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freebsd-dev/sys/rpc/svc_dg.c
John Baldwin 74fb0ba732 Rework socket upcalls to close some races with setup/teardown of upcalls. 
- Each socket upcall is now invoked with the appropriate socket buffer
  locked.  It is not permissible to call soisconnected() with this lock
  held; however, so socket upcalls now return an integer value.  The two
  possible values are SU_OK and SU_ISCONNECTED.  If an upcall returns
  SU_ISCONNECTED, then the soisconnected() will be invoked on the
  socket after the socket buffer lock is dropped.
- A new API is provided for setting and clearing socket upcalls.  The
  API consists of soupcall_set() and soupcall_clear().
- To simplify locking, each socket buffer now has a separate upcall.
- When a socket upcall returns SU_ISCONNECTED, the upcall is cleared from
  the receive socket buffer automatically.  Note that a SO_SND upcall
  should never return SU_ISCONNECTED.
- All this means that accept filters should now return SU_ISCONNECTED
  instead of calling soisconnected() directly.  They also no longer need
  to explicitly clear the upcall on the new socket.
- The HTTP accept filter still uses soupcall_set() to manage its internal
  state machine, but other accept filters no longer have any explicit
  knowlege of socket upcall internals aside from their return value.
- The various RPC client upcalls currently drop the socket buffer lock
  while invoking soreceive() as a temporary band-aid.  The plan for
  the future is to add a new flag to allow soreceive() to be called with
  the socket buffer locked.
- The AIO callback for socket I/O is now also invoked with the socket
  buffer locked.  Previously sowakeup() would drop the socket buffer
  lock only to call aio_swake() which immediately re-acquired the socket
  buffer lock for the duration of the function call.

Discussed with:	rwatson, rmacklem
2009-06-01 21:17:03 +00:00

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/* $NetBSD: svc_dg.c,v 1.4 2000/07/06 03:10:35 christos Exp $ */
/*
* Sun RPC is a product of Sun Microsystems, Inc. and is provided for
* unrestricted use provided that this legend is included on all tape
* media and as a part of the software program in whole or part. Users
* may copy or modify Sun RPC without charge, but are not authorized
* to license or distribute it to anyone else except as part of a product or
* program developed by the user.
*
* SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
* WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
* PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
*
* Sun RPC is provided with no support and without any obligation on the
* part of Sun Microsystems, Inc. to assist in its use, correction,
* modification or enhancement.
*
* SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
* INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
* OR ANY PART THEREOF.
*
* In no event will Sun Microsystems, Inc. be liable for any lost revenue
* or profits or other special, indirect and consequential damages, even if
* Sun has been advised of the possibility of such damages.
*
* Sun Microsystems, Inc.
* 2550 Garcia Avenue
* Mountain View, California 94043
*/
/*
* Copyright (c) 1986-1991 by Sun Microsystems Inc.
*/
#if defined(LIBC_SCCS) && !defined(lint)
#ident "@(#)svc_dg.c 1.17 94/04/24 SMI"
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* svc_dg.c, Server side for connectionless RPC.
*/
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/protosw.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sx.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <rpc/rpc.h>
#include <rpc/rpc_com.h>
static enum xprt_stat svc_dg_stat(SVCXPRT *);
static bool_t svc_dg_recv(SVCXPRT *, struct rpc_msg *,
struct sockaddr **, struct mbuf **);
static bool_t svc_dg_reply(SVCXPRT *, struct rpc_msg *,
struct sockaddr *, struct mbuf *);
static void svc_dg_destroy(SVCXPRT *);
static bool_t svc_dg_control(SVCXPRT *, const u_int, void *);
static int svc_dg_soupcall(struct socket *so, void *arg, int waitflag);
static struct xp_ops svc_dg_ops = {
.xp_recv = svc_dg_recv,
.xp_stat = svc_dg_stat,
.xp_reply = svc_dg_reply,
.xp_destroy = svc_dg_destroy,
.xp_control = svc_dg_control,
};
/*
* Usage:
* xprt = svc_dg_create(sock, sendsize, recvsize);
* Does other connectionless specific initializations.
* Once *xprt is initialized, it is registered.
* see (svc.h, xprt_register). If recvsize or sendsize are 0 suitable
* system defaults are chosen.
* The routines returns NULL if a problem occurred.
