binutils-gdb/gdb/target/waitstatus.h
Pedro Alves 65706a29ba Remote thread create/exit events
When testing with "maint set target-non-stop on", a few
threading-related tests expose an issue that requires new RSP packets.

Say there are 3 threads running, 1-3.  If GDB tries to stop thread 1,
2 and 3, and then waits for their stops, but meanwhile say, thread 2
exits, GDB hangs forever waiting for a stop for thread 2 that won't
ever happen.

This patch fixes the issue by adding support for thread exit events to
the protocol.  However, we don't want these always enabled, as they're
useless most of the time, and would slow down remote debugging.  So I
made it so that GDB can enable/disable them, and then made gdb do that
around the cases that need it, which currently is only
infrun.c:stop_all_threads.

In turn, if we have thread exit events, then the extra "thread x
exited" traffic slows down attach-many-short-lived-threads.exp enough
that gdb has trouble keeping up with new threads that are spawned
while gdb tries to stop existing ones.  To fix that I added support
for the counterpart thread created events too.  Enabling those when we
try to stop threads ensures that new threads never get a chance to
themselves start new threads, killing the race.

gdb/doc/ChangeLog:
2015-11-30  Pedro Alves  <palves@redhat.com>

	* gdb.texinfo (Remote Configuration): List "set/show remote
	thread-events" command in configuration table.
	(Stop Reply Packets): Document "T05 create" stop
	reason and 'w' stop reply.
	(General Query Packets): Document QThreadEvents packet.  Document
	QThreadEvents qSupported feature.

gdb/gdbserver/ChangeLog:
2015-11-30  Pedro Alves  <palves@redhat.com>

	* linux-low.c (handle_extended_wait): Assert that the LWP's
	waitstatus is TARGET_WAITKIND_IGNORE.  If GDB wants to hear about
	thread create events, leave the new child's status pending.
	(linux_low_filter_event): If GDB wants to hear about thread exit
	events, leave the LWP marked dead and don't delete it.
	(linux_wait_for_event_filtered): Don't check for thread exit.
	(filter_exit_event): New function.
	(linux_wait_1): Use it, when returning an exit event.
	(linux_resume_one_lwp_throw): Assert that the LWP's
	waitstatus is TARGET_WAITKIND_IGNORE.
	* remote-utils.c (prepare_resume_reply): Handle
	TARGET_WAITKIND_THREAD_CREATED and TARGET_WAITKIND_THREAD_EXITED.
	* server.c (report_thread_events): New global.
	(handle_general_set): Handle QThreadEvents.
	(handle_query) <qSupported>: Handle and report QThreadEvents+;
	(handle_target_event): Handle TARGET_WAITKIND_THREAD_CREATED and
	TARGET_WAITKIND_THREAD_EXITED.
	* server.h (report_thread_events): Declare.

gdb/ChangeLog:
2015-11-30  Pedro Alves  <palves@redhat.com>

	* NEWS (New commands): Mention "set/show remote thread-events"
	commands.
	(New remote packets): Mention thread created/exited stop reasons
	and QThreadEvents packet.
	* infrun.c (disable_thread_events): New function.
	(stop_all_threads): Disable/enable thread create/exit events.
	Handle TARGET_WAITKIND_THREAD_EXITED.
	(handle_inferior_event_1): Handle TARGET_WAITKIND_THREAD_CREATED
	and TARGET_WAITKIND_THREAD_EXITED.
	* remote.c (remove_child_of_pending_fork): Also remove threads of
	threads that have TARGET_WAITKIND_THREAD_EXITED events.
	(remote_parse_stop_reply): Handle "create" magic register.  Handle
	'w' stop reply.
	(initialize_remote): Install remote_thread_events as
	to_thread_events target hook.
	(remote_thread_events): New function.
	* target-delegates.c: Regenerate.
	* target.c (target_thread_events): New function.
	* target.h (struct target_ops) <to_thread_events>: New field.
	(target_thread_events): Declare.
	* target/waitstatus.c (target_waitstatus_to_string): Handle
	TARGET_WAITKIND_THREAD_CREATED and TARGET_WAITKIND_THREAD_EXITED.
	* target/waitstatus.h (enum target_waitkind)
	<TARGET_WAITKIND_THREAD_CREATED, TARGET_WAITKIND_THREAD_EXITED):
	New values.
2015-11-30 18:40:30 +00:00

