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

Pedro Alves
2023-03-10T17:21:48Z

On 2023-02-04 4:05 p.m., Andrew Burgess wrote:

> You mention gdb.threads/attach-many-short-lived-threads.exp as an
> example, but I don't think that test actually fails due to this issue,
> right?

Right.

> It might be worth mentioning gdb.threads/thread-specific-bp.exp, that is
> a test script that should actually start passing after this commit.
>

Meanwhile, this:

commit 89702edd933a5595557bcd9cc4a0dcc3262226d4
Author: Tom de Vries <tdevries@suse.de>
AuthorDate: Thu Mar 9 12:31:26 2023 +0100
Commit: Tom de Vries <tdevries@suse.de>
CommitDate: Thu Mar 9 12:31:26 2023 +0100

[gdb/testsuite] Fix gdb.threads/thread-specific-bp.exp on native-gdbserver

fixed that test in a different way, so this series no longer has an
effect there.

Your tests for PR gdb/30129 have since gone in too, so I'm referring to
those instead, and also removing their kfails, of course.

Below's the updated patch. I've also pushed the whole series to the

users/palves/step-over-thread-exit-v3.1

branch, for your convenience.

Let me know what you think.

From 9ec64120f3208d2ef4294e261e8641184d1bf2b9 Mon Sep 17 00:00:00 2001
From: Pedro Alves <pedro@palves.net>
Date: Tue, 21 Jun 2022 19:30:48 +0100
Subject: [PATCH] Centralize "[Thread ...exited]" notifications

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).

The fact that remote is missing thread exited messages is PR
remote/30129, and kfailed in gdb.threads/thread-bp-deleted.exp and
gdb.mi/mi-thread-bp-deleted.exp. This commit removes the now
unnecessary kfails (and kpasses) from those testcases, switching to
simpler gdb_assert instead.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30129
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/testsuite/gdb.mi/mi-thread-bp-deleted.exp | 18 ++-----
.../gdb.threads/thread-bp-deleted.exp | 12 +----
gdb/thread.c | 51 ++++++++++++++-----
gdb/windows-nat.c | 16 ++----
16 files changed, 95 insertions(+), 83 deletions(-)

diff --git a/gdb/annotate.c b/gdb/annotate.c
index 60fe6ccd5c2..a24841f7c0d 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 a42d26fd25a..25c98919d94 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -3243,7 +3243,9 @@ 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 27d2fe45092..612ebcc924f 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 79dedb23d4d..905ed8bddd5 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 80d53bb4e81..ee710964249 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -223,7 +223,7 @@ 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 d64e7cc015c..4c2d0505a91 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -697,6 +697,8 @@ 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 043c9a0489c..dcd5d07728d 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 e1244f3df43..dd1dc3126eb 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);
@@ -345,8 +347,10 @@ 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 37f2fa49b0b..133a3cf788f 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 efd0446e168..d6be15348d5 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 741e62a2402..a8a50c4ddc5 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 8b21f28afbe..5bb9d6a9fdc 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/testsuite/gdb.mi/mi-thread-bp-deleted.exp b/gdb/testsuite/gdb.mi/mi-thread-bp-deleted.exp
index 0ebca924801..6830991cc81 100644
--- a/gdb/testsuite/gdb.mi/mi-thread-bp-deleted.exp
+++ b/gdb/testsuite/gdb.mi/mi-thread-bp-deleted.exp
@@ -233,19 +233,11 @@ foreach_mi_ui_mode mode {
exp_continue
}

- # The output has arrived! Check how we did. There are other bugs
- # that come into play here which change what output we'll see.
- if { $saw_mi_thread_exited && $saw_mi_bp_deleted \
- && $saw_cli_thread_exited \
- && $saw_cli_bp_deleted } {
- kpass "gdb/30129" $gdb_test_name
- } elseif { $saw_mi_thread_exited && $saw_mi_bp_deleted \
- && !$saw_cli_thread_exited \
- && $saw_cli_bp_deleted } {
- kfail "gdb/30129" $gdb_test_name
- } else {
- fail "$gdb_test_name"
- }
+ # The output has arrived! Check how we did.
+ gdb_assert { $saw_mi_thread_exited && $saw_mi_bp_deleted \
+ && $saw_cli_thread_exited \
+ && $saw_cli_bp_deleted } \
+ $gdb_test_name
}
}

diff --git a/gdb/testsuite/gdb.threads/thread-bp-deleted.exp b/gdb/testsuite/gdb.threads/thread-bp-deleted.exp
index 019bdddee81..92178ff838b 100644
--- a/gdb/testsuite/gdb.threads/thread-bp-deleted.exp
+++ b/gdb/testsuite/gdb.threads/thread-bp-deleted.exp
@@ -155,17 +155,7 @@ if {$is_remote} {
exp_continue
}

- # When PR gdb/30129 is fixed then this can all be collapsed down
- # into a single gdb_assert call. This is split out like this
- # because the SAW_BP_DELETED part is working, and we want to
- # spot if that stops working.
- if { $saw_thread_exited && $saw_bp_deleted } {
- kpass "gdb/30129" $gdb_test_name
- } elseif {!$saw_thread_exited && $saw_bp_deleted} {
- kfail "gdb/30129" $gdb_test_name
- } else {
- fail $gdb_test_name
- }
+ gdb_assert { $saw_thread_exited && $saw_bp_deleted } $gdb_test_name
}
}
} else {
diff --git a/gdb/thread.c b/gdb/thread.c
index 0c5039530b0..d6b3f074e78 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -193,7 +193,8 @@ 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))
@@ -212,7 +213,22 @@ 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;
@@ -469,20 +485,22 @@ 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 ())
{
@@ -498,16 +516,25 @@ 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 26ad04b27be..03123e777eb 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -612,21 +612,13 @@ 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 (),

base-commit: 2562954ede66f32bff7d985e752b8052c2ae5775
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prerequisite-patch-id: 39c82dddeb7135a8a5dcfeeda3f5990d1564f845
prerequisite-patch-id: 4d3f5c603d36dc2df7b9363021044fdab0b60c90
prerequisite-patch-id: 25d7d10e191b1b7310e2c95a787a1b48286302b8
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2.36.0