scs_msg.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef	lint
static char *sccsid = "@(#)scs_msg.c	4.1	(ULTRIX)	7/2/90";
#endif	lint

/************************************************************************
 *                                                                      *
 *                      Copyright (c) 1988 - 1989 by                    *
 *              Digital Equipment Corporation, Maynard, MA              *
 *                      All rights reserved.                            *
 *                                                                      *
 *   This software is furnished under a license and may be used and     *
 *   copied  only  in accordance with the terms of such license and     *
 *   with the  inclusion  of  the  above  copyright  notice.   This     *
 *   software  or  any  other copies thereof may not be provided or     *
 *   otherwise made available to any other person.  No title to and     *
 *   ownership of the software is hereby transferred.                   *
 *                                                                      *
 *   The information in this software is subject to change  without     *
 *   notice  and should not be construed as a commitment by Digital     *
 *   Equipment Corporation.                                             *
 *                                                                      *
 *   Digital assumes no responsibility for the use  or  reliability     *
 *   of its software on equipment which is not supplied by Digital.     *
 *                                                                      *
 ************************************************************************
 *
 *
 *   Facility:	Systems Communication Architecture
 *		Systems Communication Services
 *
 *   Abstract:	This module contains Systems Communication Services( SCS )
 *		sequenced message communication service functions.
 *
 *   Creator:	Todd M. Katz	Creation Date:	May 27, 1985
 *
 *   Function/Routines:
 *
 *   scs_alloc_msg		Allocate Application Message Buffer
 *   scs_dealloc_msg		Deallocate Application Message Buffer
 *   scs_mod_credits		Adjust Maximum Number of Send Credits
 *   scs_add_credit		Add back Reserved Send Credit
 *   scs_rsv_credit		Reserve Send Credit for Emergency Use
 *   scs_send_msg		Send Application Sequenced Message
 *
 *   Modification History:
 *
 *   06-Apr-1989	Pete Keilty
 *	Added include file smp_lock.h
 *
 *   06-Mar-1989	Todd M. Katz		TMK0003
 *	Include header file ../vaxmsi/msisysap.h.
 *
 *   02-Jun-1988     Ricky S. Palmer
 *	Removed inclusion of header file ../vaxmsi/msisysap.h
 *
 *   14-Mar-1988	Todd M. Katz		TMK0002
 *	Fixed typo in scs_send_msg by changing one instance of "==" to "="
 *	( which is what it should have been in the first place ).
 *
 *   08-Jan-1988	Todd M. Katz		TMK0001
 *	Formated module, revised comments, increased robustness, restructured
 *	code paths, and added SMP support.
 */

/* Libraries and Include Files.
 */
#include		"../h/types.h"
#include		"../h/param.h"
#include		"../h/ksched.h"
#include		"../h/time.h"
#include		"../h/errlog.h"
#include		"../h/smp_lock.h"
#ifdef mips
#include		"../h/systm.h"
#include		"../h/vmmac.h"
#endif mips
#include		"../io/scs/sca.h"
#include		"../io/scs/scaparam.h"
#include		"../io/ci/cippdsysap.h"
#include		"../io/ci/cisysap.h"
#include		"../io/msi/msisysap.h"
#include		"../io/bi/bvpsysap.h"
#include		"../io/gvp/gvpsysap.h"
#include		"../io/uba/uqsysap.h"
#include		"../io/sysap/sysap.h"
#include		"../io/ci/cippdscs.h"
#include		"../io/ci/ciscs.h"
#include		"../io/msi/msiscs.h"
#include		"../io/bi/bvpscs.h"
#include		"../io/gvp/gvpscs.h"
#include		"../io/uba/uqscs.h"
#include		"../io/scs/scs.h"

/* External Variables and Routines.
 */
extern	SCSIB		lscs;
extern	struct lock_t	lk_scadb;
extern	CBVTDB		*scs_cbvtdb;
extern	u_long		scs_cushion;
extern	void		scs_dispose_msg();

