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

Pedro Alves
2022-12-12T20:34:12Z

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:

(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