Re: [PATCH 30/31] Centralize "[Thread ...exited]" notifications

Andrew Burgess via Gdb-patches
2023-02-16T15:40:45Z

Pedro Alves <pedro@palves.net> writes:

> Currently, each target backend is responsible for printing "[Thread
> ...exited]" before deleting a thread. This leads to unnecessary
> differences between targets, like e.g. with the remote target, we
> never print such messages, even though we do print "[New Thread ...]".
>
> E.g., debugging the gdb.threads/attach-many-short-lived-threads.exp
> with gdbserver, letting it run for a bit, and then pressing Ctrl-C, we
> currently see:

I'm currently writing some tests that run into this issue, and I needed
a bug-id to use in the XFAIL messages. I've created PR gdb/30129 for
this issue:

https://sourceware.org/bugzilla/show_bug.cgi?id=30129

Thanks,
Andrew

>
> (gdb) c
> Continuing.
> ^C[New Thread 3850398.3887449]
> [New Thread 3850398.3887500]
> [New Thread 3850398.3887551]
> [New Thread 3850398.3887602]
> [New Thread 3850398.3887653]
> ...
>
> Thread 1 "attach-many-sho" received signal SIGINT, Interrupt.
> 0x00007ffff7e6a23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, req=req@entry=0x7fffffffda80, rem=rem@entry=0x7fffffffda80)
> at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
> 78 in ../sysdeps/unix/sysv/linux/clock_nanosleep.c
> (gdb)
>
> Above, we only see "New Thread" notifications, even though threads
> were deleted.
>
> After this patch, we'll see:
>
> (gdb) c
> Continuing.
> ^C[Thread 3558643.3577053 exited]
> [Thread 3558643.3577104 exited]
> [Thread 3558643.3577155 exited]
> [Thread 3558643.3579603 exited]
> ...
> [New Thread 3558643.3597415]
> [New Thread 3558643.3600015]
> [New Thread 3558643.3599965]
> ...
>
> Thread 1 "attach-many-sho" received signal SIGINT, Interrupt.
> 0x00007ffff7e6a23f in __GI___clock_nanosleep (clock_id=clock_id@entry=0, flags=flags@entry=0, req=req@entry=0x7fffffffda80, rem=rem@entry=0x7fffffffda80)
> at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78
> 78 in ../sysdeps/unix/sysv/linux/clock_nanosleep.c
> (gdb) q
>
>
> This commit fixes this by moving the thread exit printing to common
> code instead, triggered from within delete_thread (or rather,
> set_thread_exited).
>
> There's one wrinkle, though. While most targest want to print:
>
> [Thread ... exited]
>
> the Windows target wants to print:
>
> [Thread ... exited with code <exit_code>]
>
> ... and sometimes wants to suppress the notification for the main
> thread. To address that, this commits adds a delete_thread_with_code
> function, only used by that target (so far).
>
> Change-Id: I06ec07b7c51527872a9713dd11cf7867b50fc5ff
> ---
> gdb/annotate.c | 4 +++-
> gdb/breakpoint.c | 4 +++-
> gdb/fbsd-nat.c | 3 ---
> gdb/gdbthread.h | 22 +++++++++++++----
> gdb/inferior.c | 2 +-
> gdb/inferior.h | 2 ++
> gdb/linux-nat.c | 11 +++------
> gdb/mi/mi-interp.c | 8 +++++--
> gdb/netbsd-nat.c | 4 ----
> gdb/observable.h | 11 +++++----
> gdb/procfs.c | 6 -----
> gdb/python/py-inferior.c | 4 +++-
> gdb/thread.c | 51 ++++++++++++++++++++++++++++++----------
> gdb/windows-nat.c | 16 ++++---------
> 14 files changed, 89 insertions(+), 59 deletions(-)
>
> diff --git a/gdb/annotate.c b/gdb/annotate.c
> index 33805dcdb30..b45384ddb15 100644
> --- a/gdb/annotate.c
> +++ b/gdb/annotate.c
> @@ -233,7 +233,9 @@ annotate_thread_changed (void)
> /* Emit notification on thread exit. */
>
> static void
> -annotate_thread_exited (struct thread_info *t, int silent)
> +annotate_thread_exited (thread_info *t,
> + gdb::optional<ULONGEST> exit_code,
> + bool /* silent */)
> {
> if (annotation_level > 1)
> {
> diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
> index f0276a963c0..0736231e470 100644
> --- a/gdb/breakpoint.c
> +++ b/gdb/breakpoint.c
> @@ -3237,7 +3237,9 @@ remove_breakpoints (void)
> that thread. */
>
> static void
> -remove_threaded_breakpoints (struct thread_info *tp, int silent)
