From: Simon Marchi <simark@simark.ca>
To: Pedro Alves <palves@redhat.com>, gdb-patches@sourceware.org
Subject: Re: [PATCH v2 18/24] Multi-target support
Date: Fri, 17 Jan 2020 16:19:00 -0000 [thread overview]
Message-ID: <0efdd157-43cc-62ba-1d8e-ae444db59b43@simark.ca> (raw)
In-Reply-To: <c17d429d-452d-557d-377d-b7f1bd9bf269@simark.ca>
On 2020-01-16 10:47 p.m., Simon Marchi wrote:
> On 2019-10-17 6:50 p.m., Pedro Alves wrote:
>> This commit adds multi-target support to GDB. What this means is that
>> with this commit, GDB can now be connected to different targets at the
>> same time. E.g., you can debug a live native process and a core dump
>> at the same time, connect to multiple gdbservers, etc.
>
> Hi Pedro,
>
> I think I found something odd happening starting with this commit. When
> the test gdb.threads/tid-reuse.exp runs, we are adding a thread_info to the
> inferior's thread list when a thread_info object with the same ptid is
> already present. I don't think this is ever supposed to happen, right?
>
> This can be observed by applying the following diff and running
> gdb.threads/tid-reuse.exp. Note that some distributions are starting to bump
> pid_max to a really large value, so make sure it's not that on your system.
>
> diff --git a/gdb/thread.c b/gdb/thread.c
> index 4959f938c7f3..8909e371e2ce 100644
> --- a/gdb/thread.c
> +++ b/gdb/thread.c
> @@ -254,7 +254,10 @@ new_thread (struct inferior *inf, ptid_t ptid)
> struct thread_info *last;
>
> for (last = inf->thread_list; last->next != NULL; last = last->next)
> - ;
> + gdb_assert (ptid != last->ptid);
> +
> + gdb_assert (ptid != last->ptid);
> +
> last->next = tp;
> }
>
>
> What I have found so far, by breaking at thread.c:274 and stepping into
> the "delete_thread" call, is that `inferior_ptid == ptid` is false
> (inferior_ptid is (0,0,0)). In delete_thread, we are actually not
> deleting the thread because ->deletable () returns false, because
> the refcount is 2.
>
> Before this patch, we would enter the `if (inferior_ptid == ptid)`.
>
> If it can help, here is the command line I'm using to debug this, which is
> mimicking the test:
>
> ./gdb -nx --data-directory=data-directory testsuite/outputs/gdb.threads/tid-reuse/tid-reuse -iex "set confirm off" -iex "set pagination off" -ex start -ex "set print thread-events off" -ex "b after_count" -ex c -ex "b do_nothing_thread_func" -ex c -ex d -ex "b after_reuse_time" -ex c
>
> Simon
>
I filed this in bugzilla, so we can track it better:
https://sourceware.org/bugzilla/show_bug.cgi?id=25412
Simon
next prev parent reply other threads:[~2020-01-17 15:49 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-17 22:50 [PATCH v2 00/24] " Pedro Alves
2019-10-17 22:50 ` [PATCH v2 10/24] Some get_last_target_status tweaks Pedro Alves
2019-10-17 22:50 ` [PATCH v2 03/24] Make "show remote exec-file" inferior-aware Pedro Alves
2019-10-17 22:50 ` [PATCH v2 11/24] tfile_target::close: trace_fd can't be -1 Pedro Alves
2019-10-17 22:50 ` [PATCH v2 01/24] Preserve selected thread in all-stop w/ background execution Pedro Alves
2019-11-01 13:20 ` Tom Tromey
2019-12-20 17:22 ` Pedro Alves
2019-12-20 18:54 ` Tom Tromey
2019-12-20 18:57 ` Pedro Alves
2019-12-20 18:57 ` Tom Tromey
2019-10-17 22:50 ` [PATCH v2 09/24] switch inferior/thread before calling target methods Pedro Alves
2019-10-17 22:50 ` [PATCH v2 21/24] Revert 'Remove unused struct serial::name field' Pedro Alves
2019-10-17 22:50 ` [PATCH v2 15/24] Avoid another inferior_ptid reference in gdb/remote.c Pedro Alves
2019-10-17 22:50 ` [PATCH v2 06/24] Don't check target is running in remote_target::mourn_inferior Pedro Alves
