From: Pedro Alves <pedro@palves.net>
To: Simon Marchi <simark@simark.ca>, gdb-patches@sourceware.org
Subject: Re: [PATCH v2 18/29] gdb: clear step over information on thread exit (PR gdb/27338)
Date: Mon, 12 Dec 2022 20:18:22 +0000 [thread overview]
Message-ID: <ab71b0ac-fcbc-e5ab-533f-6141247208f1@palves.net> (raw)
In-Reply-To: <022c35c9-0e85-b094-a3bc-417feb203894@simark.ca>
On 2022-07-21 7:12 p.m., Simon Marchi wrote:
>> @@ -5428,6 +5443,117 @@ handle_no_resumed (struct execution_control_state *ecs)
>> return false;
>> }
>>
>> +/* Handle a TARGET_WAITKIND_THREAD_EXITED event. Return true if we
>> + handled the event and should continue waiting. Return false if we
>> + should stop and report the event to the user. */
>> +
>> +static bool
>> +handle_thread_exited (execution_control_state *ecs)
>> +{
>> + context_switch (ecs);
>> +
>> + /* Clear these so we don't re-start the thread stepping over a
>> + breakpoint/watchpoint. */
>> + ecs->event_thread->stepping_over_breakpoint = 0;
>> + ecs->event_thread->stepping_over_watchpoint = 0;
>> +
>> + /* Maybe the thread was doing a step-over, if so release
>> + resources and start any further pending step-overs.
>> +
>> + If we are on a non-stop target and the thread was doing an
>> + in-line step, this also restarts the other threads. */
>> + int ret = finish_step_over (ecs);
>> +
>> + /* finish_step_over returns true if it moves ecs' wait status
>> + back into the thread, so that we go handle another pending
>> + event before this one. But we know it never does that if
>> + the event thread has exited. */
>> + gdb_assert (ret == 0);
>> +
>> + /* If finish_step_over started a new in-line step-over, don't
>> + try to restart anything else. */
>> + if (step_over_info_valid_p ())
>> + {
>> + delete_thread (ecs->event_thread);
>> + return true;
>> + }
>> +
>> + /* Maybe we are on an all-stop target and we got this event
>> + while doing a step-like command on another thread. If so,
>> + go back to doing that. If this thread was stepping,
>> + switch_back_to_stepped_thread will consider that the thread
>> + was interrupted mid-step and will try keep stepping it. We
>> + don't want that, the thread is gone. So clear the proceed
>> + status so it doesn't do that. */
>> + clear_proceed_status_thread (ecs->event_thread);
>> + if (switch_back_to_stepped_thread (ecs))
>> + {
>> + delete_thread (ecs->event_thread);
>> + return true;
>> + }
>> +
>> + inferior *inf = ecs->event_thread->inf;
>> + bool slock_applies = schedlock_applies (ecs->event_thread);
>> +
>> + delete_thread (ecs->event_thread);
>> + ecs->event_thread = nullptr;
>> +
>> + auto handle_as_no_resumed = [ecs] ()
>> + {
>> + ecs->ws.set_no_resumed ();
>> + ecs->event_thread = nullptr;
>> + ecs->ptid = minus_one_ptid;
>> + return handle_no_resumed (ecs);
>> + };
>
> Is it really necessary to change the nature of the event?
> handle_no_resumed doesn't seem to actually care about the kind in `ecs`,
> so maybe you could just pass `ecs` down as-is? I think it adds a layer
> of complexity if the ecs gets modified as we handle it, it's simpler to
> follow if it's immutable (other than filling in not-yet-set fields).
>
> But the difficulty I see is that normal_stop does some things when there
> are no resumed threads left. The check there would become a bit more
> complex.
Right, this is more about normal_stop, and how to communicate
"this is a thread exit, but treat it really as a no-resumed event"
down to normal_stop and whatever other spots that would need it.
It's much simpler to just switch the event. Then you know nothing
would miss it.
