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gdbserver: Queue no-resumed event after thread exit

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Normally, if the last resumed thread on the target exits, the server
sends a no-resumed event to GDB.  If however, GDB enables the
GDB_THREAD_OPTION_EXIT option on a thread, and, that thread exits, the
server sends a thread exit event for that thread instead.

In all-stop RSP mode, since events can only be forwarded to GDB one at
a time, and the whole target stops whenever an event is reported, GDB
resumes the target again after getting a THREAD_EXITED event, and then
the server finally reports back a no-resumed event if/when
appropriate.

For non-stop RSP though, events are asynchronous, and if the server
sends a thread-exit event for the last resumed thread, the no-resumed
event is never sent.  This patch makes sure that in non-stop mode, the
server queues a no-resumed event after the thread-exit event if it was
the last resumed thread that exited.

Without this, we'd see failures in step-over-thread-exit testcases
added later in the series, like so:

   continue
   Continuing.
 - No unwaited-for children left.
 - (gdb) PASS: gdb.threads/step-over-thread-exit.exp: displaced-stepping=off: non-stop=on: target-non-stop=on: schedlock=off: ns_stop_all=1: continue stops when thread exits
 + FAIL: gdb.threads/step-over-thread-exit.exp: displaced-stepping=off: non-stop=on: target-non-stop=on: schedlock=off: ns_stop_all=1: continue stops when thread exits (timeout)

(and other similar ones)

Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I927d78b30f88236dbd5634b051a716f72420e7c7
This commit is contained in:
Pedro Alves
2022-04-22 21:03:07 +01:00
parent d828dbed9c
commit ef980d654b
5 changed files with 53 additions and 20 deletions
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47
gdbserver/linux-low.cc
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@@ -2972,7 +2972,6 @@ linux_process_target::wait_1 (ptid_t ptid, target_waitstatus *ourstatus,
int report_to_gdb;
int trace_event;
int in_step_range;
int any_resumed;
threads_debug_printf ("[%s]", target_pid_to_str (ptid).c_str ());
@@ -2986,23 +2985,7 @@ linux_process_target::wait_1 (ptid_t ptid, target_waitstatus *ourstatus,
in_step_range = 0;
ourstatus->set_ignore ();
auto status_pending_p_any = [&] (thread_info *thread)
{
return status_pending_p_callback (thread, minus_one_ptid);
};
auto not_stopped = [&] (thread_info *thread)
{
return not_stopped_callback (thread, minus_one_ptid);
};
/* Find a resumed LWP, if any. */
if (find_thread (status_pending_p_any) != NULL)
any_resumed = 1;
else if (find_thread (not_stopped) != NULL)
any_resumed = 1;
else
any_resumed = 0;
bool was_any_resumed = any_resumed ();
if (step_over_bkpt == null_ptid)
pid = wait_for_event (ptid, &w, options);
@@ -3013,7 +2996,7 @@ linux_process_target::wait_1 (ptid_t ptid, target_waitstatus *ourstatus,
pid = wait_for_event (step_over_bkpt, &w, options & ~WNOHANG);
}
if (pid == 0 || (pid == -1 && !any_resumed))
if (pid == 0 || (pid == -1 && !was_any_resumed))
{
gdb_assert (target_options & TARGET_WNOHANG);
@@ -6177,6 +6160,32 @@ linux_process_target::thread_stopped (thread_info *thread)
return get_thread_lwp (thread)->stopped;
}
bool
linux_process_target::any_resumed ()
{
bool any_resumed;
auto status_pending_p_any = [&] (thread_info *thread)
{
return status_pending_p_callback (thread, minus_one_ptid);
};
auto not_stopped = [&] (thread_info *thread)
{
return not_stopped_callback (thread, minus_one_ptid);
};
/* Find a resumed LWP, if any. */
if (find_thread (status_pending_p_any) != NULL)
any_resumed = 1;
else if (find_thread (not_stopped) != NULL)
any_resumed = 1;
else
any_resumed = 0;
return any_resumed;
}
/* This exposes stop-all-threads functionality to other modules. */
void