cippd_protocol.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef	lint
static char *sccsid = "@(#)cippd_protocol.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
 *		Computer Interconnect Port-to-Port Driver
 *
 *   Abstract:	This module contains Computer Interconnect Port-to-Port
 *		Driver( CI PPD ) finite state machine action functions and
 *		control routines.
 *
 *   Creator:	Todd M. Katz	Creation Date:	October 20, 1985
 *
 *   Function/Routines:
 *
 *   Control Routines
 *	cippd_dispatch		CI PPD Action Dispatcher
 *   Action Functions
 *	cippd_ack_rec		Discard Received ACK CI PPD Datagram
 *	cippd_build_sb		Build Formative System Block
 *	cippd_comp_trys		Compute Number of Transmission Attempts
 *	cippd_disb_path		Disable CI PPD Path
 *	cippd_enab_path		Enable CI PPD Path
 *	cippd_enter_db		Enter Path Block into Databases
 *	cippd_error_dg		Process Received ERROR CI PPD Datagram
 *	cippd_ignore_dg		Ignore CI PPD Datagram
 *	cippd_init_pb		Initialize a Path Block
 *	cippd_inv_cache		Invalidate Local Port Translation Cache
 *	cippd_panic		Unexpected State-Event Combination
 *	cippd_path_schd		Schedule Asynchronous CI PPD Path Clean Up
 *	cippd_pcreason		Map Path Crash Reason
 *	cippd_ppderror		Process CI PPD Protocol Errors
 *	cippd_req_id		Request Remote Port Identification
 *	cippd_rrestart		Process Remote CI PPD Path Restart Requests
 *	cippd_snd_ack		Send ACK CI PPD Datagram
 *	cippd_snd_stack		Send STACK CI PPD Datagram
 *	cippd_snd_start		Send START CI PPD Datagram
 *	cippd_snd_stop		Send STOP CI PPD Datagram
 *	cippd_start_tmr		Start CI PPD Traffic Interval Timer
 *	cippd_stop_dg		Process Received STOP CI PPD Datagram
 *	cippd_stop_tmr		Stop CI PPD Traffic Interval Timer
 *	cippd_test_trys		Test/Decrement Number of Transmission Attempts
 *	cippd_update_sb		Update Formative System Block
 *	cippd_upd_ptype		Update Hardware Port Type of Remote Port
 *
 *   Modification History:
 *
 *   14-Sep-1989	Pete Keilty
 *	1. Added bcmp instead of cast u_long for strings because of 
 *	   mips cpu's data alignment.
 *
 *   07-Sep-1989	Pete Keilty
 *	1. Added break in the scadb scan for loop of cippd_enter_db routine
 *	   on failure. This prevents Smp_unlock panic's lock not held.
 *	   On failure status is set to FAILURE so no need to continue 
 *	   scanning scadb.
 *
 *   06-Apr-1989	Pete Keilty
 *	1. Added include fiel smp_lock.h adn extern lock_t lk_scadb
 *
 *   17-Jan-1989	Todd M. Katz		TMK0005
 *	1. The macro Scaaddr_lol() has been renamed to Scaaddr_low().  It now
 *	   accesses only the low order word( instead of low order longword ) of
 *	   a SCA system address.
 *	2. Include header file ../vaxmsi/msisysap.h.
 *
 *   17-Aug-1988        Todd M. Katz		TMK0004
 *	 1. The following informational events( ES_I ) have been redefined as
 *	    warning events( ES_W ): TALKUP, BADSWTYPE.
 *	 2. The following informational events( ES_I ) have been redefined as
 *	    remote error events( ES_RE ): DBCONFLICT, RERROR.
 *	 3. The following informational events( ES_I ) have been redefined as
 *	    error events( ES_E ): TALKDOWN, ALLOCFAIL, NORETRIES.
 *	 4. Modifications to cippd_enter_db():
 *		1) Allow DSSI tape storage controllers( software type == TFXX )
 *		   to pass remote system software verification.
 *		2) Event log all new path establishments.
 *	 5. Routine cippd_error() has been changed to function cippd_ppderror()
 *	    and is invoked only when a CI PPD protocol violation occurs on a
 *	    formative path.  It processes all violations by explicitly logging
 *	    them with an error event code of SE_PPDPROTOCOL and returning a
 *	    failure status to force clean up of the formative path.
 *	 6. Add a new routine cippd_rrestart().  This routine is invoked only
 *	    when a START CI PPD datagram is received on a fully established
 *	    path.  Such datagrams indicate remote CI PPD termination and clean
 *	    up of the path and an attempt by the remote CI PPD to re-establish
 *	    it.
