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Commit 6c8cc1c0 authored by Kiran Patil's avatar Kiran Patil Committed by James Bottomley
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[SCSI] libfc: Enhanced exchange ID selection mechanism and fix related EMA selection logic. 



Problem:

In case of exchange responder case, EMA selection was defaulted to the
last EMA from EMA list (lport.ema_list).  If exchange ID is selected
from offload pool and not setup DDP, resulting into incorrect
selection of EMA, and eventually dropping the packet because unable to
find exchange.

Fix:

Enhanced the exchange ID selection (depending upon request type and
exchange responder) Made necessary enhancement in EMA selection
algorithm.

Signed-off-by: default avatarKiran Patil <kiran.patil@intel.com>
Signed-off-by: default avatarRobert Love <robert.w.love@intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
parent 62bdb645

drivers/scsi/libfc/fc_exch.c

+43 −21
Original line number Diff line number Diff line
@@ -2280,6 +2280,36 @@ void fc_exch_mgr_free(struct fc_lport *lport) 
}

EXPORT_SYMBOL(fc_exch_mgr_free);



/**

 * fc_find_ema() - Lookup and return appropriate Exchange Manager Anchor depending

 * upon 'xid'.

 * @f_ctl: f_ctl

 * @lport: The local port the frame was received on

 * @fh: The received frame header

 */

static struct fc_exch_mgr_anchor *fc_find_ema(u32 f_ctl,

					      struct fc_lport *lport,

					      struct fc_frame_header *fh)

{

	struct fc_exch_mgr_anchor *ema;

	u16 xid;



	if (f_ctl & FC_FC_EX_CTX)

		xid = ntohs(fh->fh_ox_id);

	else {

		xid = ntohs(fh->fh_rx_id);

		if (xid == FC_XID_UNKNOWN)

			return list_entry(lport->ema_list.prev,

					  typeof(*ema), ema_list);

	}



	list_for_each_entry(ema, &lport->ema_list, ema_list) {

		if ((xid >= ema->mp->min_xid) &&

		    (xid <= ema->mp->max_xid))

			return ema;

	}

	return NULL;

}

/**

 * fc_exch_recv() - Handler for received frames

 * @lport: The local port the frame was received on
@@ -2289,8 +2319,7 @@ void fc_exch_recv(struct fc_lport *lport, struct fc_frame *fp) 
{

	struct fc_frame_header *fh = fc_frame_header_get(fp);

	struct fc_exch_mgr_anchor *ema;

	u32 f_ctl, found = 0;

	u16 oxid;

	u32 f_ctl;



	/* lport lock ? */

	if (!lport || lport->state == LPORT_ST_DISABLED) {
@@ -2301,24 +2330,17 @@ void fc_exch_recv(struct fc_lport *lport, struct fc_frame *fp) 
	}



	f_ctl = ntoh24(fh->fh_f_ctl);

	oxid = ntohs(fh->fh_ox_id);

	if (f_ctl & FC_FC_EX_CTX) {

		list_for_each_entry(ema, &lport->ema_list, ema_list) {

			if ((oxid >= ema->mp->min_xid) &&

			    (oxid <= ema->mp->max_xid)) {

				found = 1;

				break;

			}

		}



		if (!found) {

			FC_LPORT_DBG(lport, "Received response for out "

				     "of range oxid:%hx\n", oxid);

	ema = fc_find_ema(f_ctl, lport, fh);

	if (!ema) {

		FC_LPORT_DBG(lport, "Unable to find Exchange Manager Anchor,"

				    "fc_ctl <0x%x>, xid <0x%x>\n",

				     f_ctl,

				     (f_ctl & FC_FC_EX_CTX) ?

				     ntohs(fh->fh_ox_id) :

				     ntohs(fh->fh_rx_id));

		fc_frame_free(fp);

		return;

	}

	} else

		ema = list_entry(lport->ema_list.prev, typeof(*ema), ema_list);



	/*

	 * If frame is marked invalid, just drop it.