I moved the set_last_target_status inside the lambda above, so it's all
more together, and added a comment. It was this seemingly-obvious
change that revealed the need for this other series, though:
[PATCH 0/6] Eliminate infrun_thread_thread_exit observer
https://inbox.sourceware.org/gdb-patches/20221203211338.2264994-1-pedro@palves.net/T/#t
>
>> diff --git a/gdb/thread.c b/gdb/thread.c
>> index 6ea05f70a41..a83db6b07fd 100644
>> --- a/gdb/thread.c
>> +++ b/gdb/thread.c
>> @@ -401,6 +401,8 @@ thread_info::clear_pending_waitstatus ()
>> void
>> thread_info::set_thread_options (gdb_thread_options thread_options)
>> {
>> + gdb_assert (this->state != THREAD_EXITED && !this->executing ());
>
> I'd suggesting splitting this in two asserts.
>
Done.
next prev parent reply other threads:[~2022-12-12 20:18 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-13 22:24 [PATCH v2 00/29] Step over thread clone and thread exit Pedro Alves
2022-07-13 22:24 ` [PATCH v2 01/29] displaced step: pass down target_waitstatus instead of gdb_signal Pedro Alves
2022-07-20 20:21 ` Simon Marchi
2022-07-13 22:24 ` [PATCH v2 02/29] linux-nat: introduce pending_status_str Pedro Alves
2022-07-20 20:38 ` Simon Marchi
2022-07-13 22:24 ` [PATCH v2 03/29] gdb/linux: Delete all other LWPs immediately on ptrace exec event Pedro Alves
2022-07-21 0:45 ` Simon Marchi
2022-07-13 22:24 ` [PATCH v2 04/29] Step over clone syscall w/ breakpoint, TARGET_WAITKIND_THREAD_CLONED Pedro Alves
2022-07-21 1:35 ` Simon Marchi
2022-10-17 18:54 ` Pedro Alves
2022-10-18 12:40 ` [PATCH] Don't explicitly set clone child ptrace options (was: Re: [PATCH v2 04/29] Step over clone syscall w/ breakpoint, TARGET_WAITKIND_THREAD_CLONED) Pedro Alves
2022-10-28 14:50 ` Simon Marchi
2022-12-12 20:13 ` [PATCH v2 04/29] Step over clone syscall w/ breakpoint, TARGET_WAITKIND_THREAD_CLONED Pedro Alves
2022-07-13 22:24 ` [PATCH v2 05/29] Support clone events in the remote protocol Pedro Alves
2022-07-21 2:25 ` Simon Marchi
2022-12-12 20:14 ` Pedro Alves
2022-07-13 22:24 ` [PATCH v2 06/29] Avoid duplicate QThreadEvents packets Pedro Alves
2022-07-21 2:30 ` Simon Marchi
2022-12-12 20:14 ` Pedro Alves
2022-07-13 22:24 ` [PATCH v2 07/29] Thread options & clone events (core + remote) Pedro Alves
2022-07-21 3:14 ` Simon Marchi
2022-10-27 19:55 ` [PATCH] enum_flags to_string (was: Re: [PATCH v2 07/29] Thread options & clone events (core + remote)) Pedro Alves
2022-10-28 10:26 ` [PATCH v2] " Pedro Alves
2022-10-28 11:08 ` [PATCH v3] " Pedro Alves
2022-10-28 15:59 ` Simon Marchi
2022-10-28 18:23 ` Pedro Alves
2022-10-31 12:47 ` Simon Marchi
2022-11-07 17:26 ` [PATCH v5] " Pedro Alves
2022-11-07 18:29 ` Simon Marchi
2022-11-08 14:56 ` Pedro Alves
2022-12-12 20:15 ` [PATCH v2 07/29] Thread options & clone events (core + remote) Pedro Alves
2022-07-13 22:24 ` [PATCH v2 08/29] Thread options & clone events (native Linux) Pedro Alves
