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Date:      Fri, 8 Jun 2018 19:35:25 +0000 (UTC)
From:      "Jonathan T. Looney" <jtl@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r334853 - in head: share/man/man9 sys/kern sys/sys
Message-ID:  <201806081935.w58JZPLM055582@repo.freebsd.org>
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Author: jtl
Date: Fri Jun  8 19:35:24 2018
New Revision: 334853
URL: https://svnweb.freebsd.org/changeset/base/334853

Log:
  Add a socket destructor callback.  This allows kernel providers to set
  callbacks to perform additional cleanup actions at the time a socket is
  closed.
  
  Michio Honda presented a use for this at BSDCan 2018.
  (See https://www.bsdcan.org/2018/schedule/events/965.en.html .)
  
  Submitted by:	Michio Honda <micchie at sfc.wide.ad.jp> (previous version)
  Reviewed by:	lstewart (previous version)
  Differential Revision:	https://reviews.freebsd.org/D15706

Modified:
  head/share/man/man9/socket.9
  head/sys/kern/uipc_socket.c
  head/sys/sys/socketvar.h

Modified: head/share/man/man9/socket.9
==============================================================================
--- head/share/man/man9/socket.9	Fri Jun  8 18:54:47 2018	(r334852)
+++ head/share/man/man9/socket.9	Fri Jun  8 19:35:24 2018	(r334853)
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 26, 2014
+.Dd June 8, 2018
 .Dt SOCKET 9
 .Os
 .Sh NAME
@@ -54,6 +54,11 @@
 .Fc
 .Ft int
 .Fn sodisconnect "struct socket *so"
+.Ft void
+.Fo sodtor_set
+.Fa "struct socket *so" 
+.Fa "void (*func)(struct socket *)"
+.Fc
 .Ft struct  sockaddr *
 .Fn sodupsockaddr "const struct sockaddr *sa" "int mflags"
 .Ft void
@@ -369,6 +374,13 @@ be cleared, with
 .Dv SO_RCV
 or
 .Dv SO_SND .
+.Ss Socket Destructor Callback
+A kernel system can use the
+.Fn sodtor_set
+function to set a destructor for a socket.
+The destructor is called when the socket is closed.
+The destructor is called after the protocol close routine has completed.
+The destructor can serve as a callback to initiate additional cleanup actions.
 .Ss Socket I/O
 The
 .Fn soreceive

Modified: head/sys/kern/uipc_socket.c
==============================================================================
--- head/sys/kern/uipc_socket.c	Fri Jun  8 18:54:47 2018	(r334852)
+++ head/sys/kern/uipc_socket.c	Fri Jun  8 19:35:24 2018	(r334853)
@@ -1101,6 +1101,8 @@ soclose(struct socket *so)
 drop:
 	if (so->so_proto->pr_usrreqs->pru_close != NULL)
 		(*so->so_proto->pr_usrreqs->pru_close)(so);
+	if (so->so_dtor != NULL)
+		so->so_dtor(so);
 
 	SOCK_LOCK(so);
 	if ((listening = (so->so_options & SO_ACCEPTCONN))) {
@@ -3810,6 +3812,17 @@ sodupsockaddr(const struct sockaddr *sa, int mflags)
 	if (sa2)
 		bcopy(sa, sa2, sa->sa_len);
 	return sa2;
+}
+
+/*
+ * Register per-socket destructor.
+ */
+void
+sodtor_set(struct socket *so, so_dtor_t *func)
+{
+
+	SOCK_LOCK_ASSERT(so);
+	so->so_dtor = func;
 }
 
 /*

Modified: head/sys/sys/socketvar.h
==============================================================================
--- head/sys/sys/socketvar.h	Fri Jun  8 18:54:47 2018	(r334852)
+++ head/sys/sys/socketvar.h	Fri Jun  8 19:35:24 2018	(r334853)
@@ -63,6 +63,7 @@ struct vnet;
  * private data and error information.
  */
 typedef	int so_upcall_t(struct socket *, void *, int);
+typedef	void so_dtor_t(struct socket *);
 
 struct socket;
 
@@ -99,6 +100,7 @@ struct socket {
 	/* NB: generation count must not be first. */
 	so_gen_t so_gencnt;		/* (h) generation count */
 	void	*so_emuldata;		/* (b) private data for emulators */
+	so_dtor_t *so_dtor;		/* (b) optional destructor */
 	struct	osd	osd;		/* Object Specific extensions */
 	/*
 	 * so_fibnum, so_user_cookie and friends can be used to attach
@@ -397,6 +399,7 @@ int	soconnect2(struct socket *so1, struct socket *so2)
 int	socreate(int dom, struct socket **aso, int type, int proto,
 	    struct ucred *cred, struct thread *td);
 int	sodisconnect(struct socket *so);
+void	sodtor_set(struct socket *, so_dtor_t *);
 struct	sockaddr *sodupsockaddr(const struct sockaddr *sa, int mflags);
 void	sofree(struct socket *so);
 void	sohasoutofband(struct socket *so);

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