Re: [PATCH v2] gdb/linux-tdep: use thread lwp instead of pid for info proc

[Kevin Buettner <kevinb@redhat.com>]

A couple of nits - 1) add a Bug tag/line to the commit message, and 2)
I got some whitespace nits when applying this patch.  See below.

On Sat, 12 Apr 2025 22:11:41 +0200
Disconnect3d <dominik.b.czarnota@gmail.com> wrote:

> This commit fixes bug #31207 where GDB shows an empty result
> of `info proc mappings` when we debug a non-main thread of a Linux
> process while the main thread has exitted. In such a case, the
> `/proc/<pid>/maps` file renders an empty file and `/proc/<lwp>/maps`
> should be used instead.
> 
> It is worth noting that the `/proc/<lwp>/` directories are not
> rendered by the Linux kernel when listing the procfs directory
> but they can be opened and they contain the usual procfs entries,
> just for the pid of the thread.

Please add:

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31207

> Signed-off-by: Disconnect3d <dominik.b.czarnota@gmail.com>
> ---
>  gdb/linux-tdep.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
> index 141c1199c8a..c141c9c6701 100644
> --- a/gdb/linux-tdep.c
> +++ b/gdb/linux-tdep.c
> @@ -842,7 +842,11 @@ linux_info_proc (struct gdbarch *gdbarch, const char *args,
>        if (current_inferior ()->fake_pid_p)
>  	error (_("Can't determine the current process's PID: you must name one."));
>  
> -      pid = current_inferior ()->pid;
> +      /* Use the thread's LWP ID instead of process ID when accessing procfs,
> +         since the LWP-specific entries provide more useful information.
> +         For example, /proc/<pid>/maps may be empty if the current thread has exited.

When applying this patch, "git am" complained that spaces were being used
instead of a tab for the above two lines.

> +      */
> +      pid = inferior_thread ()->ptid.lwp ();
>      }
>  
>    args = skip_spaces (args);

With those nits fixed, it's okay to push:

Approved-by: Kevin Buettner <kevinb@redhat.com>