2022-07-21 12:38 ` Simon Marchi
2022-12-12 20:16 ` Pedro Alves
2022-07-13 22:24 ` [PATCH v2 09/29] Thread options & clone events (Linux GDBserver) Pedro Alves
2022-07-21 13:11 ` Simon Marchi
2022-12-12 20:16 ` Pedro Alves
2022-07-13 22:24 ` [PATCH v2 10/29] gdbserver: Hide and don't detach pending clone children Pedro Alves
2022-07-13 22:24 ` [PATCH v2 11/29] Remove gdb/19675 kfails (displaced stepping + clone) Pedro Alves
2022-07-13 22:24 ` [PATCH v2 12/29] Add test for stepping over clone syscall Pedro Alves
2022-07-13 22:24 ` [PATCH v2 13/29] all-stop/synchronous RSP support thread-exit events Pedro Alves
2022-07-13 22:24 ` [PATCH v2 14/29] gdbserver/linux-low.cc: Ignore event_ptid if TARGET_WAITKIND_IGNORE Pedro Alves
2022-07-13 22:24 ` [PATCH v2 15/29] Introduce GDB_TO_EXIT thread option, fix step-over-thread-exit Pedro Alves
2022-07-13 22:24 ` [PATCH v2 16/29] Implement GDB_TO_EXIT support for Linux GDBserver Pedro Alves
2022-07-13 22:24 ` [PATCH v2 17/29] Implement GDB_TO_EXIT support for native Linux Pedro Alves
2022-07-21 15:26 ` Simon Marchi
2022-12-12 20:17 ` Pedro Alves
2022-07-13 22:24 ` [PATCH v2 18/29] gdb: clear step over information on thread exit (PR gdb/27338) Pedro Alves
2022-07-21 18:12 ` Simon Marchi
2022-12-12 20:18 ` Pedro Alves [this message]
2022-07-13 22:24 ` [PATCH v2 19/29] stop_all_threads: (re-)enable async before waiting for stops Pedro Alves
2022-07-21 18:21 ` Simon Marchi
2022-12-12 20:18 ` Pedro Alves
2022-07-13 22:24 ` [PATCH v2 20/29] gdbserver: Queue no-resumed event after thread exit Pedro Alves
2022-07-13 22:24 ` [PATCH v2 21/29] Don't resume new threads if scheduler-locking is in effect Pedro Alves
2022-07-14 5:28 ` Eli Zaretskii
2022-07-21 18:49 ` Simon Marchi
2022-12-12 20:19 ` Pedro Alves
2022-07-13 22:24 ` [PATCH v2 22/29] Report thread exit event for leader if reporting thread exit events Pedro Alves
2022-07-13 22:24 ` [PATCH v2 23/29] Ignore failure to read PC when resuming Pedro Alves
2022-07-13 22:24 ` [PATCH v2 24/29] gdb/testsuite/lib/my-syscalls.S: Refactor new SYSCALL macro Pedro Alves
2022-07-13 22:24 ` [PATCH v2 25/29] Testcases for stepping over thread exit syscall (PR gdb/27338) Pedro Alves
2022-07-13 22:24 ` [PATCH v2 26/29] Document remote clone events, and QThreadOptions packet Pedro Alves
2022-07-14 5:27 ` Eli Zaretskii
2022-07-13 22:24 ` [PATCH v2 27/29] inferior::clear_thread_list always silent Pedro Alves
2022-07-13 22:24 ` [PATCH v2 28/29] Centralize "[Thread ...exited]" notifications Pedro Alves
2022-07-13 22:24 ` [PATCH v2 29/29] Cancel execution command on thread exit, when stepping, nexting, etc Pedro Alves
2022-07-21 19:28 ` [PATCH v2 00/29] Step over thread clone and thread exit Simon Marchi
2022-10-03 13:46 ` Tom de Vries
2022-10-03 18:37 ` Tom de Vries
2022-12-12 20:20 ` Pedro Alves
2022-12-12 20:19 ` Pedro Alves
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