On Monday 26 October 2009 20:37:33 Michael Buesch wrote:
> Ok, it just turns out this actually is a driver bug.
> Thanks to Johannes Berg for tracking it down.
>
> I think it's caused by the DMA bouncebuffer stuff that does not copy the skb->cb
> and does not adjust the "tx-info" pointer.
> I wonder why this didn't blow up easlier, because this bug is there since mac80211
> switched to using the CB.
>
> Here's a completely untested patch.
Here's a new version of the patch that also fixes queue mapping bugs:
---
drivers/net/wireless/b43/dma.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
--- wireless-testing.orig/drivers/net/wireless/b43/dma.c
+++ wireless-testing/drivers/net/wireless/b43/dma.c
@@ -1157,8 +1157,9 @@ struct b43_dmaring *parse_cookie(struct
}
static int dma_tx_fragment(struct b43_dmaring *ring,
- struct sk_buff *skb)
+ struct sk_buff **in_skb)
{
+ struct sk_buff *skb = *in_skb;
const struct b43_dma_ops *ops = ring->ops;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
u8 *header;
@@ -1224,8 +1225,14 @@ static int dma_tx_fragment(struct b43_dm
}
memcpy(skb_put(bounce_skb, skb->len), skb->data, skb->len);
+ memcpy(bounce_skb->cb, skb->cb, sizeof(skb->cb));
+ bounce_skb->dev = skb->dev;
+ skb_set_queue_mapping(bounce_skb, skb_get_queue_mapping(skb));
+ info = IEEE80211_SKB_CB(bounce_skb);
+
dev_kfree_skb_any(skb);
skb = bounce_skb;
+ *in_skb = bounce_skb;
meta->skb = skb;
meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
if (b43_dma_mapping_error(ring, meta->dmaaddr, skb->len, 1)) {
@@ -1355,7 +1362,11 @@ int b43_dma_tx(struct b43_wldev *dev, st
* static, so we don't need to store it per frame. */
ring->queue_prio = skb_get_queue_mapping(skb);
- err = dma_tx_fragment(ring, skb);
+ /* dma_tx_fragment might reallocate the skb, so invalidate pointers pointing
+ * into the skb data or cb now. */
+ hdr = NULL;
+ info = NULL;
+ err = dma_tx_fragment(ring, &skb);
if (unlikely(err == -ENOKEY)) {
/* Drop this packet, as we don't have the encryption key
* anymore and must not transmit it unencrypted. */
--
Greetings, Michael.
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