linux-kernel - [ 50/83] iwlwifi: handle DMA mapping failures

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Date:	Wed, 21 Nov 2012 16:42:12 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk, Shuah Khan <shuah.khan@...com>,
	Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
	Johannes Berg <johannes.berg@...el.com>
Subject: [ 50/83] iwlwifi: handle DMA mapping failures

3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@...el.com>

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@...com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@...el.com>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/iwlwifi/pcie/rx.c |   23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

--- a/drivers/net/wireless/iwlwifi/pcie/rx.c
+++ b/drivers/net/wireless/iwlwifi/pcie/rx.c
@@ -314,6 +314,14 @@ static void iwlagn_rx_allocate(struct iw
 			dma_map_page(trans->dev, page, 0,
 				     PAGE_SIZE << trans_pcie->rx_page_order,
 				     DMA_FROM_DEVICE);
+		if (dma_mapping_error(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, trans_pcie->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! */
@@ -463,8 +471,19 @@ static void iwl_rx_handle_rxbuf(struct i
 			dma_map_page(trans->dev, rxb->page, 0,
 				     PAGE_SIZE << trans_pcie->rx_page_order,
 				     DMA_FROM_DEVICE);
-		list_add_tail(&rxb->list, &rxq->rx_free);
-		rxq->free_count++;
+		if (dma_mapping_error(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, trans_pcie->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);
 	spin_unlock_irqrestore(&rxq->lock, flags);


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