/*   Name:	scs_alloc_msg	- Allocate Application Message Buffer
 *
 *   Abstract:	This function allocates an application message buffer on a
 *		specific logical SCS connection.
 *
 *   Inputs:
 *
 *   IPL_SCS			- Interrupt processor level
 *   csb			- Communication Services Block pointer
 *	connid			-  Identification of logical SCS connection
 *   lscs			- Local system permanent information
 *   scs_cbvtdb			- CB vector table database pointer
 *
 *   Outputs:
 *
 *   IPL_SCS			- Interrupt processor level
 *   csb			- Communication Services Block pointer
 *	buf			-  Address of application data buffer
 *
 *   Return Values:
 *
 *   RET_SUCCESS		- Allocated application message buffer
 *   RET_ALLOCFAIL		- Failed to allocate storage
 *   RET_INVCONNID		- Invalid connection identification number
 *   RET_INVCSTATE		- Connection in invalid state
 *
 *   SMP:	The CB is locked to synchronize access and prevent deletion.
 *		It is indirectly locked through its CBVTE.
 */
u_long
scs_alloc_msg( csb )
    register CSB	*csb;
{
    register CB		*cb;
    register SCSH	*scsbp;
    register CBVTE	*cbvte;
    register u_long	status = RET_SUCCESS;

    /* Allocations of application message buffers proceed as follows:
     *
     * 1. Lock and retrieve the CB.
     * 2. Invoke a PD specific function to allocate a port specific message
     *	  buffer.
     * 3. Unlock the CB.
     * 4. Return an appropriate status.
     */
    Check_connid( csb->connid, cbvte, cb )
    if( cb->cinfo.cstate != CS_OPEN ) {
	status = RET_INVCSTATE;
    } else if(( scsbp = ( *cb->Alloc_msg )( cb->pccb ))) {
	csb->buf = Scs_to_appl( scsbp );
    } else {
	status = RET_ALLOCFAIL;
    }
    Unlock_cbvte( cbvte );
    return( status );
}

/*   Name:	scs_dealloc_msg	- Deallocate Application Message Buffer
 *
 *   Abstract:	This function deallocates an application message buffer on a
 *		specific logical SCS connection.  Under appropriate conditions
 *		the message buffer is converted into a receive message buffer
 *		for the logical SCS connection instead of deallocated.
 *
 *		Conversion of a message buffer into a receive message message
 *		buffer may trigger explicit extension of send credits across
 *		the logical SCS connection.
 *
 *   Inputs:
 *
 *   IPL_SCS			- Interrupt processor level
 *   csb			- Communication Services Block pointer
 *	buf			-  Address of application data buffer
 *	connid			-  Identification of logical SCS connection
 *   lscs			- Local system permanent information
 *   scs_cbvtdb			- CB vector table database pointer
 *
 *   Outputs:
 *
 *   IPL_SCS			- Interrupt processor level
 *   csb			- Communication Services Block pointer
 *	buf			-  NULL
 *
 *   Return Values:
 *
 *   RET_SUCCESS		- Deallocated application message buffer
 *   RET_INVCONNID		- Invalid connection identification number
 *   RET_INVCSTATE		- Connection in invalid state
 *
 *   SMP:	The CB is locked to synchronize access and prevent deletion.
 *		It is indirectly locked through its CBVTE.
 */
u_long
scs_dealloc_msg( csb )
    register CSB	*csb;
{
    register CB		*cb;
    register CBVTE	*cbvte;
    register u_long	status = RET_SUCCESS;