 *	 7. No need exists to cache the remote port station address in the PCCB
 *	    before invoking cippd_log_path().  Modify the following routines
 *	    and functions appropriately: cippd_build_sb(), cippd_enab_path(),
 *	    and cippd_test_trys().
 *	 8. Modify cippd_stop_dg() to crash only fully established paths.  The
 *	    reception of a STOP CI PPD datagram over a formative path is logged
 *	    before path establishment is aborted by returning a failure status.
 *	 9. Modifications to cippd_pcreason() are as follows:
 *		1) It is now invocable only on established paths.
 *		2) The amount of error checking performed by it during mapping
 *		   has been greatly increased.  A panic occurs when an invalid
 *		   path crash code is encountered.
 *		3) All invocations of appropriate PD specific mapping routines
 *		   have been eliminated.  Port driver specific path crash
 *		   reason codes no longer exist.  All reason code mapping takes
 *		   place entirely within this routine.
 *      	4) It now handles both severe and "routine" path crash reasons
 *		   as required by the newly redefined sca error code formats.
 *	10. Modify cippd_comp_trys() to obtain port polling contact frequency
 *	    from a CI PPD specific PCCB field instead of from a CI PPD
 *	    configuration variable.
 *	11. Refer to error logging as event logging.
 *
 *   03-Jun-1988	Todd M. Katz		TMK0003
 *      1. Modify cippd_build_sb() and cippd_enab_path() to event log instances
 *         of insufficient memory for new path establishment.
 *	2. Add logging of path establishment abortion due to exhausted retries.
 *	   This involves moving the check for exhausted retransmission attempts
 *	   from cippd_req_id(), cippd_snd_start(), and cippd_snd_stack() to a
 *	   new function, cippd_test_trys().  This new function determines
 *	   whether any retransmission attempts remain and aborts path
 *	   establishment when there are none.  This event is also logged
 *	   provided it is the first such failure to establish the path.
 *	   Logging of subsequent failures is bypassed until the CI PPD is
 *	   successful at establishing the path( cippd_enter_db() has been
 *	   appropriately modified ).
 *	3. Eliminate return of status by cippd_req_id(), cippd_snd_start(), and
 *	   cippd_snd_stack().  Formerly, these "routines" returned failure
 *	   status when unsuccessful at allocating a port specific buffer during
 *	   a retry attempt.  Such failures aborted path establishment.  Now
 *	   these routines just return on encountering an allocation failure.
 *	   The failure is not logged and path establishment is not aborted.
 *	   This change allows multiple attempts to be made to complete the
 *	   current step in the CI PPD path establishment sequence regardless of
 *	   intermediate failures.  Only when retries are exhausted is path
 *	   establishment aborted and the failure logged( by cippd_test_trys()).
 *	4. The following macros have been renamed:
 *		1) Test_mapbit() -> Test_lpinfomap()
 *		2) Set_mapbit() -> Set_lpinfomap()
 *		3) Clear_mapbit() -> Clear_lpinfomap()
 *	5. Eliminate the function cippd_chk_ver() and move its CI PPD protocol
 *	   checking function into cippd_enter_db().  Check for version
 *	   mismatches immediately after confirming that no database conflict
 *	   exists.  Also, modify cippd_enter_db() to log path establishments to
 *	   remote systems with unsupported system software types.  These
 *	   changes required extensive modifications to cippd_enter_db().
 *	6. CI PPD event logging is now split between the routines
 *	   cippd_log_path() and cippd_log_sys() to differentiate between
 *	   logging of path specific and system level events respectively.
 *	   Modify cippd_build_sb(), cippd_enab_path(), cippd_enter_db(), and
 *	   cippd_test_trys() to invoke cippd_log_path(); and, cippd_errorlog()
 *	   to invoke cippd_log_sys().
 *	7. Log the remote system's local port station address on database
 *	   conflicts( IE_DBCONFLICT ).
 *
 *   02-Jun-1988	Ricky S. Palmer
 *      Removed inclusion of header file ../vaxmsi/msisysap.h
 *
 *   09-Apr-1988	Todd M. Katz		TMK0002
 *	1. Add comments to cippd_dispatch() concerning disposal of optional
 *	   port specific message buffers.  Such buffers are always disposed of
 *	   external to the CI PPD finite state machine and never within it.
 *	2. Add use of Pb_fork() macro in place of straight-line code.
 *
 *   08-Jan-1988	Todd M. Katz		TMK0001
 *	Formated module, revised comments, increased robustness, made
 *	CI PPD and GVP completely independent from underlying port drivers,
 *	restructured code paths, and added SMP support.
