1 files changed, 40 insertions, 10 deletions

diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index e228c1d..eae680b 100644
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -555,11 +555,32 @@ address_error:
 	return 1;
 }
 
+static bool b43_rx_buffer_is_poisoned(struct b43_dmaring *ring, struct sk_buff *skb)
+{
+	unsigned char *f = skb->data + ring->frameoffset;
+
+	return ((f[0] & f[1] & f[2] & f[3] & f[4] & f[5] & f[6] & f[7]) == 0xFF);
+}
+
+static void b43_poison_rx_buffer(struct b43_dmaring *ring, struct sk_buff *skb)
+{
+	struct b43_rxhdr_fw4 *rxhdr;
+	unsigned char *frame;
+
+	/* This poisons the RX buffer to detect DMA failures. */
+
+	rxhdr = (struct b43_rxhdr_fw4 *)(skb->data);
+	rxhdr->frame_len = 0;
+
+	B43_WARN_ON(ring->rx_buffersize < ring->frameoffset + sizeof(struct b43_plcp_hdr6) + 2);
+	frame = skb->data + ring->frameoffset;
+	memset(frame, 0xFF, sizeof(struct b43_plcp_hdr6) + 2 /* padding */);
+}
+
 static int setup_rx_descbuffer(struct b43_dmaring *ring,
 			       struct b43_dmadesc_generic *desc,
 			       struct b43_dmadesc_meta *meta, gfp_t gfp_flags)
 {
-	struct b43_rxhdr_fw4 *rxhdr;
 	dma_addr_t dmaaddr;
 	struct sk_buff *skb;
 
@@ -568,6 +589,7 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring,
 	skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags);
 	if (unlikely(!skb))
 		return -ENOMEM;
+	b43_poison_rx_buffer(ring, skb);
 	dmaaddr = map_descbuffer(ring, skb->data, ring->rx_buffersize, 0);
 	if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize, 0)) {
 		/* ugh. try to realloc in zone_dma */
@@ -578,6 +600,7 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring,
 		skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags);
 		if (unlikely(!skb))
 			return -ENOMEM;
+		b43_poison_rx_buffer(ring, skb);
 		dmaaddr = map_descbuffer(ring, skb->data,
 					 ring->rx_buffersize, 0);
 		if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize, 0)) {
@@ -592,9 +615,6 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring,
 	ring->ops->fill_descriptor(ring, desc, dmaaddr,
 				   ring->rx_buffersize, 0, 0, 0);
 
-	rxhdr = (struct b43_rxhdr_fw4 *)(skb->data);
-	rxhdr->frame_len = 0;
-
 	return 0;
 }
 
@@ -1483,12 +1503,17 @@ static void dma_rx(struct b43_dmaring *ring, int *slot)
 			len = le16_to_cpu(rxhdr->frame_len);
 		} while (len == 0 && i++ < 5);
 		if (unlikely(len == 0)) {
-			/* recycle the descriptor buffer. */
-			sync_descbuffer_for_device(ring, meta->dmaaddr,
-						   ring->rx_buffersize);
-			goto drop;
+			dmaaddr = meta->dmaaddr;
+			goto drop_recycle_buffer;
 		}
 	}
+	if (unlikely(b43_rx_buffer_is_poisoned(ring, skb))) {
+		/* Something went wrong with the DMA.
+		 * The device did not touch the buffer and did not overwrite the poison. */
+		b43dbg(ring->dev->wl, "DMA RX: Dropping poisoned buffer.\n");
+		dmaaddr = meta->dmaaddr;
+		goto drop_recycle_buffer;
+	}
 	if (unlikely(len > ring->rx_buffersize)) {
 		/* The data did not fit into one descriptor buffer
 		 * and is split over multiple buffers.
@@ -1501,6 +1526,7 @@ static void dma_rx(struct b43_dmaring *ring, int *slot)
 		while (1) {
 			desc = ops->idx2desc(ring, *slot, &meta);
 			/* recycle the descriptor buffer. */
+			b43_poison_rx_buffer(ring, meta->skb);
 			sync_descbuffer_for_device(ring, meta->dmaaddr,
 						   ring->rx_buffersize);
 			*slot = next_slot(ring, *slot);
@@ -1519,8 +1545,7 @@ static void dma_rx(struct b43_dmaring *ring, int *slot)
 	err = setup_rx_descbuffer(ring, desc, meta, GFP_ATOMIC);
 	if (unlikely(err)) {
 		b43dbg(ring->dev->wl, "DMA RX: setup_rx_descbuffer() failed\n");
-		sync_descbuffer_for_device(ring, dmaaddr, ring->rx_buffersize);
-		goto drop;
+		goto drop_recycle_buffer;
 	}
 
 	unmap_descbuffer(ring, dmaaddr, ring->rx_buffersize, 0);
@@ -1530,6 +1555,11 @@ static void dma_rx(struct b43_dmaring *ring, int *slot)
 	b43_rx(ring->dev, skb, rxhdr);
 drop:
 	return;
+
+drop_recycle_buffer:
+	/* Poison and recycle the RX buffer. */
+	b43_poison_rx_buffer(ring, skb);
+	sync_descbuffer_for_device(ring, dmaaddr, ring->rx_buffersize);
 }
 
 void b43_dma_rx(struct b43_dmaring *ring)