RDMA/cxgb4: Save the correct map length for fast_reg_page_lists

We cannot save the mapped length using the rdma max_page_list_len field
of the ib_fast_reg_page_list struct because the core code uses it.  This
results in an incorrect unmap of the page list in c4iw_free_fastreg_pbl().

I found this with dma mapping debugging enabled in the kernel.  The
fix is to save the length in the c4iw_fr_page_list struct.
Signed-off-by: NSteve Wise <swise@opengridcomputing.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

drivers/infiniband/hw/cxgb4/iw_cxgb4.h

@@ -369,6 +369,7 @@ struct c4iw_fr_page_list {
 	DEFINE_DMA_UNMAP_ADDR(mapping);
 	dma_addr_t dma_addr;
 	struct c4iw_dev *dev;
+	int pll_len;
 };
 
 static inline struct c4iw_fr_page_list *to_c4iw_fr_page_list(

drivers/infiniband/hw/cxgb4/mem.c

@@ -903,7 +903,11 @@ struct ib_fast_reg_page_list *c4iw_alloc_fastreg_pbl(struct ib_device *device,
 	dma_unmap_addr_set(c4pl, mapping, dma_addr);
 	c4pl->dma_addr = dma_addr;
 	c4pl->dev = dev;
-	c4pl->ibpl.max_page_list_len = pll_len;
+	c4pl->pll_len = pll_len;
+
+	PDBG("%s c4pl %p pll_len %u page_list %p dma_addr %pad\n",
+	     __func__, c4pl, c4pl->pll_len, c4pl->ibpl.page_list,
+	     &c4pl->dma_addr);
 
 	return &c4pl->ibpl;
 }
@@ -912,8 +916,12 @@ void c4iw_free_fastreg_pbl(struct ib_fast_reg_page_list *ibpl)
 {
 	struct c4iw_fr_page_list *c4pl = to_c4iw_fr_page_list(ibpl);
 
+	PDBG("%s c4pl %p pll_len %u page_list %p dma_addr %pad\n",
+	     __func__, c4pl, c4pl->pll_len, c4pl->ibpl.page_list,
+	     &c4pl->dma_addr);
+
 	dma_free_coherent(&c4pl->dev->rdev.lldi.pdev->dev,
-			  c4pl->ibpl.max_page_list_len,
+			  c4pl->pll_len,
 			  c4pl->ibpl.page_list, dma_unmap_addr(c4pl, mapping));
 	kfree(c4pl);
 }