Re: [PATCH] sctp: mark sctp_do_peeloff static

On 2025-05-26 14:25 -0400, Xin Long wrote:

On Mon, May 26, 2025 at 1:47 AM Christoph Hellwig [off-list ref] wrote:

quoted

sctp_do_peeloff is only used inside of net/sctp/socket.c,
so mark it static.

Signed-off-by: Christoph Hellwig <hch@lst.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 [off-list ref]
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.