[PATCH 26/28] Don't write to inferior_ptid in ravenscar-thread.c

Pedro Alves
2020-04-14T17:55:01Z

gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>

* ravenscar-thread.c (ravenscar_thread_target): Update.
(ravenscar_thread_target::update_inferior_ptid): Rename to ...
(ravenscar_thread_target::add_active_thread): ... this. Don't
set m_base_ptid here. Update to avoid referencing inferior_ptid.
(ravenscar_thread_target::wait): Don't write to inferior_ptid.
---
gdb/ravenscar-thread.c | 49 ++++++++++++++++++++++++-------------------------
1 file changed, 24 insertions(+), 25 deletions(-)

diff --git a/gdb/ravenscar-thread.c b/gdb/ravenscar-thread.c
index fd3beb03ec..93e02b1f40 100644
--- a/gdb/ravenscar-thread.c
+++ b/gdb/ravenscar-thread.c
@@ -77,8 +77,11 @@ static const target_info ravenscar_target_info = {
struct ravenscar_thread_target final : public target_ops
{
ravenscar_thread_target ()
+ : m_base_ptid (inferior_ptid)
{
- update_inferior_ptid ();
+ thread_info *thr = add_active_thread ();
+ if (thr != nullptr)
+ switch_to_thread (thr);
}

const target_info &info () const override
@@ -126,9 +129,9 @@ struct ravenscar_thread_target final : public target_ops
/* PTID of the last thread that received an event.
This can be useful to determine the associated task that received
the event, to make it the current task. */
- ptid_t m_base_ptid = null_ptid;
+ ptid_t m_base_ptid;

- void update_inferior_ptid ();
+ thread_info *add_active_thread ();
ptid_t active_task (int cpu);
bool task_is_currently_active (ptid_t ptid);
bool runtime_initialized ();
@@ -213,37 +216,36 @@ get_base_thread_from_ravenscar_task (ptid_t ptid)
return ptid_t (ptid.pid (), base_cpu, 0);
}

-/* Fetch the ravenscar running thread from target memory and
- update inferior_ptid accordingly. */
+/* Fetch the ravenscar running thread from target memory, make sure
+ there's a corresponding thread in the thread list, and return it.
+ If the runtime is not initialized, return NULL. */

-void
-ravenscar_thread_target::update_inferior_ptid ()
+thread_info *
+ravenscar_thread_target::add_active_thread ()
{
process_stratum_target *proc_target
= as_process_stratum_target (this->beneath ());

int base_cpu;

- m_base_ptid = inferior_ptid;
-
- gdb_assert (!is_ravenscar_task (inferior_ptid));
+ gdb_assert (!is_ravenscar_task (m_base_ptid));
base_cpu = ravenscar_get_thread_base_cpu (m_base_ptid);

- /* If the runtime has not been initialized yet, the inferior_ptid is
- the only ptid that there is. */
if (!runtime_initialized ())
- return;
+ return nullptr;

/* Make sure we set m_base_ptid before calling active_task
as the latter relies on it. */
- inferior_ptid = active_task (base_cpu);
- gdb_assert (inferior_ptid != null_ptid);
+ ptid_t active_ptid = active_task (base_cpu);
+ gdb_assert (active_ptid != null_ptid);

/* The running thread may not have been added to
system.tasking.debug's list yet; so ravenscar_update_thread_list
may not always add it to the thread list. Add it here. */
- if (!find_thread_ptid (proc_target, inferior_ptid))
- add_thread (proc_target, inferior_ptid);
+ thread_info *active_thr = find_thread_ptid (proc_target, active_ptid);
+ if (active_thr == nullptr)
+ active_thr = add_thread (proc_target, active_ptid);
+ return active_thr;
}

/* The Ravenscar Runtime exports a symbol which contains the ID of
@@ -343,12 +345,11 @@ ravenscar_thread_target::wait (ptid_t ptid,
= as_process_stratum_target (this->beneath ());
ptid_t event_ptid;

- inferior_ptid = m_base_ptid;
if (ptid != minus_one_ptid)
ptid = m_base_ptid;
event_ptid = beneath->wait (ptid, status, 0);
- /* Find any new threads that might have been created, and update
- inferior_ptid to the active thread.
+ /* Find any new threads that might have been created, and return the
+ active thread.

Only do it if the program is still alive, though. Otherwise,
this causes problems when debugging through the remote protocol,
@@ -357,13 +358,11 @@ ravenscar_thread_target::wait (ptid_t ptid,
if (status->kind != TARGET_WAITKIND_EXITED
&& status->kind != TARGET_WAITKIND_SIGNALLED)
{
- inferior_ptid = event_ptid;
+ m_base_ptid = event_ptid;
this->update_thread_list ();
- this->update_inferior_ptid ();
+ return this->add_active_thread ()->ptid;
}
- else
- inferior_ptid = m_base_ptid;
- return inferior_ptid;
+ return m_base_ptid;
}

/* Add the thread associated to the given TASK to the thread list
--
2.14.5