[PATCHv2 4/8] gdb, infrun: refactor part of `proceed` into separate function

Andrew Burgess via Gdb-patches
2023-07-04T15:26:43Z

From: Mihails Strasuns <mihails.strasuns@intel.com>

Split the thread resuming code from proceed into new function
proceed_resume_thread_checked.

Co-Authored-By: Christina Schimpe <christina.schimpe@intel.com>
---
gdb/infrun.c | 155 ++++++++++++++++++++++++++++-----------------------
1 file changed, 86 insertions(+), 69 deletions(-)

diff --git a/gdb/infrun.c b/gdb/infrun.c
index 5b0257076f0..010fcd7952f 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -3268,6 +3268,89 @@ check_multi_target_resumption (process_stratum_target *resume_target)
}
}

+/* Helper function for `proceed`. Check if thread TP is suitable for
+ resuming, and, if it is, switch to the thread and call
+ `keep_going_pass_signal`. If TP is not suitable for resuming then this
+ function will just return without switching threads. */
+
+static void
+proceed_resume_thread_checked (thread_info *tp)
+{
+ if (!tp->inf->has_execution ())
+ {
+ infrun_debug_printf ("[%s] target has no execution",
+ tp->ptid.to_string ().c_str ());
+ return;
+ }
+
+ if (tp->resumed ())
+ {
+ infrun_debug_printf ("[%s] resumed",
+ tp->ptid.to_string ().c_str ());
+ gdb_assert (tp->executing () || tp->has_pending_waitstatus ());
+ return;
+ }
+
+ if (thread_is_in_step_over_chain (tp))
+ {
+ infrun_debug_printf ("[%s] needs step-over",
+ tp->ptid.to_string ().c_str ());
+ return;
+ }
+
+ /* When handling a vfork GDB removes all breakpoints from the program
+ space in which the vfork is being handled, as such we must take care
+ not to resume any thread other than the vfork parent -- resuming the
+ vfork parent allows GDB to receive and handle the 'vfork done'
+ event. */
+ if (tp->inf->thread_waiting_for_vfork_done != nullptr)
+ {
+ if (target_is_non_stop_p ())
+ {
+ /* For non-stop targets, regardless of whether GDB is using
+ all-stop or non-stop mode, threads are controlled
+ individually.
+
+ When a thread is handling a vfork, breakpoints are removed
+ from the inferior (well, program space in fact), so it is
+ critical that we don't try to resume any thread other than the
+ vfork parent. */
+ if (tp != tp->inf->thread_waiting_for_vfork_done)
+ {
+ infrun_debug_printf ("[%s] thread %s of this inferior is "
+ "waiting for vfork-done",
+ tp->ptid.to_string ().c_str (),
+ tp->inf->thread_waiting_for_vfork_done
+ ->ptid.to_string ().c_str ());
+ return;
+ }
+ }
+ else
+ {
+ /* For all-stop targets, when we attempt to resume the inferior,
+ we will only resume the vfork parent thread, this is handled
+ in internal_resume_ptid.
+
+ Additionally, we will always be called with the vfork parent
+ thread as the current thread (TP) thanks to follow_fork, as
+ such the following assertion should hold.
+
+ Beyond this there is nothing more that needs to be done
+ here. */
+ gdb_assert (tp == tp->inf->thread_waiting_for_vfork_done);
+ }
+ }
+
+ infrun_debug_printf ("resuming %s",
+ tp->ptid.to_string ().c_str ());
+
+ execution_control_state ecs (tp);
+ switch_to_thread (tp);
+ keep_going_pass_signal (&ecs);
+ if (!ecs.wait_some_more)
+ error (_("Command aborted."));
+}
+
/* Basic routine for continuing the program in various fashions.

ADDR is the address to resume at, or -1 for resume where stopped.
@@ -3456,77 +3539,11 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
resume_ptid))
{
switch_to_thread_no_regs (tp);
-
- if (!tp->inf->has_execution ())
- {
- infrun_debug_printf ("[%s] target has no execution",
- tp->ptid.to_string ().c_str ());
- continue;
- }
-
- if (tp->resumed ())
- {
- infrun_debug_printf ("[%s] resumed",
- tp->ptid.to_string ().c_str ());
- gdb_assert (tp->executing () || tp->has_pending_waitstatus ());
- continue;
- }
-
- if (thread_is_in_step_over_chain (tp))
- {
- infrun_debug_printf ("[%s] needs step-over",
- tp->ptid.to_string ().c_str ());
- continue;
- }
-
- /* If a thread of that inferior is waiting for a vfork-done
- (for a detached vfork child to exec or exit), breakpoints are
- removed. We must not resume any thread of that inferior, other
- than the one waiting for the vfork-done. */
- if (tp->inf->thread_waiting_for_vfork_done != nullptr
- && tp != tp->inf->thread_waiting_for_vfork_done)
- {
- infrun_debug_printf ("[%s] another thread of this inferior is "
- "waiting for vfork-done",
- tp->ptid.to_string ().c_str ());
- continue;
- }
-
- infrun_debug_printf ("resuming %s",
- tp->ptid.to_string ().c_str ());
-
- execution_control_state ecs (tp);
- switch_to_thread (tp);
- keep_going_pass_signal (&ecs);
- if (!ecs.wait_some_more)
- error (_("Command aborted."));
- }
- }
- else if (!cur_thr->resumed ()
- && !thread_is_in_step_over_chain (cur_thr))
- {
- /* In non-stop mode, if a there exists a thread waiting for a vfork
- then only allow that thread to resume (breakpoints are removed
- from an inferior when handling a vfork).
-
- We check target_is_non_stop_p here rather than just checking the
- non-stop flag, though these are equivalent (all-stop on a
- non-stop target was handled in a previous block, so at this
- point, if target_is_non_stop_p then GDB must be running on
- non-stop mode). By using target_is_non_stop_p it will be easier
- to merge this block with the previous in a later commit. */
- if (!(target_is_non_stop_p ()
- && cur_thr->inf->thread_waiting_for_vfork_done != nullptr
- && cur_thr->inf->thread_waiting_for_vfork_done != cur_thr))
- {
- /* The thread wasn't started, and isn't queued, run it now. */
- execution_control_state ecs (cur_thr);
- switch_to_thread (cur_thr);
- keep_going_pass_signal (&ecs);
- if (!ecs.wait_some_more)
- error (_("Command aborted."));
+ proceed_resume_thread_checked (tp);
}
}
+ else
+ proceed_resume_thread_checked (cur_thr);

disable_commit_resumed.reset_and_commit ();
}
--
2.25.4