    /* Deallocations of application message buffers proceed as follows:
     *
     * 1. Lock and retrieve the CB.
     * 2. Dispose of the application message buffer according to the current
     *	  credit situation whenever the connection is open; otherwise invoke a
     *    PD specific routine to deallocate the port specific message buffer.
     * 3. Unlock the CB.
     * 4. Return an appropriate status.
     */
    Check_connid( csb->connid, cbvte, cb )
    if( cb->cinfo.cstate == CS_OPEN ) {
	( void )scs_dispose_msg( cb, Appl_to_scs( csb->buf ));
	csb->buf = NULL;
    } else if( cb->cinfo.cstate == CS_DISCONN_REC ||
	      cb->cinfo.cstate == CS_PATH_FAILURE ) {
	( void )( *cb->Dealloc_msg )( cb->pccb, Appl_to_scs( csb->buf ));
	csb->buf = NULL;
    } else {
	status = RET_INVCSTATE;
    }
    Unlock_cbvte( cbvte );
    return( status );
}

/*   Name:	scs_mod_credits	- Adjust Maximum Number of Send Credits
 *
 *   Abstract:	This function adjusts the maximum number of send credits that
 *		may be extended to a counterpart across a logical SCS
 *		connection.  This number may either be increased or decreased.
 *
 *		Partial increases or decreases in the maximum number of
 *		extendible send	credits may occur.
 *
 *		Explicit extension of send credits across the logical SCS
 *		connection may occur.
 *
 *   Inputs:
 *
 *   IPL_SCS			- Interrupt processor level
 *   csb			- Communication Services Block pointer
 *	connid			-  Identification of logical SCS connection
 *	ov3.ncredits		-  Number to adjust maximum send credits by
 *   lscs			- Local system permanent information
 *   lk_scadb			- SCA database lock structure
 *   scs_cbvtdb			- CB vector table database pointer
 *   scs_cushion		- SCS send credit cushion
 *
 *   Outputs:
 *
 *   IPL_SCS			- Interrupt processor level
 *   cb				- Connection Block pointer
 *	cinfo.cbstate		-  CB state
 *	cinfo.init_rec_credit	-  Remote SYSAP's maximum send credit
 *	cinfo.pend_rec_credit	-  Number of credits pending extension
 *   csb			- Communication Services Block pointer
 *	ov3.ncredits		-  Adjusted maximum number of send credits
 *
 *   Return Values:
 *
 *   RET_SUCCESS		- Modified maximum number of send credits
 *   RET_INVCONNID		- Invalid connection identification number
 *   RET_INVCSTATE		- Connection in invalid state
 *
 *   SMP:	The SCA database is locked in the event explicit extension of
 *		send credits to the SYSAP's remote counterpart is required.
 *
 *		The CB is locked to synchronize access and prevent deletion.
 *		It is indirectly locked through its CBVTE.
 *
 *		The PB is locked whenever it is found necessary to remove a CB
 *		from its SCS CB wait queue.
 */
u_long
scs_mod_credits( csb )
    register CSB	*csb;
{
    register CB		*cb;
    register SCSH	*scsbp;
    register CBVTE	*cbvte;
    register u_long	status = RET_SUCCESS;

    /* Adjustments in the maximum number of send credits proceed as follows:
     *
     * 1. Lock the SCA database.
     * 2. Lock and retrieve the CB.
     * 3. Adjust the number of send credits extendible across the connection
     *	  using PD specific functions and routines.  The maximum number of send
     *    credits may be increased by adding allocated port specific message
     *    buffers to the appropriate local port's free message pool.  The
     *    maximum number of send credits is decreased by deallocating receive
     *    message buffers withdrawn from the appropriate local port's free
     *	  message pool.  Only those buffer representing credits pending
     *	  extension may be withdrawn and deallocated.
     * 4. Perform connection bookkeeping.
     * 5. Retrieve the adjusted maximum number of extendible send credits.
     * 6. Unlock the CB and SCA database.
     * 7. Return an appropriate status.
     * 
     * Adjustments are immediately aborted on encountering any errors.
     *
     * Explicit SCS extension of send credits across the connection to the
     * SYSAP's remote counterpart is requested whenever:
     *
     * 1. SCS is not currently extending credits across the connection.
     * 2. There is at least one credit pending extension.
     * 3. The number of send credits held by the counterpart is less than its
     *    minimum credit requirement plus a local system-wide credit cushion.