[PATCH net-next 2/5] dpaa2-switch: fix the error path in dpaa2_switch_rx()

[Ioana Ciornei]

In case of an error in dpaa2_switch_rx(), the dpaa2_switch_free_fd()
function is called in order to free the FD. This is incorrect since the
dpaa2_switch_free_fd() is intended to be used on Tx frame descriptors,
meaning that it expects in the software annotation area of the FD data
to find a valid skb pointer on which to call dev_kfree_skb().

Fix this by extracting the dma_unmap_page() from
dpaa2_switch_build_linear_skb() directly into the dpaa2_switch_rx()
function. This allows us to directly use free_pages() in case of an
error before an SKB was created and kfree_skb() afterwards.

Signed-off-by: Ioana Ciornei <ioana.ciornei@xxxxxxx>
---
 .../ethernet/freescale/dpaa2/dpaa2-switch.c   | 23 ++++++++++---------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
index 782fef26b78e..53a32b21b959 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
@@ -2429,18 +2429,13 @@ static int dpaa2_switch_port_blocking_event(struct notifier_block *nb,
 
 /* Build a linear skb based on a single-buffer frame descriptor */
 static struct sk_buff *dpaa2_switch_build_linear_skb(struct ethsw_core *ethsw,
-						     const struct dpaa2_fd *fd)
+						     const struct dpaa2_fd *fd,
+						     void *fd_vaddr)
 {
 	u16 fd_offset = dpaa2_fd_get_offset(fd);
-	dma_addr_t addr = dpaa2_fd_get_addr(fd);
 	u32 fd_length = dpaa2_fd_get_len(fd);
 	struct device *dev = ethsw->dev;
 	struct sk_buff *skb = NULL;
-	void *fd_vaddr;
-
-	fd_vaddr = dpaa2_iova_to_virt(ethsw->iommu_domain, addr);
-	dma_unmap_page(dev, addr, DPAA2_SWITCH_RX_BUF_SIZE,
-		       DMA_FROM_DEVICE);
 
 	skb = build_skb(fd_vaddr, DPAA2_SWITCH_RX_BUF_SIZE +
 			SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
@@ -2466,6 +2461,7 @@ static void dpaa2_switch_tx_conf(struct dpaa2_switch_fq *fq,
 static void dpaa2_switch_rx(struct dpaa2_switch_fq *fq,
 			    const struct dpaa2_fd *fd)
 {
+	dma_addr_t addr = dpaa2_fd_get_addr(fd);
 	struct ethsw_core *ethsw = fq->ethsw;
 	struct ethsw_port_priv *port_priv;
 	struct net_device *netdev;
@@ -2473,10 +2469,14 @@ static void dpaa2_switch_rx(struct dpaa2_switch_fq *fq,
 	struct sk_buff *skb;
 	u16 vlan_tci, vid;
 	int if_id, err;
+	void *vaddr;
+
+	vaddr = dpaa2_iova_to_virt(ethsw->iommu_domain, addr);
+	dma_unmap_page(ethsw->dev, addr, DPAA2_SWITCH_RX_BUF_SIZE,
+		       DMA_FROM_DEVICE);
 
 	/* get switch ingress interface ID */
 	if_id = upper_32_bits(dpaa2_fd_get_flc(fd)) & 0x0000FFFF;
-
 	if (if_id >= ethsw->sw_attr.num_ifs) {
 		dev_err(ethsw->dev, "Frame received from unknown interface!\n");
 		goto err_free_fd;
@@ -2492,7 +2492,7 @@ static void dpaa2_switch_rx(struct dpaa2_switch_fq *fq,
 		}
 	}
 
-	skb = dpaa2_switch_build_linear_skb(ethsw, fd);
+	skb = dpaa2_switch_build_linear_skb(ethsw, fd, vaddr);
 	if (unlikely(!skb))
 		goto err_free_fd;
 
@@ -2510,7 +2510,8 @@ static void dpaa2_switch_rx(struct dpaa2_switch_fq *fq,
 		err = __skb_vlan_pop(skb, &vlan_tci);
 		if (err) {
 			dev_info(ethsw->dev, "__skb_vlan_pop() returned %d", err);
-			goto err_free_fd;
+			kfree_skb(skb);
+			return;
 		}
 	}
 
@@ -2525,7 +2526,7 @@ static void dpaa2_switch_rx(struct dpaa2_switch_fq *fq,
 	return;
 
 err_free_fd:
-	dpaa2_switch_free_fd(ethsw, fd);
+	free_pages((unsigned long)vaddr, 0);
 }
 
 static void dpaa2_switch_detect_features(struct ethsw_core *ethsw)
-- 
2.25.1