 */

/*
 * 		Communication Interconnect Port-to-Port Driver
 * 
 * The CI PPD provides device independent paths for use as communication
 * conduits between equivalent SCSs on different systems.  The CI PPD is
 * responsible for the establishment and termination of these paths.  It is not
 * responsible for their maintenance.  That is the province of the port drivers
 * which monitor the physical status of their paths and notify the CI PPD when
 * a path has failed.  The CI PPD is also never involved with either SCS or
 * application communications.  Such communications are always handled directly
 * by the port drivers.
 *
 * Path establishment requires the CI PPD to communicate with equivalent CI
 * PPDs on other systems.  Such communication between peers utilizes a CI PPD
 * specific communication protocol consisting of a sequence of exchanged
 * datagrams triggered by the discovery of a previously unknown remote CI PPD.
 * The purpose of these datagram exchanges is for both participants to meet the
 * following criteria necessary for path establishment:
 *
 * 	1. Discovery of the remote CI PPD.
 *  	2. Transmission of local system information.
 * 	3. Reception of remote system information.
 * 	4. Transmission of an acknowledgement of remote system information.
 * 	5. Reception of an acknowledgement of local system information.
 *
 * The order in which these criteria are met may vary; and therefore, the
 * actual sequence of exchanged datagrams may also vary.  This is because the
 * path establishment CI PPD protocol is datagram based and the delivery of
 * datagrams is never guaranteed.  This requires a certain robustness to be
 * built into the path establishment protocol so that multiple attempts are
 * made to meet a particular criteria before aborting path establishment.
 * However, while the exact order of datagram exchanges may vary there are two
 * basic exchanges.
 *
 * 	        CI PPD 1		   	       CI PPD 2
 * 	-----------------------		------------------------------------
 *
 * 			Path Establishment Sequence 1
 *
 * 	Discovers Remote CI PPD
 * 	Transmits START -------------->
 * 					Discovers Remote CI PPD
 * 				<------	Transmits STACK
 * 	Transmits ACK ---------------->
 * 
 * 			Path Establishment Sequence 2
 * 
 * 	Discovers Remote CI PPD		Discovers Remote CI PPD
 * 	Transmits START ----------> <--	Transmits START
 * 	Transmits STACK ----------> <--	Transmits STACK
 * 	Transmits ACK ------------> <--	Transmits ACK
 * 
 * In the first sequence CI PPD 1 discovers CI PPD 2, transmits its system
 * information within a START CI PPD datagram, receives both remote system
 * information and an acknowledgement of its information within a STACK CI PPD
 * datagram, and transmits an acknowledgement of the remote information within
 * an ACK CI PPD datagram.  Meanwhile, CI PPD 2 receives remote system
 * information within a START, discovers CI PPD 1, transmits both its
 * information and an acknowledgement of the remote information within a STACK,
 * and receives acknowledgement of its information within an ACK.
 * 
 * In the second sequence both CI PPDs mirror their counterpart in what perhaps
 * is an overly redundant exchange of datagrams.  Both simultaneously discover
 * each other, transmit their system information within a START, receive their
 * counterpart's information also within a START, transmit an acknowledgement
 * of their counterpart's information within a STACK, receive an
 * acknowledgement of their information also within a STACK, and then transmit
 * a superfluous ACK for good measure.  All other path establishment sequences
 * are hybrids of these two basic sequences.
 * 
 * Discovery of the remote CI PPD is achieved by requesting the identification
 * of its remote port.  Such requests are accomplished in a port driver
 * specific fashion which may involve the underlying port's datagram
 * capabilities but never its guaranteed delivery mechanisms( if such exist ).
 * Two situations requiring remote port identification requests exist:
 *
 *	1. CI PPDs routinely poll all possible remote ports for their
 *	   identities.
 *	2. CI PPDs also request the identification of a specific remote port.
 *
 * The first situation represents how CI PPDs discover previously unknown
 * remote ports and the possible existence of their CI PPDs.  It is how CI PPD
 * 1 discovers CI PPD 2 in the first path establishment sequence.  The second
 * situation represents how a CI PPD discovers a remote port after receiving
 * its system information.  It is how CI PPD 2 discovers CI PPD 1 also in this
 * same sequence.  Polling( Situation 1 ) also provides one means by which
 * port drivers may monitor the physical state of their established paths.  
 * 
 * As mentioned, a certain robustness must be built into the path establishment
 * sequence because it is datagram based and datagrams are subject to both loss