1 files changed, 18 insertions, 76 deletions

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index 324589a5cc03..11ddd115efb6 100644
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -58,7 +58,7 @@ struct fc_exch_mgr {
         struct kref     kref;           /* exchange mgr reference count */
         spinlock_t      em_lock;        /* exchange manager lock,
                                            must be taken before ex_lock */
-        u16             last_xid;       /* last allocated exchange ID */
+        u16             next_xid;       /* next possible free exchange ID */
         u16             min_xid;        /* min exchange ID */
         u16             max_xid;        /* max exchange ID */
         u16             max_read;       /* max exchange ID for read */
@@ -464,68 +464,21 @@ static struct fc_seq *fc_seq_alloc(struct fc_exch *ep, u8 seq_id)
         return sp;
 }
 
-/*
- * fc_em_alloc_xid - returns an xid based on request type
- * @lp : ptr to associated lport
- * @fp : ptr to the assocated frame
- *
- * check the associated fc_fsp_pkt to get scsi command type and
- * command direction to decide from which range this exch id
- * will be allocated from.
- *
- * Returns : 0 or an valid xid
- */
-static u16 fc_em_alloc_xid(struct fc_exch_mgr *mp, const struct fc_frame *fp)
-{
-        u16 xid, min, max;
-        u16 *plast;
-        struct fc_exch *ep = NULL;
-
-        if (mp->max_read) {
-                if (fc_fcp_is_read(fr_fsp(fp))) {
-                        min = mp->min_xid;
-                        max = mp->max_read;
-                        plast = &mp->last_read;
-                } else {
-                        min = mp->max_read + 1;
-                        max = mp->max_xid;
-                        plast = &mp->last_xid;
-                }
-        } else {
-                min = mp->min_xid;
-                max = mp->max_xid;
-                plast = &mp->last_xid;
-        }
-        xid = *plast;
-        do {
-                xid = (xid == max) ? min : xid + 1;
-                ep = mp->exches[xid - mp->min_xid];
-        } while ((ep != NULL) && (xid != *plast));
-
-        if (unlikely(ep))
-                xid = 0;
-        else
-                *plast = xid;
-
-        return xid;
-}
-
 /**
  * fc_exch_em_alloc() - allocate an exchange from a specified EM.
  * @lport:      ptr to the local port
  * @mp:         ptr to the exchange manager
- * @fp:         ptr to the FC frame
- * @xid:        input xid
  *
- * if xid is supplied zero then assign next free exchange ID
- * from exchange manager, otherwise use supplied xid.
- * Returns with exch lock held.
+ * Returns pointer to allocated fc_exch with exch lock held.
  */
 static struct fc_exch *fc_exch_em_alloc(struct fc_lport *lport,
-                                        struct fc_exch_mgr *mp,
-                                        struct fc_frame *fp, u16 xid)
+                                        struct fc_exch_mgr *mp)
 {
         struct fc_exch *ep;
+        u16 min, max, xid;
+
+        min = mp->min_xid;
+        max = mp->max_xid;
 
         /* allocate memory for exchange */
         ep = mempool_alloc(mp->ep_pool, GFP_ATOMIC);
@@ -536,15 +489,14 @@ static struct fc_exch *fc_exch_em_alloc(struct fc_lport *lport,
         memset(ep, 0, sizeof(*ep));
 
         spin_lock_bh(&mp->em_lock);
-        /* alloc xid if input xid 0 */
-        if (!xid) {
-                /* alloc a new xid */
-                xid = fc_em_alloc_xid(mp, fp);
-                if (!xid) {
-                        printk(KERN_WARNING "libfc: Failed to allocate an exhange\n");
+        xid = mp->next_xid;
+        /* alloc a new xid */
+        while (mp->exches[xid - min]) {
+                xid = (xid == max) ? min : xid + 1;
+                if (xid == mp->next_xid)
                         goto err;
-                }
         }
+        mp->next_xid = (xid == max) ? min : xid + 1;
 
         fc_exch_hold(ep);       /* hold for exch in mp */
         spin_lock_init(&ep->ex_lock);
@@ -597,7 +549,7 @@ struct fc_exch *fc_exch_alloc(struct fc_lport *lport, struct fc_frame *fp)
 
         list_for_each_entry(ema, &lport->ema_list, ema_list) {
                 if (!ema->match || ema->match(fp)) {
-                        ep = fc_exch_em_alloc(lport, ema->mp, fp, 0);
+                        ep = fc_exch_em_alloc(lport, ema->mp);
                         if (ep)
                                 return ep;
                 }
@@ -1817,7 +1769,7 @@ struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lp,
         struct fc_exch_mgr *mp;
         size_t len;
 
-        if (max_xid <= min_xid || min_xid == 0 || max_xid == FC_XID_UNKNOWN) {
+        if (max_xid <= min_xid || max_xid == FC_XID_UNKNOWN) {
                 FC_LPORT_DBG(lp, "Invalid min_xid 0x:%x and max_xid 0x:%x\n",
                              min_xid, max_xid);
                 return NULL;
@@ -1826,7 +1778,6 @@ struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lp,
         /*
          * Memory need for EM
          */
-#define xid_ok(i, m1, m2) (((i) >= (m1)) && ((i) <= (m2)))
         len = (max_xid - min_xid + 1) * (sizeof(struct fc_exch *));
         len += sizeof(struct fc_exch_mgr);
 
@@ -1840,17 +1791,7 @@ struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lp,
         /* adjust em exch xid range for offload */
         mp->min_xid = min_xid;
         mp->max_xid = max_xid;
-        mp->last_xid = min_xid - 1;
-        mp->max_read = 0;
-        mp->last_read = 0;
-        if (lp->lro_enabled && xid_ok(lp->lro_xid, min_xid, max_xid)) {
-                mp->max_read = lp->lro_xid;
-                mp->last_read = min_xid - 1;
-                mp->last_xid = mp->max_read;
-        } else {
-                /* disable lro if no xid control over read */
-                lp->lro_enabled = 0;
-        }
+        mp->next_xid = min_xid;
 
         INIT_LIST_HEAD(&mp->ex_list);
         spin_lock_init(&mp->em_lock);
@@ -1922,7 +1863,8 @@ struct fc_seq *fc_exch_seq_send(struct fc_lport *lp,
         fc_exch_setup_hdr(ep, fp, ep->f_ctl);
         sp->cnt++;
 
-        fc_fcp_ddp_setup(fr_fsp(fp), ep->xid);
+        if (ep->xid <= lp->lro_xid)
+                fc_fcp_ddp_setup(fr_fsp(fp), ep->xid);
 
         if (unlikely(lp->tt.frame_send(lp, fp)))
                 goto err;