> +remove_threaded_breakpoints (thread_info *tp,
> + gdb::optional<ULONGEST> exit_code,
> + bool /* silent */)
> {
> for (breakpoint *b : all_breakpoints_safe ())
> {
> diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
> index 1aec75050ae..3d1e742f4e3 100644
> --- a/gdb/fbsd-nat.c
> +++ b/gdb/fbsd-nat.c
> @@ -1300,9 +1300,6 @@ fbsd_nat_target::wait_1 (ptid_t ptid, struct target_waitstatus *ourstatus,
> {
> fbsd_lwp_debug_printf ("deleting thread for LWP %u",
> pl.pl_lwpid);
> - if (print_thread_events)
> - gdb_printf (_("[%s exited]\n"),
> - target_pid_to_str (wptid).c_str ());
> low_delete_thread (thr);
> delete_thread (thr);
> }
> diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
> index 43e9d6ea484..7ab02873f17 100644
> --- a/gdb/gdbthread.h
> +++ b/gdb/gdbthread.h
> @@ -636,16 +636,30 @@ extern struct thread_info *add_thread_with_info (process_stratum_target *targ,
>
> /* Delete thread THREAD and notify of thread exit. If the thread is
> currently not deletable, don't actually delete it but still tag it
> - as exited and do the notification. */
> -extern void delete_thread (struct thread_info *thread);
> + as exited and do the notification. EXIT_CODE is the thread's exit
> + code. If SILENT, don't actually notify the CLI. THREAD must not
> + be NULL or an assertion will fail. */
> +extern void delete_thread_with_exit_code (thread_info *thread,
> + ULONGEST exit_code,
> + bool silent = false);
> +
> +/* Delete thread THREAD and notify of thread exit. If the thread is
> + currently not deletable, don't actually delete it but still tag it
> + as exited and do the notification. THREAD must not be NULL or an
> + assertion will fail. */
> +extern void delete_thread (thread_info *thread);
>
> /* Like delete_thread, but be quiet about it. Used when the process
> this thread belonged to has already exited, for example. */
> extern void delete_thread_silent (struct thread_info *thread);
>
> /* Mark the thread exited, but don't delete it or remove it from the
> - inferior thread list. */
> -extern void set_thread_exited (thread_info *tp, bool silent);
> + inferior thread list. EXIT_CODE is the thread's exit code, if
> + available. If SILENT, then don't inform the CLI about the
> + exit. */
> +extern void set_thread_exited (thread_info *tp,
> + gdb::optional<ULONGEST> exit_code = {},
> + bool silent = false);
>
> /* Delete a step_resume_breakpoint from the thread database. */
> extern void delete_step_resume_breakpoint (struct thread_info *);
> diff --git a/gdb/inferior.c b/gdb/inferior.c
> index eacb65ec1d7..834eabdf2ca 100644
> --- a/gdb/inferior.c
> +++ b/gdb/inferior.c
> @@ -174,7 +174,7 @@ inferior::clear_thread_list ()
> {
> threads_debug_printf ("deleting thread %s",
> thr->ptid.to_string ().c_str ());
> - set_thread_exited (thr, true);
> + set_thread_exited (thr, {}, true);
> if (thr->deletable ())
> delete thr;
> });
> diff --git a/gdb/inferior.h b/gdb/inferior.h
> index 07d9527a802..cf3f1275cc1 100644
> --- a/gdb/inferior.h
> +++ b/gdb/inferior.h
> @@ -628,6 +628,8 @@ extern void detach_inferior (inferior *inf);
>
> extern void exit_inferior (inferior *inf);
>
> +/* Like exit_inferior, but be quiet -- don't announce the exit of the
> + inferior's threads to the CLI. */
> extern void exit_inferior_silent (inferior *inf);
>
> extern void exit_inferior_num_silent (int num);
> diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
> index 75f81edf20a..acf5fd3f1b1 100644
> --- a/gdb/linux-nat.c
> +++ b/gdb/linux-nat.c
> @@ -916,15 +916,10 @@ linux_nat_switch_fork (ptid_t new_ptid)
> static void
> exit_lwp (struct lwp_info *lp, bool del_thread = true)
> {
> - struct thread_info *th = find_thread_ptid (linux_target, lp->ptid);
> -
> - if (th)
> + if (del_thread)
> {
> - if (print_thread_events)
> - gdb_printf (_("[%s exited]\n"),
> - target_pid_to_str (lp->ptid).c_str ());
> -
> - if (del_thread)
> + thread_info *th = find_thread_ptid (linux_target, lp->ptid);
> + if (th != nullptr)
