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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Tue, 17 Oct 2023 08:35:29 +0200
Message-ID: <CAMuHMdX3bXKNW=eoiQS6dw3LocYgr+wxi+D0xQKutmFxdmj3_Q@mail.gmail.com>
Subject: Re: [PATCH -next v3 1/2] sunrpc: Wrap read accesses to rpc_task.tk_pid
To:     Benjamin Coddington <bcodding@redhat.com>
Cc:     Geert Uytterhoeven <geert+renesas@glider.be>,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna@kernel.org>,
        Chuck Lever <chuck.lever@oracle.com>,
        Jeff Layton <jlayton@kernel.org>, Neil Brown <neilb@suse.de>,
        Olga Kornievskaia <kolga@netapp.com>,
        Dai Ngo <Dai.Ngo@oracle.com>, Tom Talpey <tom@talpey.com>,
        linux-nfs@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>
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Hi Ben.

On Mon, Oct 16, 2023 at 11:15 PM Benjamin Coddington
<bcodding@redhat.com> wrote:
> On 16 Oct 2023, at 9:09, Geert Uytterhoeven wrote:
> > The tk_pid member in the rpc_task structure exists conditionally on
> > debug or tracing being enabled.
> >
> > Introduce and use a wapper to read the value of this member, so users
> > outside tracing no longer have to care about these conditions.
> >
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202310121759.0CF34DcN-lkp@intel.com/
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>
> I never work on kernels that don't have tk_pid, but I can say its so useful
> that for 2 out of the 224 bytes that rpc_task uses (on aarch64), I'd be
> inclined to just include it all the time.  That way its around for folks to
> reference with realtime tools (like bpftrace, stap).

That would work, too.
In fact always including it should not increase the size of struct rpc_task,
as there's still unused spaced in the gap at the end.

> Does anyone know if there is a good reason not to include it for all
> configurations?
>
> Ben
>
> ..also:
> Reviewed-by: Benjamin Coddington <bcodding@redhat.com>

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds