IB/iser: Make fastreg pool cache friendly

Memory regions are resources that are saved
in the device caches. Increase the probability for
a cache hit by adding the MRU descriptor to pool
head.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/iser/iser_memory.c

@@ -63,7 +63,7 @@ iser_reg_desc_put(struct ib_conn *ib_conn,
 	unsigned long flags;
 
 	spin_lock_irqsave(&ib_conn->lock, flags);
-	list_add_tail(&desc->list, &ib_conn->fastreg.pool);
+	list_add(&desc->list, &ib_conn->fastreg.pool);
 	spin_unlock_irqrestore(&ib_conn->lock, flags);
 }