diff options
author | Johannes Berg <johannes@sipsolutions.net> | 2008-11-18 01:47:21 +0100 |
---|---|---|
committer | John W. Linville <linville@tuxdriver.com> | 2008-11-18 17:26:26 -0500 |
commit | 4018517a1a69a85c3d61b20fa02f187b80773137 (patch) | |
tree | 08209615ff38b6c9e9af994c7360976e0a494ac6 /drivers | |
parent | 8e3bad65a59915f2ddc40f62a180ad81695d8440 (diff) | |
download | op-kernel-dev-4018517a1a69a85c3d61b20fa02f187b80773137.zip op-kernel-dev-4018517a1a69a85c3d61b20fa02f187b80773137.tar.gz |
iwlagn: fix RX skb alignment
So I dug deeper into the DMA problems I had with iwlagn and a kind soul
helped me in that he said something about pci-e alignment and mentioned
the iwl_rx_allocate function to check for crossing 4KB boundaries. Since
there's 8KB A-MPDU support, crossing 4k boundaries didn't seem like
something the device would fail with, but when I looked into the
function for a minute anyway I stumbled over this little gem:
BUG_ON(rxb->dma_addr & (~DMA_BIT_MASK(36) & 0xff));
Clearly, that is a totally bogus check, one would hope the compiler
removes it entirely. (Think about it)
After fixing it, I obviously ran into it, nothing guarantees the
alignment the way you want it, because of the way skbs and their
headroom are allocated. I won't explain that here nor double-check that
I'm right, that goes beyond what most of the CC'ed people care about.
So then I came up with the patch below, and so far my system has
survived minutes with 64K pages, when it would previously fail in
seconds. And I haven't seen a single instance of the TX bug either. But
when you see the patch it'll be pretty obvious to you why.
This should fix the following reported kernel bugs:
http://bugzilla.kernel.org/show_bug.cgi?id=11596
http://bugzilla.kernel.org/show_bug.cgi?id=11393
http://bugzilla.kernel.org/show_bug.cgi?id=11983
I haven't checked if there are any elsewhere, but I suppose RHBZ will
have a few instances too...
I'd like to ask anyone who is CC'ed (those are people I know ran into
the bug) to try this patch.
I am convinced that this patch is correct in spirit, but I haven't
understood why, for example, there are so many unmap calls. I'm not
entirely convinced that this is the only bug leading to the TX reply
errors.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/net/wireless/iwlwifi/iwl-agn.c | 6 | ||||
-rw-r--r-- | drivers/net/wireless/iwlwifi/iwl-dev.h | 3 | ||||
-rw-r--r-- | drivers/net/wireless/iwlwifi/iwl-rx.c | 26 |
3 files changed, 22 insertions, 13 deletions
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c index 6751bb2..444c5cc 100644 --- a/drivers/net/wireless/iwlwifi/iwl-agn.c +++ b/drivers/net/wireless/iwlwifi/iwl-agn.c @@ -1384,7 +1384,7 @@ void iwl_rx_handle(struct iwl_priv *priv) rxq->queue[i] = NULL; - pci_dma_sync_single_for_cpu(priv->pci_dev, rxb->dma_addr, + pci_dma_sync_single_for_cpu(priv->pci_dev, rxb->aligned_dma_addr, priv->hw_params.rx_buf_size, PCI_DMA_FROMDEVICE); pkt = (struct iwl_rx_packet *)rxb->skb->data; @@ -1436,8 +1436,8 @@ void iwl_rx_handle(struct iwl_priv *priv) rxb->skb = NULL; } - pci_unmap_single(priv->pci_dev, rxb->dma_addr, - priv->hw_params.rx_buf_size, + pci_unmap_single(priv->pci_dev, rxb->real_dma_addr, + priv->hw_params.rx_buf_size + 256, PCI_DMA_FROMDEVICE); spin_lock_irqsave(&rxq->lock, flags); list_add_tail(&rxb->list, &priv->rxq.rx_used); diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h index c018121..9966d4e 100644 --- a/drivers/net/wireless/iwlwifi/iwl-dev.h +++ b/drivers/net/wireless/iwlwifi/iwl-dev.h @@ -89,7 +89,8 @@ extern struct iwl_cfg iwl5100_abg_cfg; #define DEFAULT_LONG_RETRY_LIMIT 4U struct iwl_rx_mem_buffer { - dma_addr_t dma_addr; + dma_addr_t real_dma_addr; + dma_addr_t aligned_dma_addr; struct sk_buff *skb; struct list_head list; }; diff --git a/drivers/net/wireless/iwlwifi/iwl-rx.c b/drivers/net/wireless/iwlwifi/iwl-rx.c index 7cde9d7..0509c16 100644 --- a/drivers/net/wireless/iwlwifi/iwl-rx.c +++ b/drivers/net/wireless/iwlwifi/iwl-rx.c @@ -204,7 +204,7 @@ int iwl_rx_queue_restock(struct iwl_priv *priv) list_del(element); /* Point to Rx buffer via next RBD in circular buffer */ - rxq->bd[rxq->write] = iwl_dma_addr2rbd_ptr(priv, rxb->dma_addr); + rxq->bd[rxq->write] = iwl_dma_addr2rbd_ptr(priv, rxb->aligned_dma_addr); rxq->queue[rxq->write] = rxb; rxq->write = (rxq->write + 1) & RX_QUEUE_MASK; rxq->free_count--; @@ -251,7 +251,7 @@ void iwl_rx_allocate(struct iwl_priv *priv) rxb = list_entry(element, struct iwl_rx_mem_buffer, list); /* Alloc a new receive buffer */ - rxb->skb = alloc_skb(priv->hw_params.rx_buf_size, + rxb->skb = alloc_skb(priv->hw_params.rx_buf_size + 256, __GFP_NOWARN | GFP_ATOMIC); if (!rxb->skb) { if (net_ratelimit()) @@ -266,9 +266,17 @@ void iwl_rx_allocate(struct iwl_priv *priv) list_del(element); /* Get physical address of RB/SKB */ - rxb->dma_addr = - pci_map_single(priv->pci_dev, rxb->skb->data, - priv->hw_params.rx_buf_size, PCI_DMA_FROMDEVICE); + rxb->real_dma_addr = pci_map_single( + priv->pci_dev, + rxb->skb->data, + priv->hw_params.rx_buf_size + 256, + PCI_DMA_FROMDEVICE); + /* dma address must be no more than 36 bits */ + BUG_ON(rxb->real_dma_addr & ~DMA_BIT_MASK(36)); + /* and also 256 byte aligned! */ + rxb->aligned_dma_addr = ALIGN(rxb->real_dma_addr, 256); + skb_reserve(rxb->skb, rxb->aligned_dma_addr - rxb->real_dma_addr); + list_add_tail(&rxb->list, &rxq->rx_free); rxq->free_count++; } @@ -300,8 +308,8 @@ void iwl_rx_queue_free(struct iwl_priv *priv, struct iwl_rx_queue *rxq) for (i = 0; i < RX_QUEUE_SIZE + RX_FREE_BUFFERS; i++) { if (rxq->pool[i].skb != NULL) { pci_unmap_single(priv->pci_dev, - rxq->pool[i].dma_addr, - priv->hw_params.rx_buf_size, + rxq->pool[i].real_dma_addr, + priv->hw_params.rx_buf_size + 256, PCI_DMA_FROMDEVICE); dev_kfree_skb(rxq->pool[i].skb); } @@ -354,8 +362,8 @@ void iwl_rx_queue_reset(struct iwl_priv *priv, struct iwl_rx_queue *rxq) * to an SKB, so we need to unmap and free potential storage */ if (rxq->pool[i].skb != NULL) { pci_unmap_single(priv->pci_dev, - rxq->pool[i].dma_addr, - priv->hw_params.rx_buf_size, + rxq->pool[i].real_dma_addr, + priv->hw_params.rx_buf_size + 256, PCI_DMA_FROMDEVICE); priv->alloc_rxb_skb--; dev_kfree_skb(rxq->pool[i].skb); |