[SCSI] libfc: Enhanced exchange ID selection mechanism and fix related EMA selection...

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: Kiran Patil <kiran.patil@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index a3d6402..08bf5fa 100644 (file)
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -2281,16 +2281,45 @@ 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
- * @fp:           The received frame
+ * @fp:        The received frame
  */
 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);
-                       fc_frame_free(fp);
-                       return;
-               }
-       } else
-               ema = list_entry(lport->ema_list.prev, typeof(*ema), ema_list);
+       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;
+       }
 
        /*
         * If frame is marked invalid, just drop it.