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* [binutils-gdb] gdbserver: Queue no-resumed event after thread exit
@ 2023-11-13 14:26 Pedro Alves
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From: Pedro Alves @ 2023-11-13 14:26 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ef980d654ba22aad6b5b301179dd105f522b56a1
commit ef980d654ba22aad6b5b301179dd105f522b56a1
Author: Pedro Alves <pedro@palves.net>
Date: Fri Apr 22 21:03:07 2022 +0100
gdbserver: Queue no-resumed event after thread exit
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
Diff:
---
gdbserver/linux-low.cc | 47 ++++++++++++++++++++++++++++-------------------
gdbserver/linux-low.h | 2 ++
gdbserver/server.cc | 12 +++++++++++-
gdbserver/target.cc | 6 ++++++
gdbserver/target.h | 6 ++++++
5 files changed, 53 insertions(+), 20 deletions(-)
diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index b4a1191b5b4..44d0fe38030 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -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
diff --git a/gdbserver/linux-low.h b/gdbserver/linux-low.h
index 3597e33289c..d46ea5aa3ec 100644
--- a/gdbserver/linux-low.h
+++ b/gdbserver/linux-low.h
@@ -259,6 +259,8 @@ public:
bool thread_stopped (thread_info *thread) override;
+ bool any_resumed () override;
+
void pause_all (bool freeze) override;
void unpause_all (bool unfreeze) override;
diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index 4a312da40bc..a8e23561dcb 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -4731,7 +4731,17 @@ handle_target_event (int err, gdb_client_data client_data)
}
}
else
- push_stop_notification (cs.last_ptid, cs.last_status);
+ {
+ push_stop_notification (cs.last_ptid, cs.last_status);
+
+ if (cs.last_status.kind () == TARGET_WAITKIND_THREAD_EXITED
+ && !target_any_resumed ())
+ {
+ target_waitstatus ws;
+ ws.set_no_resumed ();
+ push_stop_notification (null_ptid, ws);
+ }
+ }
}
/* Be sure to not change the selected thread behind GDB's back.
diff --git a/gdbserver/target.cc b/gdbserver/target.cc
index dbb4e2d9024..81edff41268 100644
--- a/gdbserver/target.cc
+++ b/gdbserver/target.cc
@@ -614,6 +614,12 @@ process_stratum_target::thread_stopped (thread_info *thread)
gdb_assert_not_reached ("target op thread_stopped not supported");
}
+bool
+process_stratum_target::any_resumed ()
+{
+ return true;
+}
+
bool
process_stratum_target::supports_get_tib_address ()
{
diff --git a/gdbserver/target.h b/gdbserver/target.h
index 0f1fd5906fb..28d134e7915 100644
--- a/gdbserver/target.h
+++ b/gdbserver/target.h
@@ -319,6 +319,9 @@ public:
/* Return true if THREAD is known to be stopped now. */
virtual bool thread_stopped (thread_info *thread);
+ /* Return true if any thread is known to be resumed. */
+ virtual bool any_resumed ();
+
/* Return true if the get_tib_address op is supported. */
virtual bool supports_get_tib_address ();
@@ -683,6 +686,9 @@ target_read_btrace_conf (struct btrace_target_info *tinfo,
#define target_supports_software_single_step() \
the_target->supports_software_single_step ()
+#define target_any_resumed() \
+ the_target->any_resumed ()
+
ptid_t mywait (ptid_t ptid, struct target_waitstatus *ourstatus,
target_wait_flags options, int connected_wait);
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