[PATCH net v4 1/2] net/ps3_gelic_net: Fix RX sk_buff length

[Geoff Levand <geoff@infradead.org>]

The Gelic Ethernet device needs to have the RX sk_buffs aligned to
GELIC_NET_RXBUF_ALIGN and the length of the RX sk_buffs must be a multiple of
GELIC_NET_RXBUF_ALIGN.

The current Gelic Ethernet driver was not allocating sk_buffs large enough to
allow for this alignment.

Fixes various randomly occurring runtime network errors.

Fixes: 02c1889166b4 (ps3: gigabit ethernet driver for PS3, take3)
Signed-off-by: Geoff Levand <geoff@infradead.org>
---
 drivers/net/ethernet/toshiba/ps3_gelic_net.c | 56 ++++++++++++--------
 1 file changed, 34 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/toshiba/ps3_gelic_net.c b/drivers/net/ethernet/toshiba/ps3_gelic_net.c
index cf8de8a7a8a1..7a8b5e1e77a6 100644
--- a/drivers/net/ethernet/toshiba/ps3_gelic_net.c
+++ b/drivers/net/ethernet/toshiba/ps3_gelic_net.c
@@ -365,51 +365,63 @@ static int gelic_card_init_chain(struct gelic_card *card,
  *
  * allocates a new rx skb, iommu-maps it and attaches it to the descriptor.
  * Activate the descriptor state-wise
+ *
+ * Gelic RX sk_buffs must be aligned to GELIC_NET_RXBUF_ALIGN and the length
+ * must be a multiple of GELIC_NET_RXBUF_ALIGN.
  */
 static int gelic_descr_prepare_rx(struct gelic_card *card,
 				  struct gelic_descr *descr)
 {
-	int offset;
-	unsigned int bufsize;
+	struct device *dev = ctodev(card);
+	struct {
+		unsigned int total_bytes;
+		unsigned int offset;
+	} aligned_buf;
+	dma_addr_t cpu_addr;
 
 	if (gelic_descr_get_status(descr) !=  GELIC_DESCR_DMA_NOT_IN_USE)
 		dev_info(ctodev(card), "%s: ERROR status\n", __func__);
-	/* we need to round up the buffer size to a multiple of 128 */
-	bufsize = ALIGN(GELIC_NET_MAX_MTU, GELIC_NET_RXBUF_ALIGN);
 
-	/* and we need to have it 128 byte aligned, therefore we allocate a
-	 * bit more */
-	descr->skb = dev_alloc_skb(bufsize + GELIC_NET_RXBUF_ALIGN - 1);
+	aligned_buf.total_bytes = (GELIC_NET_RXBUF_ALIGN - 1) +
+		GELIC_NET_MAX_MTU + (GELIC_NET_RXBUF_ALIGN - 1);
+
+	descr->skb = dev_alloc_skb(aligned_buf.total_bytes);
+
 	if (!descr->skb) {
-		descr->buf_addr = 0; /* tell DMAC don't touch memory */
+		descr->buf_addr = 0;
 		return -ENOMEM;
 	}
-	descr->buf_size = cpu_to_be32(bufsize);
+
+	aligned_buf.offset =
+		PTR_ALIGN(descr->skb->data, GELIC_NET_RXBUF_ALIGN) -
+			descr->skb->data;
+
+	descr->buf_size = ALIGN(GELIC_NET_MAX_MTU, GELIC_NET_RXBUF_ALIGN);
 	descr->dmac_cmd_status = 0;
 	descr->result_size = 0;
 	descr->valid_size = 0;
 	descr->data_error = 0;
 
-	offset = ((unsigned long)descr->skb->data) &
-		(GELIC_NET_RXBUF_ALIGN - 1);
-	if (offset)
-		skb_reserve(descr->skb, GELIC_NET_RXBUF_ALIGN - offset);
-	/* io-mmu-map the skb */
-	descr->buf_addr = cpu_to_be32(dma_map_single(ctodev(card),
-						     descr->skb->data,
-						     GELIC_NET_MAX_MTU,
-						     DMA_FROM_DEVICE));
+	skb_reserve(descr->skb, aligned_buf.offset);
+
+	cpu_addr = dma_map_single(dev, descr->skb->data, descr->buf_size,
+		DMA_FROM_DEVICE);
+
+	descr->buf_addr = cpu_to_be32(cpu_addr);
+
 	if (!descr->buf_addr) {
 		dev_kfree_skb_any(descr->skb);
+		descr->buf_addr = 0;
+		descr->buf_size = 0;
 		descr->skb = NULL;
-		dev_info(ctodev(card),
+		dev_info(dev,
 			 "%s:Could not iommu-map rx buffer\n", __func__);
 		gelic_descr_set_status(descr, GELIC_DESCR_DMA_NOT_IN_USE);
 		return -ENOMEM;
-	} else {
-		gelic_descr_set_status(descr, GELIC_DESCR_DMA_CARDOWNED);
-		return 0;
 	}
+
+	gelic_descr_set_status(descr, GELIC_DESCR_DMA_CARDOWNED);
+	return 0;
 }
 
 /**
-- 
2.34.1