> delete_thread (th);
> }
>
> diff --git a/gdb/mi/mi-interp.c b/gdb/mi/mi-interp.c
> index 3cc2462f672..189dd1f302f 100644
> --- a/gdb/mi/mi-interp.c
> +++ b/gdb/mi/mi-interp.c
> @@ -68,7 +68,9 @@ static void mi_on_normal_stop (struct bpstat *bs, int print_frame);
> static void mi_on_no_history (void);
>
> static void mi_new_thread (struct thread_info *t);
> -static void mi_thread_exit (struct thread_info *t, int silent);
> +static void mi_thread_exit (thread_info *t,
> + gdb::optional<ULONGEST> exit_code,
> + bool silent);
> static void mi_record_changed (struct inferior*, int, const char *,
> const char *);
> static void mi_inferior_added (struct inferior *inf);
> @@ -351,8 +353,10 @@ mi_new_thread (struct thread_info *t)
> }
> }
>
> +/* Observer for the thread_exit notification. */
> +
> static void
> -mi_thread_exit (struct thread_info *t, int silent)
> +mi_thread_exit (thread_info *t, gdb::optional<ULONGEST> exit_code, bool silent)
> {
> SWITCH_THRU_ALL_UIS ()
> {
> diff --git a/gdb/netbsd-nat.c b/gdb/netbsd-nat.c
> index aa16a6cc5bd..9674baeb846 100644
> --- a/gdb/netbsd-nat.c
> +++ b/gdb/netbsd-nat.c
> @@ -625,10 +625,6 @@ nbsd_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
> {
> /* NetBSD does not store an LWP exit status. */
> ourstatus->set_thread_exited (0);
> -
> - if (print_thread_events)
> - gdb_printf (_("[%s exited]\n"),
> - target_pid_to_str (wptid).c_str ());
> }
>
> /* The GDB core expects that the rest of the threads are running. */
> diff --git a/gdb/observable.h b/gdb/observable.h
> index 1103c5c98a6..a4ab4f1e38f 100644
> --- a/gdb/observable.h
> +++ b/gdb/observable.h
> @@ -126,10 +126,13 @@ extern observable<struct objfile */* objfile */> free_objfile;
> /* The thread specified by T has been created. */
> extern observable<struct thread_info */* t */> new_thread;
>
> -/* The thread specified by T has exited. The SILENT argument
> - indicates that gdb is removing the thread from its tables without
> - wanting to notify the user about it. */
> -extern observable<struct thread_info */* t */, int /* silent */> thread_exit;
> +/* The thread specified by T has exited. EXIT_CODE is the thread's
> + exit code, if available. The SILENT argument indicates that GDB is
> + removing the thread from its tables without wanting to notify the
> + CLI about it. */
> +extern observable<thread_info */* t */,
> + gdb::optional<ULONGEST> /* exit_code */,
> + bool /* silent */> thread_exit;
>
> /* An explicit stop request was issued to PTID. If PTID equals
> minus_one_ptid, the request applied to all threads. If
> diff --git a/gdb/procfs.c b/gdb/procfs.c
> index ffc26c8fb9e..7d0e6e9a4c9 100644
> --- a/gdb/procfs.c
> +++ b/gdb/procfs.c
> @@ -2115,9 +2115,6 @@ procfs_target::wait (ptid_t ptid, struct target_waitstatus *status,
> case PR_SYSENTRY:
> if (what == SYS_lwp_exit)
> {
> - if (print_thread_events)
> - gdb_printf (_("[%s exited]\n"),
> - target_pid_to_str (retval).c_str ());
> delete_thread (find_thread_ptid (this, retval));
> target_continue_no_signal (ptid);
> goto wait_again;
> @@ -2222,9 +2219,6 @@ procfs_target::wait (ptid_t ptid, struct target_waitstatus *status,
> }
> else if (what == SYS_lwp_exit)
> {
> - if (print_thread_events)
> - gdb_printf (_("[%s exited]\n"),
> - target_pid_to_str (retval).c_str ());
> delete_thread (find_thread_ptid (this, retval));
> status->set_spurious ();
> return retval;
> diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
> index 4d5e09db680..be5597c4a2e 100644
> --- a/gdb/python/py-inferior.c
> +++ b/gdb/python/py-inferior.c
> @@ -360,7 +360,9 @@ add_thread_object (struct thread_info *tp)
> }
>
> static void
> -delete_thread_object (struct thread_info *tp, int ignore)
> +delete_thread_object (thread_info *tp,
> + gdb::optional<ULONGEST> /* exit_code */,
> + bool /* silent */)
> {
> if (!gdb_python_initialized)
> return;
> diff --git a/gdb/thread.c b/gdb/thread.c
> index 2ca3a867d8c..7ab30562fd3 100644
