netdev - Re: [PATCH] sctp: mark sctp_do

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Message-ID: <CADvbK_d_3YQh0s_aOts3YiyHu_uxUxO4okCZDdi=+F4xbVnmKg@mail.gmail.com>
Date: Tue, 27 May 2025 10:23:37 -0400
From: Xin Long <lucien.xin@...il.com>
To: Benjamin Poirier <benjamin.poirier@...il.com>
Cc: Christoph Hellwig <hch@....de>, marcelo.leitner@...il.com, davem@...emloft.net, 
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, horms@...nel.org, 
	linux-sctp@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] sctp: mark sctp_do_peeloff static

On Mon, May 26, 2025 at 3:38 PM Benjamin Poirier
<benjamin.poirier@...il.com> wrote:
>
> On 2025-05-26 14:25 -0400, Xin Long wrote:
> > On Mon, May 26, 2025 at 1:47 AM Christoph Hellwig <hch@....de> wrote:
> > >
> > > sctp_do_peeloff is only used inside of net/sctp/socket.c,
> > > so mark it static.
> > >
> > > Signed-off-by: Christoph Hellwig <hch@....de>
> > > ---
> > >  include/net/sctp/sctp.h | 2 --
> > >  net/sctp/socket.c       | 4 ++--
> > >  2 files changed, 2 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
> > > index d8da764cf6de..e96d1bd087f6 100644
> > > --- a/include/net/sctp/sctp.h
> > > +++ b/include/net/sctp/sctp.h
> > > @@ -364,8 +364,6 @@ sctp_assoc_to_state(const struct sctp_association *asoc)
> > >  /* Look up the association by its id.  */
> > >  struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id);
> > >
> > > -int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp);
> > > -
> > >  /* A macro to walk a list of skbs.  */
> > >  #define sctp_skb_for_each(pos, head, tmp) \
> > >         skb_queue_walk_safe(head, pos, tmp)
> > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> > > index 53725ee7ba06..da048e386476 100644
> > > --- a/net/sctp/socket.c
> > > +++ b/net/sctp/socket.c
> > > @@ -5627,7 +5627,8 @@ static int sctp_getsockopt_autoclose(struct sock *sk, int len, char __user *optv
> > >  }
> > >
> > >  /* Helper routine to branch off an association to a new socket.  */
> > > -int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp)
> > > +static int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id,
> > > +               struct socket **sockp)
> > >  {
> > >         struct sctp_association *asoc = sctp_id2assoc(sk, id);
> > >         struct sctp_sock *sp = sctp_sk(sk);
> > > @@ -5675,7 +5676,6 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp)
> > >
> > >         return err;
> > >  }
> > > -EXPORT_SYMBOL(sctp_do_peeloff);
> > >
> > I believe sctp_do_peeloff() was exported specifically to allow usage
> > outside of the core SCTP code. See:
> >
> > commit 0343c5543b1d3ffa08e6716d82afb62648b80eba
> > Author: Benjamin Poirier <benjamin.poirier@...il.com>
> > Date:   Thu Mar 8 05:55:58 2012 +0000
> >
> >     sctp: Export sctp_do_peeloff
> >
>
> Thanks for digging that up. The purpose was of course for the commit
> that followed:
> 2f2d76cc3e93 dlm: Do not allocate a fd for peeloff (v3.4-rc1)
>
> Since that usage was removed in
> ee44b4bc054a dlm: use sctp 1-to-1 API (v4.3-rc1)
>
> I don't see a problem with marking sctp_do_peeloff() static again.
>
> > While there’s no known in-tree usage beyond SCTP itself, we can’t be
> > sure whether this function has been used by out-of-tree kernel modules.
>
> The mainline kernel does not need to cater to out-of-tree users.
Thank you for chiming in.

I didn't know it was exported for the in-tree kernel dlm, and this
patch should be applied to net-next.

Acked-by: Xin Long <lucien.xin@...il.com>