NTB: Link toggle memory leak

Each link-up will allocate a new NTB receive buffer when the NTB
properties are negotiated with the remote system.  These allocations did
not check for existing buffers and thus did not free them.  Now, the
driver will check for an existing buffer and free it if not of the
correct size, before trying to alloc a new one.
Signed-off-by: NJon Mason <jon.mason@intel.com>

drivers/ntb/ntb_transport.c

@@ -507,17 +507,37 @@ static void ntb_transport_setup_qp_mw(struct ntb_transport *nt,
 	qp->tx_pkts = 0;
 }
 
+static void ntb_free_mw(struct ntb_transport *nt, int num_mw)
+{
+	struct ntb_transport_mw *mw = &nt->mw[num_mw];
+	struct pci_dev *pdev = ntb_query_pdev(nt->ndev);
+
+	if (!mw->virt_addr)
+		return;
+
+	dma_free_coherent(&pdev->dev, mw->size, mw->virt_addr, mw->dma_addr);
+	mw->virt_addr = NULL;
+}
+
 static int ntb_set_mw(struct ntb_transport *nt, int num_mw, unsigned int size)
 {
 	struct ntb_transport_mw *mw = &nt->mw[num_mw];
 	struct pci_dev *pdev = ntb_query_pdev(nt->ndev);
 
+	/* No need to re-setup */
+	if (mw->size == ALIGN(size, 4096))
+		return 0;
+
+	if (mw->size != 0)
+		ntb_free_mw(nt, num_mw);
+
 	/* Alloc memory for receiving data.  Must be 4k aligned */
 	mw->size = ALIGN(size, 4096);
 
 	mw->virt_addr = dma_alloc_coherent(&pdev->dev, mw->size, &mw->dma_addr,
 					   GFP_KERNEL);
 	if (!mw->virt_addr) {
+		mw->size = 0;
 		dev_err(&pdev->dev, "Unable to allocate MW buffer of size %d\n",
 		       (int) mw->size);
 		return -ENOMEM;
@@ -529,18 +549,6 @@ static int ntb_set_mw(struct ntb_transport *nt, int num_mw, unsigned int size)
 	return 0;
 }
 
-static void ntb_free_mw(struct ntb_transport *nt, int num_mw)
-{
-	struct ntb_transport_mw *mw = &nt->mw[num_mw];
-	struct pci_dev *pdev = ntb_query_pdev(nt->ndev);
-
-	if (!mw->virt_addr)
-		return;
-
-	dma_free_coherent(&pdev->dev, mw->size, mw->virt_addr, mw->dma_addr);
-	mw->virt_addr = NULL;
-}
-
 static void ntb_qp_link_cleanup(struct work_struct *work)
 {
 	struct ntb_transport_qp *qp = container_of(work,