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

Andrew Burgess via Gdb-patches
2023-07-04T15:26:37Z

"Aktemur, Tankut Baris" <tankut.baris.aktemur@intel.com> writes:

> On Thursday, June 22, 2023 3:17 PM, Andrew Burgess wrote:
>> 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 | 148 +++++++++++++++++++++++++++------------------------
>> 1 file changed, 79 insertions(+), 69 deletions(-)
>>
>> diff --git a/gdb/infrun.c b/gdb/infrun.c
>> index 5b0257076f0..b10b7c59652 100644
>> --- a/gdb/infrun.c
>> +++ b/gdb/infrun.c
>> @@ -3268,6 +3268,82 @@ 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 in fact only resume the vfork parent thread, this is
>> + handled in internal_resume_ptid, as such, there is nothing
>> + more that needs doing here. */
>
> I wonder if here we should do
>
> gdb_assert (tp == tp->inf->thread_waiting_for_vfork_done);
>

That's a good idea. I've also updated the comment within this else
block as the current text doesn't really cover why this assert holds.

I've posted a V2 with this change.

Thanks,
Andrew

> -Baris
>
>> + }
>> + }
>> +
>> + 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 +3532,11 @@ 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
>
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