11  * Fibre Channel exchange and sequence handling.
38  * fc_exch_mgr holds the exchange state for an N port
40  * fc_exch holds state for one exchange and links to its active sequence.
46  * struct fc_exch_pool - Per cpu exchange pool
47  * @next_index:	  Next possible free exchange index
54  * This structure manages per cpu exchanges in array of exchange pointers.
69  * struct fc_exch_mgr - The Exchange Manager (EM).
72  * @min_xid:	    Minimum exchange ID
73  * @max_xid:	    Maximum exchange ID
74  * @ep_pool:	    Reserved exchange pointers
77  * @lport:	    Local exchange port
81  * It manages the allocation of exchange IDs.
105  * @ema_list: Exchange Manager Anchor list
106  * @mp:	      Exchange Manager associated with this anchor
131  * The exchange manager is one by default in libfc but LLD may choose
132  * to have one per CPU. The sequence manager is one per exchange manager
138  * qualified by exchange ID, which one might think it would be.
140  * per session.	 For most targets we could treat this limit as per exchange.
142  * The exchange and its sequence are freed when the last sequence is received.
143  * It's possible for the remote port to leave an exchange open without
148  * Exchanges are reference counted and exchange gets freed when the reference
165  *	    with exchange and sequence tuple.
167  *	    When we receive the next sequence on the same exchange, we can
201  *  - exchange refcnt can be done atomicly without locks.
244  * fc_exch_hold() - Increment an exchange's reference count
255  * @ep:	   The exchange to that will use the header
305  * fc_exch_release() - Decrement an exchange's reference count
306  * @ep: Exchange to be released
308  * If the reference count reaches zero and the exchange is complete,
326  * @ep:		The exchange whose timer to be canceled
331 		FC_EXCH_DBG(ep, "Exchange timer canceled\n");  in fc_exch_timer_cancel()
337  * fc_exch_timer_set_locked() - Start a timer for an exchange w/ the
338  *				the exchange lock held
339  * @ep:		The exchange whose timer will start
342  * Used for upper level protocols to time out the exchange.
343  * The timer is cancelled when it fires or when the exchange completes.
351 	FC_EXCH_DBG(ep, "Exchange timer armed : %d msecs\n", timer_msec);  in fc_exch_timer_set_locked()
356 		FC_EXCH_DBG(ep, "Exchange already queued\n");  in fc_exch_timer_set_locked()
362  * fc_exch_timer_set() - Lock the exchange and set the timer
363  * @ep:		The exchange whose timer will start
374  * fc_exch_done_locked() - Complete an exchange with the exchange lock held
375  * @ep: The exchange that is complete
404  * fc_exch_ptr_get() - Return an exchange from an exchange pool
405  * @pool:  Exchange Pool to get an exchange from
406  * @index: Index of the exchange within the pool
408  * Use the index to get an exchange from within an exchange pool. exches
409  * will point to an array of exchange pointers. The index will select
410  * the exchange within the array.
420  * fc_exch_ptr_set() - Assign an exchange to a slot in an exchange pool
421  * @pool:  The pool to assign the exchange to
422  * @index: The index in the pool where the exchange will be assigned
423  * @ep:	   The exchange to assign to the pool
432  * fc_exch_delete() - Delete an exchange
433  * @ep: The exchange to be deleted
505 	 * Update the exchange and sequence flags,  in fc_seq_send_locked()
517  * fc_seq_send() - Send a frame using existing sequence/exchange pair
518  * @lport: The local port that the exchange will be sent on
520  * @fp:	   The frame to be sent on the exchange
538  * fc_seq_alloc() - Allocate a sequence for a given exchange
539  * @ep:	    The exchange to allocate a new sequence for
542  * We don't support multiple originated sequences on the same exchange.
543  * By implication, any previously originated sequence on this exchange
559  *				exchange as the supplied sequence
560  * @sp: The sequence/exchange to get a new sequence for
573  * fc_seq_start_next() - Lock the exchange and get a new sequence
574  *			 for a given sequence/exchange pair
575  * @sp: The sequence/exchange to get a new exchange for
590  * Set the response handler for the exchange associated with a sequence.
618  * fc_exch_abort_locked() - Abort an exchange
619  * @ep:	The exchange to be aborted
622  * Abort an exchange and sequence. Generally called because of a
623  * exchange timeout or an abort from the upper layer.
626  * timer_msec value is specified then exchange resp handler
684  * fc_seq_exch_abort() - Abort an exchange and sequence
706  * @ep:	   The exchange to be operated on
761  * fc_exch_timeout() - Handle exchange timer expiration
762  * @work: The work_struct identifying the exchange that timed out
772 	FC_EXCH_DBG(ep, "Exchange timed out state %x\n", ep->state);  in fc_exch_timeout()
806  * fc_exch_em_alloc() - Allocate an exchange from a specified EM.
