Re: [PATCH v2 4/5] obsd-nat: Various fixes for fork following.

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2021-07-27 1:41 p.m., John Baldwin wrote:
> - Don't use #ifdef's on ptrace ops.  obsd-nat.h didn't include
>   <sys/ptrace.h>, so the virtual methods weren't always overridden
>   causing the fork following to not work.  In addition, the thread and
>   fork code is intertwined in ::wait and and the lack of #ifdef's
>   there already assumed both were present.

In any case, PT_GET_PROCESS_STATE was added here, 16 years ago:

  https://github.com/openbsd/src/commit/f38bed7f869bd3503530c554b4860228ea4e8641

So it's reasonable to assume it's there (especially for a port with no
maintainer).

> 
> - Move duplicated code to enable PTRACE_FORK event reporting to a
>   single function and invoke it on new child processes reported via
>   PTRACE_FORK.
> 
> - Don't return early from PTRACE_FORK handling, but instead reset
>   wptid to the correct ptid if the child reports its event before the
>   parent.  This allows the ptid fixup code to add thread IDs if the
>   first event for a process is a PTRACE_FORK event.  This also
>   properly returns ptid's with thread IDs when reporting PTRACE_FORK
>   events.
> 
> - Handle detach_fork by skipping the PT_DETACH.
> ---
>  gdb/obsd-nat.c | 51 +++++++++++++++++++++++---------------------------
>  gdb/obsd-nat.h |  2 --
>  2 files changed, 23 insertions(+), 30 deletions(-)
> 
> diff --git a/gdb/obsd-nat.c b/gdb/obsd-nat.c
> index 8549c6ea66b..0edaa66cf1b 100644
> --- a/gdb/obsd-nat.c
> +++ b/gdb/obsd-nat.c
> @@ -33,8 +33,6 @@
>     that maps userland threads directly onto kernel threads in a 1:1
>     fashion.  */
>  
> -#ifdef PT_GET_THREAD_FIRST

10 years ago for this one.  Still long enough, and removing it makes the
code much simpler to understand.

> -
>  std::string
>  obsd_nat_target::pid_to_str (ptid_t ptid)
>  {
> @@ -72,6 +70,19 @@ obsd_nat_target::update_thread_list ()
>      }
>  }
>  
> +static void
> +obsd_enable_proc_events (pid_t pid)

Could you please write a small, oneliner comment for this one?

Simon