From: John Baldwin <jhb@FreeBSD.org>
To: Pedro Alves <palves@redhat.com>, gdb-patches@sourceware.org
Subject: Re: Multiprocess on FreeBSD
Date: Tue, 7 Jul 2020 17:34:05 -0700 [thread overview]
Message-ID: <36435498-0c12-7e2b-3bbe-8e965ce7c80b@FreeBSD.org> (raw)
In-Reply-To: <b4b3af1e-b41d-1518-d9dc-b035ce71f13d@FreeBSD.org>
On 7/7/20 5:10 PM, John Baldwin wrote:
> On 7/7/20 4:16 PM, John Baldwin wrote:
>> FNAT: stop for LWP 101641 event 1 flags 0x18
>> FLWP: fbsd_resume for ptid (70453, 101518, 0)
>>
>> Program terminated with signal SIGTRAP, Trace/breakpoint trap.
>> The program no longer exists.
>>
>> Here you can see that the last call to fbsd_resume() used the ptid from
>> inferior 1 instead of inferior 2, and inferior 1 didn't discard it's
>> pending SIGTRAP but instead was killed by it.)
>
> On this part, I turned on 'set debug infrun 1' and can see that
> the core is trying to step over the breakpoint in the first
> inferior. However, it is not clearing the SIGTRAP signal to
> GDB_SIGNAL_0 when resuming the first inferior but leaving it as
> GDB_SIGNAL_TRAP. This appears to be because start_step_over()
> calls keep_going_pass_signal() instead of keep_going(), so
> tp->control.stop_signal doesn't get reset. I'm not sure if
> stop_signal should have been cleared earlier somehow?
>
> Hmm, if I add a hack to ignore SIGTRAP in fbsd_nat_target::resume(),
> then what happens is that the first inferior runs to completion.
> I can run the second inferior after switching to it, but I think the
> behavior I probably want is for the core to not resume threads from
> the non-current inferior instead?
>
> One last test I tried is to do this sequence instead in the first
> inferior:
>
> (gdb) file /bin/ls
> (gdb) start
> (gdb) n
>
> This gets the first inferior off of the breakpoint and the thread is
> stopped for a hardware stepping trap instead.
>
> I can then add an inferior do start and have it work fine, and I
> can switch back and forth between the two inferiors stepping each
> one.
>
> So I think the issue here is that for some reason when the 'start'
> command for inferior 2 tries to resume the inferior after getting
> across the initial events for exec, it ends up resuming the wrong
> inferior due to confusion about the thread stopped at a breakpoint.
> However, it doesn't get confused if the thread is stopped for some
> other reason.
I had to add a 'fbsd_nat_target::supports_multi_process' method and
now it seems to work fine.
It does depend on the fix to use find_inferior_pid() to work.
--
John Baldwin
prev parent reply other threads:[~2020-07-08 0:35 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 17:54 [PATCH 00/28] Decouple inferior_ptid/inferior_thread(); dup ptids in thread list (PR/25412) Pedro Alves
2020-04-14 17:54 ` [PATCH 01/28] Don't write to inferior_ptid in linux_get_siginfo_data Pedro Alves
2020-04-14 17:54 ` [PATCH 02/28] gcore, handle exited threads better Pedro Alves
2020-04-14 17:54 ` [PATCH 03/28] Refactor delete_program_space as a destructor Pedro Alves
2020-04-15 15:54 ` Simon Marchi
2020-04-16 14:47 ` Pedro Alves
2020-04-14 17:54 ` [PATCH 04/28] Don't write to inferior_ptid in gdbarch-selftests.c, mock address_space too Pedro Alves
2020-04-14 17:54 ` [PATCH 05/28] Don't write to inferior_ptid in inf-ptrace.c Pedro Alves
2020-04-14 17:54 ` [PATCH 06/28] Don't write to inferior_ptid in target.c Pedro Alves
2020-04-14 17:54 ` [PATCH 07/28] Don't write to inferior_ptid in infrun.c Pedro Alves
2020-04-14 17:54 ` [PATCH 08/28] Don't write to inferior_ptid in procfs.c Pedro Alves
