Re: [PATCH v3 6/7] gdb: move clearing of tp->pending_follow to follow_fork_inferior

[Pedro Alves <pedro@palves.net>]

On 2021-12-01 14:44, Simon Marchi via Gdb-patches wrote:
> From: Simon Marchi <simon.marchi@efficios.com>
> 
> A following patch will change targets so that when they detach an
> inferior, they also detach any pending fork children this inferior may
> have.  While doing this, I hit a case where we couldn't differentiate
> two cases, where in one we should detach the fork detach but not in the
> other.
> 
> Suppose we continue past a fork with "follow-fork-mode == child" &&
> "detach-on-fork on".  follow_fork_inferior calls target_detach to detach
> the parent.  In that case the target should not detach the fork
> child, as we'll continue debugging the child.  As of now, the
> tp->pending_follow field of the thread who called fork still contains
> the details about the fork.
> 
> Then, suppose we run to a fork catchpoint and the user types "detach".
> In that case, the target should detach the fork child in addition to the
> parent.  In that case as well, the tp->pending_follow field contains
> the details about the fork.
> 
> To allow targets to differentiate the two cases, clear
> tp->pending_follow a bit earlier, when following a fork.  Targets will
> then see that tp->pending_follow contains TARGET_WAITKIND_SPURIOUS, and
> won't detach the fork child.
> 
> As of this patch, no behavior changes are expected.
> 

OK.