1 files changed, 40 insertions, 10 deletions

diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index e228c1de6e11..eae680b53052 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)