> --- a/gdb/thread.c
> +++ b/gdb/thread.c
> @@ -192,7 +192,8 @@ clear_thread_inferior_resources (struct thread_info *tp)
> /* See gdbthread.h. */
>
> void
> -set_thread_exited (thread_info *tp, bool silent)
> +set_thread_exited (thread_info *tp, gdb::optional<ULONGEST> exit_code,
> + bool silent)
> {
> /* Dead threads don't need to step-over. Remove from chain. */
> if (thread_is_in_step_over_chain (tp))
> @@ -211,7 +212,22 @@ set_thread_exited (thread_info *tp, bool silent)
> if (proc_target != nullptr)
> proc_target->maybe_remove_resumed_with_pending_wait_status (tp);
>
> - gdb::observers::thread_exit.notify (tp, silent);
> + if (!silent && print_thread_events)
> + {
> + if (exit_code.has_value ())
> + {
> + gdb_printf (_("[%s exited with code %s]\n"),
> + target_pid_to_str (tp->ptid).c_str (),
> + pulongest (*exit_code));
> + }
> + else
> + {
> + gdb_printf (_("[%s exited]\n"),
> + target_pid_to_str (tp->ptid).c_str ());
> + }
> + }
> +
> + gdb::observers::thread_exit.notify (tp, exit_code, silent);
>
> /* Tag it as exited. */
> tp->state = THREAD_EXITED;
> @@ -468,20 +484,22 @@ global_thread_step_over_chain_remove (struct thread_info *tp)
> global_thread_step_over_list.erase (it);
> }
>
> -/* Delete the thread referenced by THR. If SILENT, don't notify
> - the observer of this exit.
> -
> - THR must not be NULL or a failed assertion will be raised. */
> +/* Helper for the different delete_thread variants. */
>
> static void
> -delete_thread_1 (thread_info *thr, bool silent)
> +delete_thread_1 (thread_info *thr, gdb::optional<ULONGEST> exit_code,
> + bool silent)
> {
> gdb_assert (thr != nullptr);
>
> - threads_debug_printf ("deleting thread %s, silent = %d",
> - thr->ptid.to_string ().c_str (), silent);
> + threads_debug_printf ("deleting thread %s, exit_code = %s, silent = %d",
> + thr->ptid.to_string ().c_str (),
> + (exit_code.has_value ()
> + ? pulongest (*exit_code)
> + : "<none>"),
> + silent);
>
> - set_thread_exited (thr, silent);
> + set_thread_exited (thr, exit_code, silent);
>
> if (!thr->deletable ())
> {
> @@ -497,16 +515,25 @@ delete_thread_1 (thread_info *thr, bool silent)
>
> /* See gdbthread.h. */
>
> +void
> +delete_thread_with_exit_code (thread_info *thread, ULONGEST exit_code,
> + bool silent)
> +{
> + delete_thread_1 (thread, exit_code, false /* not silent */);
> +}
> +
> +/* See gdbthread.h. */
> +
> void
> delete_thread (thread_info *thread)
> {
> - delete_thread_1 (thread, false /* not silent */);
> + delete_thread_1 (thread, {}, false /* not silent */);
> }
>
> void
> delete_thread_silent (thread_info *thread)
> {
> - delete_thread_1 (thread, true /* silent */);
> + delete_thread_1 (thread, {}, true /* not silent */);
> }
>
> struct thread_info *
> diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
> index ee4e78bdabf..2764fc694b3 100644
> --- a/gdb/windows-nat.c
> +++ b/gdb/windows-nat.c
> @@ -611,21 +611,13 @@ windows_nat_target::delete_thread (ptid_t ptid, DWORD exit_code,
>
> id = ptid.lwp ();
>
> - /* Emit a notification about the thread being deleted.
> -
> - Note that no notification was printed when the main thread
> + /* Note that no notification was printed when the main thread
> was created, and thus, unless in verbose mode, we should be
> symmetrical, and avoid that notification for the main thread
> here as well. */
> -
> - if (info_verbose)
> - gdb_printf ("[Deleting %s]\n", target_pid_to_str (ptid).c_str ());
> - else if (print_thread_events && !main_thread_p)
> - gdb_printf (_("[%s exited with code %u]\n"),
> - target_pid_to_str (ptid).c_str (),
> - (unsigned) exit_code);
> -
> - ::delete_thread (find_thread_ptid (this, ptid));
> + bool silent = (main_thread_p && !info_verbose);
> + thread_info *todel = find_thread_ptid (this, ptid);
> + delete_thread_with_exit_code (todel, exit_code, silent);
>
> auto iter = std::find_if (windows_process.thread_list.begin (),
> windows_process.thread_list.end (),
> --
> 2.36.0