807  * @lport: The local port that the exchange is for
808  * @mp:	   The exchange manager that will allocate the exchange
820 	/* allocate memory for exchange */  in fc_exch_em_alloc()
873 	 *  update exchange  in fc_exch_em_alloc()
895  * fc_exch_alloc() - Allocate an exchange from an EM on a
897  * @lport: The local port that will own the exchange
898  * @fp:	   The FC frame that the exchange will be for
900  * This function walks the list of exchange manager(EM)
901  * anchors to select an EM for a new exchange allocation. The
922  * fc_exch_find() - Lookup and hold an exchange
923  * @mp:	 The exchange manager to lookup the exchange from
924  * @xid: The XID of the exchange to look up
961  * fc_exch_done() - Indicate that an exchange/sequence tuple is complete and
983  * fc_exch_resp() - Allocate a new exchange for a response frame
984  * @lport: The local port that the exchange was for
985  * @mp:	   The exchange manager to allocate the exchange from
1002 		 * Set EX_CTX indicating we're responding on this exchange.  in fc_exch_resp()
1012 		 * Allocated exchange has placed the XID in the  in fc_exch_resp()
1032  * @mp:	   The Exchange Manager to lookup the exchange from
1053 	 * Lookup or create the exchange if we will be creating the sequence.  in fc_seq_lookup_recip()
1084 		 * new sequence - find the exchange  in fc_seq_lookup_recip()
1108 	 * At this point, we have the exchange held.  in fc_seq_lookup_recip()
1122 				 * frame of sequence exchange. This is needed  in fc_seq_lookup_recip()
1163  * @mp:	   The Exchange Manager to lookup the exchange from
1198  * fc_exch_set_addr() - Set the source and destination IDs for an exchange
1199  * @ep:	     The exchange to set the addresses for
1203  * Note this must be done before the first sequence of the exchange is sent.
1220  *			   the existing sequence/exchange.
1250  * fc_seq_send_last() - Send a sequence that is the last in the exchange
1404  * @ep:	   The exchange the abort was on
1409  * exchange abort, ignoring the parameter.
1431 		FC_EXCH_DBG(ep, "exch: ABTS rejected, exchange complete\n");  in fc_exch_recv_abts()
1466  * fc_seq_assign() - Assign exchange and sequence for incoming request
1471  * A reference will be held on the exchange/sequence for the caller, which
1503  * @mp:	   The EM that the exchange is on
1506  * This is used when the other end is originating the exchange
1518 	 * problem now that we know a new exchange needs to be allocated  in fc_exch_recv_req()
1530 	 * If the RX_ID is 0xffff, don't allocate an exchange.  in fc_exch_recv_req()
1567  *			     response to our initial exchange
1568  * @mp: The EM that the exchange is on
1662  * @mp: The EM that the exchange is on
1681  * @ep: The exchange that the frame is on
1684  * This response would be to an ABTS cancelling an exchange or sequence.
1701 		FC_EXCH_DBG(ep, "Exchange timer canceled due to ABTS response\n");  in fc_exch_abts_resp()
1758  * @mp: The EM that the exchange is on
1762  * We may be either the originator or recipient of the exchange.
1886  * fc_exch_reset() - Reset an exchange
1887  * @ep: The exchange to be reset
1923  * fc_exch_pool_reset() - Reset a per cpu exchange pool
1924  * @lport: The local port that the exchange pool is on
1925  * @pool:  The exchange pool to be reset
1994  * fc_exch_lookup() - find an exchange
1996  * @xid: The exchange ID
1998  * Returns exchange pointer with hold for caller, or NULL if not found.
2011  * fc_exch_els_rec() - Handler for ELS REC (Read Exchange Concise) requests
2097  * @arg: The exchange that the RRQ is on
2139  * fc_exch_seq_send() - Send a frame using a new exchange and sequence
2143  * @destructor: The destructor for the exchange
2145  * @timer_msec: The timeout period for the exchange
2147  * The exchange response handler is set in this routine to resp()
2149  * occurs or if a response frame is received for the exchange. The
2153  * The exchange destructor handler is also set in this routine.
2154  * The destructor handler is invoked by EM layer when exchange
2156  * resources along with exchange free.
2160  * The timeout value (in msec) for an exchange is set if non zero
2162  * it fires or when the exchange is done. The exchange timeout handler
2238  * @ep: The exchange to send the RRQ on
2241  * the exchange and the seq_cnt range.
2296 	struct fc_exch *ep = NULL;	/* request or subject exchange */  in fc_exch_els_rrq()
2309 	 * lookup subject exchange.  in fc_exch_els_rrq()
2359  * @lport: The local port to update exchange manager stats
2383  * fc_exch_mgr_add() - Add an exchange manager to a local port's list of EMs
2384  * @lport: The local port to add the exchange manager to
2385  * @mp:	   The exchange manager to be added to the local port
2408  * fc_exch_mgr_destroy() - Destroy an exchange manager
2422  * @ema: The exchange manager anchor identifying the EM to be deleted
2434  * fc_exch_mgr_list_clone() - Share all exchange manager objects
2435  * @src: Source lport to clone exchange managers from
2436  * @dst: New lport that takes references to all the exchange managers
2455  * fc_exch_mgr_alloc() - Allocate an exchange manager
2509 	 * Setup per cpu exch pool with entire exchange id range equally  in fc_exch_mgr_alloc()
2554  * fc_exch_mgr_free() - Free all exchange managers on a local port
2568  * fc_find_ema() - Lookup and return appropriate Exchange Manager Anchor depending
2619 		FC_LPORT_DBG(lport, "Unable to find Exchange Manager Anchor,"  in fc_exch_recv()
2657  * fc_exch_init() - Initialize the exchange layer for a local port
2658  * @lport: The local port to initialize the exchange layer for
2670  * fc_setup_exch_mgr() - Setup an exchange manager
2688 	 * to exchange id's lower bits such that all incoming  in fc_setup_exch_mgr()
2689 	 * frames of an exchange gets delivered to the same  in fc_setup_exch_mgr()
2690 	 * cpu on which exchange originated by simple bitwise  in fc_setup_exch_mgr()
2691 	 * AND operation between fc_cpu_mask and exchange id.  in fc_setup_exch_mgr()
2706  * fc_destroy_exch_mgr() - Destroy an exchange manager