2019-10-17 22:50 ` [PATCH v2 16/24] Fix reconnecting to a gdbserver already debugging multiple processes, I Pedro Alves
2019-10-17 22:50 ` [PATCH v2 17/24] Fix reconnecting to a gdbserver already debugging multiple processes, II Pedro Alves
2019-10-17 22:50 ` [PATCH v2 02/24] Don't rely on inferior_ptid in record_full_wait Pedro Alves
2019-11-01 14:54 ` Tom Tromey
2019-12-20 17:49 ` Pedro Alves
2019-12-20 18:57 ` Tom Tromey
2019-10-17 22:50 ` [PATCH v2 12/24] Use all_non_exited_inferiors in infrun.c Pedro Alves
2019-10-17 22:51 ` [PATCH v2 19/24] Add multi-target tests Pedro Alves
2019-10-17 22:51 ` [PATCH v2 18/24] Multi-target support Pedro Alves
2020-01-11 3:12 ` Simon Marchi
2020-01-12 1:58 ` [pushed] Remove last traces of discard_all_inferiors (Re: [PATCH v2 18/24] Multi-target support) Pedro Alves
2020-01-12 20:17 ` [PATCH v2 18/24] Multi-target support Simon Marchi
2020-01-13 15:19 ` Pedro Alves
2020-01-13 16:37 ` Simon Marchi
2020-01-12 22:30 ` Simon Marchi
2020-01-13 15:59 ` Pedro Alves
2020-01-17 4:03 ` Simon Marchi
2020-01-17 16:19 ` Simon Marchi [this message]
2020-01-17 15:18 ` Simon Marchi
2020-05-16 8:16 ` Andreas Schwab
2020-05-16 11:33 ` Fix IA-64 GNU/Linux build (Re: [PATCH v2 18/24] Multi-target support) Pedro Alves
2019-10-17 22:51 ` [PATCH v2 04/24] exceptions.c:print_flush: Remove obsolete check Pedro Alves
2019-10-17 22:51 ` [PATCH v2 22/24] Add "info connections" command, "info inferiors" connection number/string Pedro Alves
2019-10-17 22:57 ` [PATCH v2 23/24] Require always-non-stop for multi-target resumptions Pedro Alves
2019-11-01 14:51 ` Tom Tromey
2019-12-30 18:30 ` Pedro Alves
2019-12-31 20:06 ` Tom Tromey
2019-10-17 22:57 ` [PATCH v2 07/24] Delete unnecessary code from kill_command Pedro Alves
2019-10-17 22:57 ` [PATCH v2 05/24] Make target_ops::has_execution take an 'inferior *' instead of a ptid_t Pedro Alves
2019-10-17 22:59 ` [PATCH v2 13/24] Delete exit_inferior_silent(int pid) Pedro Alves
2019-10-17 22:59 ` [PATCH v2 20/24] gdbarch-selftests.c: No longer error out if debugging something Pedro Alves
2019-10-17 22:59 ` [PATCH v2 08/24] Introduce switch_to_inferior_no_thread Pedro Alves
2019-11-07 9:14 ` Paunovic, Aleksandar
2019-12-20 18:50 ` Pedro Alves
2019-12-23 19:30 ` [PATCH] Switch the inferior too in switch_to_program_space_and_thread (Re: [PATCH v2 08/24] Introduce switch_to_inferior_no_thread) Pedro Alves
2020-01-08 15:48 ` Aktemur, Tankut Baris
2020-01-10 2:03 ` Pedro Alves
2020-01-10 11:33 ` Aktemur, Tankut Baris
2020-01-10 12:18 ` Pedro Alves
2020-01-10 13:51 ` Aktemur, Tankut Baris
2020-01-10 14:41 ` Tom Tromey
2020-01-10 20:03 ` Pedro Alves
2019-10-17 22:59 ` [PATCH v2 24/24] Multi-target: NEWS and user manual Pedro Alves
2019-10-17 23:00 ` [PATCH v2 14/24] Tweak handling of remote errors in response to resumption packet Pedro Alves
2019-10-18 20:23 ` [PATCH v2 00/24] Multi-target support John Baldwin
2019-10-29 19:13 ` Pedro Alves
2020-01-09 19:32 ` John Baldwin
2020-01-09 19:50 ` Pedro Alves
2020-01-10 13:49 ` Aktemur, Tankut Baris
2020-01-10 15:40 ` [PATCH] Switch the inferior before outputting its id in "info inferiors" (Re: [PATCH v2 00/24] Multi-target support) Pedro Alves
2019-10-20 11:41 ` [PATCH v2 00/24] Multi-target support Philippe Waroquiers
2019-10-29 19:56 ` Pedro Alves
2019-11-01 14:56 ` Tom Tromey
2020-01-10 20:13 ` Pedro Alves
2020-08-04 3:30 ` Kevin Buettner
2020-08-06 15:16 ` Pedro Alves
2020-08-06 17:49 ` Tom Tromey
2020-08-07 22:43 ` Kevin Buettner
2020-08-12 18:45 ` Pedro Alves
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