set_running.
Pushed.
Thanks,
Pedro Alves
@@ -2109,9 +2109,12 @@ linux_handle_extended_wait (struct lwp_info *lp, int status,
add_thread (new_lp->ptid);
}
+ /* Even if we're stopping the thread for some reason
+ internal to this module, from the user/frontend's
+ perspective, this new thread is running. */
+ set_running (new_lp->ptid, 1);
if (!stopping)
{
- set_running (new_lp->ptid, 1);
set_executing (new_lp->ptid, 1);
/* thread_db_attach_lwp -> lin_lwp_attach_lwp forced
resume_stop. */