iwlwifi: handle DMA mapping failures

commit 7c34158231b2eda8dcbd297be2bb1559e69cb433 upstream.

The RX replenish code doesn't handle DMA mapping failures,
which will cause issues if there actually is a failure. This
was reported by Shuah Khan who found a DMA mapping framework
warning ("device driver failed to check map error").

Reported-by: Shuah Khan <shuah.khan@hp.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
[bwh: Backported to 3.2:
 - Adjust filename, context, indentation
 - Use bus(trans) instead of trans where necessary
 - Use hw_params(trans).rx_page_order instead of trans_pcie->rx_page_order]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c
index d580da2..9fefb56 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c
@@ -311,6 +311,14 @@ static void iwlagn_rx_allocate(struct iwl_trans *trans, gfp_t priority)
                rxb->page_dma = dma_map_page(bus(trans)->dev, page, 0,
                                PAGE_SIZE << hw_params(trans).rx_page_order,
                                DMA_FROM_DEVICE);
+               if (dma_mapping_error(bus(trans)->dev, rxb->page_dma)) {
+                       rxb->page = NULL;
+                       spin_lock_irqsave(&rxq->lock, flags);
+                       list_add(&rxb->list, &rxq->rx_used);
+                       spin_unlock_irqrestore(&rxq->lock, flags);
+                       __free_pages(page, hw_params(trans).rx_page_order);
+                       return;
+               }
                /* dma address must be no more than 36 bits */
                BUG_ON(rxb->page_dma & ~DMA_BIT_MASK(36));
                /* and also 256 byte aligned! */
@@ -489,8 +497,19 @@ static void iwl_rx_handle(struct iwl_trans *trans)
                                0, PAGE_SIZE <<
                                    hw_params(trans).rx_page_order,
                                DMA_FROM_DEVICE);
-                       list_add_tail(&rxb->list, &rxq->rx_free);
-                       rxq->free_count++;
+                       if (dma_mapping_error(bus(trans)->dev, rxb->page_dma)) {
+                               /*
+                                * free the page(s) as well to not break
+                                * the invariant that the items on the used
+                                * list have no page(s)
+                                */
+                               __free_pages(rxb->page, hw_params(trans).rx_page_order);
+                               rxb->page = NULL;
+                               list_add_tail(&rxb->list, &rxq->rx_used);
+                       } else {
+                               list_add_tail(&rxb->list, &rxq->rx_free);
+                               rxq->free_count++;
+                       }
                } else
                        list_add_tail(&rxb->list, &rxq->rx_used);