152 lines
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C

/* Target waitstatus definitions and prototypes.
Copyright (C) 1990-2015 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef WAITSTATUS_H
#define WAITSTATUS_H
#include "gdb_signals.h"
/* Stuff for target_wait. */
/* Generally, what has the program done? */
enum target_waitkind
{
/* The program has exited. The exit status is in value.integer. */
TARGET_WAITKIND_EXITED,
/* The program has stopped with a signal. Which signal is in
value.sig. */
TARGET_WAITKIND_STOPPED,
/* The program has terminated with a signal. Which signal is in
value.sig. */
TARGET_WAITKIND_SIGNALLED,
/* The program is letting us know that it dynamically loaded
something (e.g. it called load(2) on AIX). */
TARGET_WAITKIND_LOADED,
/* The program has forked. A "related" process' PTID is in
value.related_pid. I.e., if the child forks, value.related_pid
is the parent's ID. */
TARGET_WAITKIND_FORKED,
/* The program has vforked. A "related" process's PTID is in
value.related_pid. */
TARGET_WAITKIND_VFORKED,
/* The program has exec'ed a new executable file. The new file's
pathname is pointed to by value.execd_pathname. */
TARGET_WAITKIND_EXECD,
/* The program had previously vforked, and now the child is done
with the shared memory region, because it exec'ed or exited.
Note that the event is reported to the vfork parent. This is
only used if GDB did not stay attached to the vfork child,
otherwise, a TARGET_WAITKIND_EXECD or
TARGET_WAITKIND_EXIT|SIGNALLED event associated with the child
has the same effect. */
TARGET_WAITKIND_VFORK_DONE,
/* The program has entered or returned from a system call. On
HP-UX, this is used in the hardware watchpoint implementation.
The syscall's unique integer ID number is in
value.syscall_id. */
TARGET_WAITKIND_SYSCALL_ENTRY,
TARGET_WAITKIND_SYSCALL_RETURN,
/* Nothing happened, but we stopped anyway. This perhaps should
be handled within target_wait, but I'm not sure target_wait
should be resuming the inferior. */
TARGET_WAITKIND_SPURIOUS,
/* An event has occured, but we should wait again.
Remote_async_wait() returns this when there is an event
on the inferior, but the rest of the world is not interested in
it. The inferior has not stopped, but has just sent some output
to the console, for instance. In this case, we want to go back
to the event loop and wait there for another event from the
inferior, rather than being stuck in the remote_async_wait()
function. This way the event loop is responsive to other events,
like for instance the user typing. */
TARGET_WAITKIND_IGNORE,
/* The target has run out of history information,
and cannot run backward any further. */
TARGET_WAITKIND_NO_HISTORY,
/* There are no resumed children left in the program. */
TARGET_WAITKIND_NO_RESUMED,
/* The thread was created. */
TARGET_WAITKIND_THREAD_CREATED,
/* The thread has exited. The exit status is in value.integer. */
TARGET_WAITKIND_THREAD_EXITED,
};
struct target_waitstatus
{
enum target_waitkind kind;
/* Additional information about the event. */
union
{
/* Exit status */
int integer;
/* Signal number */
enum gdb_signal sig;
/* Forked child pid */
ptid_t related_pid;
/* execd pathname */
char *execd_pathname;
/* Syscall number */
int syscall_number;
} value;
};
/* Extended reasons that can explain why a target/thread stopped for a
trap signal. */
enum target_stop_reason
{
/* Either not stopped, or stopped for a reason that doesn't require
special tracking. */
TARGET_STOPPED_BY_NO_REASON,
/* Stopped by a software breakpoint. */
TARGET_STOPPED_BY_SW_BREAKPOINT,
/* Stopped by a hardware breakpoint. */
TARGET_STOPPED_BY_HW_BREAKPOINT,
/* Stopped by a watchpoint. */
TARGET_STOPPED_BY_WATCHPOINT,
/* Stopped by a single step finishing. */
TARGET_STOPPED_BY_SINGLE_STEP
};
/* Prototypes */
/* Return a pretty printed form of target_waitstatus.
Space for the result is malloc'd, caller must free. */
extern char *target_waitstatus_to_string (const struct target_waitstatus *);
#endif /* WAITSTATUS_H */