2020-04-14 17:54 ` [PATCH 09/28] Don't write to inferior_ptid in tracefile-tfile.c Pedro Alves
2020-04-14 17:54 ` [PATCH 10/28] Don't write to inferior_ptid in tracectf.c Pedro Alves
2020-04-14 17:54 ` [PATCH 11/28] Don't write to inferior_ptid in remote.c Pedro Alves
2020-04-14 17:54 ` [PATCH 12/28] Don't write to inferior_ptid in remote-sim.c Pedro Alves
2020-04-14 17:54 ` [PATCH 13/28] Don't write to inferior_ptid in nto-procfs.c Pedro Alves
2020-04-14 17:54 ` [PATCH 14/28] Don't write to inferior_ptid in go32-nat.c Pedro Alves
2020-04-14 17:54 ` [PATCH 15/28] Don't write to inferior_ptid in gnu-nat.c Pedro Alves
2020-04-14 17:54 ` [PATCH 16/28] Don't write to inferior_ptid in darwin-nat.c Pedro Alves
2020-04-16 1:33 ` Simon Marchi
2020-04-16 19:23 ` Pedro Alves
2020-04-14 17:54 ` [PATCH 17/28] Don't write to inferior_ptid in corelow.c Pedro Alves
2020-04-14 17:54 ` [PATCH 18/28] Don't write to inferior_ptid in bsd-kvm.c Pedro Alves
2020-04-14 17:54 ` [PATCH 19/28] Don't write to inferior_ptid in btrace_fetch Pedro Alves
2020-04-15 4:52 ` Metzger, Markus T
2020-04-15 14:13 ` Pedro Alves
2020-04-15 15:17 ` Metzger, Markus T
2020-04-14 17:54 ` [PATCH 20/28] Don't write to inferior_ptid in bsd-kvm.c Pedro Alves
2020-04-14 17:54 ` [PATCH 21/28] Don't write to inferior_ptid in fork-child.c Pedro Alves
2020-04-14 17:54 ` [PATCH 22/28] Don't write to inferior_ptid in go32-nat.c Pedro Alves
2020-04-14 17:54 ` [PATCH 23/28] Don't write to inferior_ptid in remote-sim.c Pedro Alves
2020-04-16 0:53 ` Simon Marchi
2020-04-16 14:58 ` Pedro Alves
2020-04-14 17:54 ` [PATCH 24/28] Don't write to inferior_ptid in windows-nat.c, part I Pedro Alves
2020-04-14 17:54 ` [PATCH 25/28] Don't write to inferior_ptid in windows-nat.c, part II Pedro Alves
2020-04-14 22:41 ` Hannes Domani
2020-04-15 15:08 ` Pedro Alves
2020-04-15 15:32 ` Hannes Domani
2020-04-14 17:54 ` [PATCH 26/28] Don't write to inferior_ptid in ravenscar-thread.c Pedro Alves
2020-04-17 18:45 ` Tom Tromey
2020-06-18 20:00 ` Pedro Alves
2020-06-18 21:38 ` Tom Tromey
2020-04-14 17:54 ` [PATCH 27/28] Don't write to inferior_ptid in aix-thread.c Pedro Alves
2020-04-14 17:54 ` [PATCH 28/28] Decouple inferior_ptid/inferior_thread(); dup ptids in thread list (PR/25412) Pedro Alves
2020-04-16 19:39 ` Simon Marchi
2020-04-16 20:12 ` Pedro Alves
2020-04-16 20:38 ` Simon Marchi
2020-04-17 10:29 ` Pedro Alves
2020-04-17 14:06 ` Simon Marchi
2020-04-17 16:46 ` Pedro Alves
2020-04-17 18:53 ` Tom Tromey
2020-06-18 19:59 ` Pedro Alves
2020-06-23 13:37 ` Andrew Burgess
2020-06-23 14:26 ` Pedro Alves
2020-06-23 15:38 ` [PATCH] Fix "maint selftest" regression, add struct, scoped_mock_context Pedro Alves
2020-06-23 16:34 ` Andrew Burgess
2020-06-23 17:58 ` Pedro Alves
2020-04-14 18:46 ` [PATCH 00/28] Decouple inferior_ptid/inferior_thread(); dup ptids in thread list (PR/25412) Hannes Domani
2020-04-14 19:24 ` Pedro Alves
2020-04-15 15:04 ` Simon Marchi
2020-04-16 13:41 ` Pedro Alves
2020-04-15 14:46 ` Simon Marchi
2020-04-15 15:33 ` Pedro Alves
2020-04-15 15:42 ` Simon Marchi
2020-04-17 20:20 ` Tom Tromey
2020-06-18 20:00 ` Pedro Alves
2020-06-18 22:30 ` Pedro Alves
2020-07-07 23:16 ` John Baldwin
2020-07-07 23:53 ` Pedro Alves
2020-07-08 0:19 ` John Baldwin
2020-07-08 0:10 ` Multiprocess on FreeBSD John Baldwin
2020-07-08 0:34 ` John Baldwin [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=36435498-0c12-7e2b-3bbe-8e965ce7c80b@FreeBSD.org \
--to=jhb@freebsd.org \
--cc=gdb-patches@sourceware.org \
--cc=palves@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).