*/
static const char svc_dg_str[] = "svc_dg_create: %s";
static const char svc_dg_err1[] = "could not get transport information";
static const char svc_dg_err2[] = "transport does not support data transfer";
static const char __no_mem_str[] = "out of memory";
SVCXPRT *
svc_dg_create(SVCPOOL *pool, struct socket *so, size_t sendsize,
size_t recvsize)
{
SVCXPRT *xprt;
struct __rpc_sockinfo si;
struct sockaddr* sa;
int error;
if (!__rpc_socket2sockinfo(so, &si)) {
printf(svc_dg_str, svc_dg_err1);
return (NULL);
}
/*
* Find the receive and the send size
*/
sendsize = __rpc_get_t_size(si.si_af, si.si_proto, (int)sendsize);
recvsize = __rpc_get_t_size(si.si_af, si.si_proto, (int)recvsize);
if ((sendsize == 0) || (recvsize == 0)) {
printf(svc_dg_str, svc_dg_err2);
return (NULL);
}
xprt = svc_xprt_alloc();
sx_init(&xprt->xp_lock, "xprt->xp_lock");
xprt->xp_pool = pool;
xprt->xp_socket = so;
xprt->xp_p1 = NULL;
xprt->xp_p2 = NULL;
xprt->xp_ops = &svc_dg_ops;
error = so->so_proto->pr_usrreqs->pru_sockaddr(so, &sa);
if (error)
goto freedata;
memcpy(&xprt->xp_ltaddr, sa, sa->sa_len);
free(sa, M_SONAME);
xprt_register(xprt);
SOCKBUF_LOCK(&so->so_rcv);
soupcall_set(so, SO_RCV, svc_dg_soupcall, xprt);
SOCKBUF_UNLOCK(&so->so_rcv);
return (xprt);
freedata:
(void) printf(svc_dg_str, __no_mem_str);
if (xprt) {
svc_xprt_free(xprt);
}
return (NULL);
}
/*ARGSUSED*/
static enum xprt_stat
svc_dg_stat(SVCXPRT *xprt)
{
if (soreadable(xprt->xp_socket))
return (XPRT_MOREREQS);
return (XPRT_IDLE);
}
static bool_t
svc_dg_recv(SVCXPRT *xprt, struct rpc_msg *msg,
struct sockaddr **addrp, struct mbuf **mp)
{
struct uio uio;
struct sockaddr *raddr;
struct mbuf *mreq;
XDR xdrs;
int error, rcvflag;
/*
* Serialise access to the socket.
*/
sx_xlock(&xprt->xp_lock);
/*
* The socket upcall calls xprt_active() which will eventually
* cause the server to call us here. We attempt to read a
* packet from the socket and process it. If the read fails,
* we have drained all pending requests so we call
* xprt_inactive().
*/
uio.uio_resid = 1000000000;
uio.uio_td = curthread;
mreq = NULL;
rcvflag = MSG_DONTWAIT;
error = soreceive(xprt->xp_socket, &raddr, &uio, &mreq, NULL, &rcvflag);
if (error == EWOULDBLOCK) {
/*
* We must re-test for readability after taking the
* lock to protect us in the case where a new packet
* arrives on the socket after our call to soreceive
* fails with EWOULDBLOCK. The pool lock protects us
* from racing the upcall after our soreadable() call
* returns false.
*/
mtx_lock(&xprt->xp_pool->sp_lock);
if (!soreadable(xprt->xp_socket))
xprt_inactive_locked(xprt);
mtx_unlock(&xprt->xp_pool->sp_lock);
sx_xunlock(&xprt->xp_lock);
return (FALSE);
}
if (error) {
SOCKBUF_LOCK(&xprt->xp_socket->so_rcv);
soupcall_clear(xprt->xp_socket, SO_RCV);
SOCKBUF_UNLOCK(&xprt->xp_socket->so_rcv);
xprt_inactive(xprt);
sx_xunlock(&xprt->xp_lock);
return (FALSE);
}
sx_xunlock(&xprt->xp_lock);
xdrmbuf_create(&xdrs, mreq, XDR_DECODE);
if (! xdr_callmsg(&xdrs, msg)) {
XDR_DESTROY(&xdrs);
return (FALSE);
}
*addrp = raddr;
*mp = xdrmbuf_getall(&xdrs);
XDR_DESTROY(&xdrs);
return (TRUE);
}
static bool_t
svc_dg_reply(SVCXPRT *xprt, struct rpc_msg *msg,
struct sockaddr *addr, struct mbuf *m)
{
XDR xdrs;
struct mbuf *mrep;
bool_t stat = TRUE;
int error;
MGETHDR(mrep, M_WAIT, MT_DATA);
mrep->m_len = 0;
xdrmbuf_create(&xdrs, mrep, XDR_ENCODE);
if (msg->rm_reply.rp_stat == MSG_ACCEPTED &&
msg->rm_reply.rp_acpt.ar_stat == SUCCESS) {
if (!xdr_replymsg(&xdrs, msg))
stat = FALSE;
else
xdrmbuf_append(&xdrs, m);
} else {
stat = xdr_replymsg(&xdrs, msg);
}
if (stat) {
m_fixhdr(mrep);
error = sosend(xprt->xp_socket, addr, NULL, mrep, NULL,
0, curthread);
if (!error) {
stat = TRUE;
}
} else {
m_freem(mrep);
}
XDR_DESTROY(&xdrs);
xprt->xp_p2 = NULL;
return (stat);
}
static void
svc_dg_destroy(SVCXPRT *xprt)
{
SOCKBUF_LOCK(&xprt->xp_socket->so_rcv);
soupcall_clear(xprt->xp_socket, SO_RCV);
SOCKBUF_UNLOCK(&xprt->xp_socket->so_rcv);
sx_destroy(&xprt->xp_lock);
if (xprt->xp_socket)
(void)soclose(xprt->xp_socket);
if (xprt->xp_netid)
(void) mem_free(xprt->xp_netid, strlen(xprt->xp_netid) + 1);
svc_xprt_free(xprt);
}
static bool_t
/*ARGSUSED*/
svc_dg_control(xprt, rq, in)
SVCXPRT *xprt;
const u_int rq;
void *in;
{
return (FALSE);
}
static int
svc_dg_soupcall(struct socket *so, void *arg, int waitflag)
{
SVCXPRT *xprt = (SVCXPRT *) arg;
xprt_active(xprt);
return (SU_OK);
}
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