netdev - [PATCH] ibmveth: Fix endian issues with rx_no

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Message-ID: <20140822113652.7e4bdc78@kryten>
Date:	Fri, 22 Aug 2014 11:36:52 +1000
From:	Anton Blanchard <anton@...ba.org>
To:	santil@...ux.vnet.ibm.com, paulus@...ba.org
Cc:	linuxppc-dev@...ts.ozlabs.org, netdev@...r.kernel.org
Subject: [PATCH] ibmveth: Fix endian issues with rx_no_buffer statistic

Hidden away in the last 8 bytes of the buffer_list page is a solitary
statistic. It needs to be byte swapped or else ethtool -S will
produce numbers that terrify the user.

Since we do this in multiple places, create a helper function with a
comment explaining what is going on.

Signed-off-by: Anton Blanchard <anton@...ba.org>
Cc: stable@...r.kernel.org
---

Index: b/drivers/net/ethernet/ibm/ibmveth.c
===================================================================
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -292,6 +292,18 @@ failure:
 	atomic_add(buffers_added, &(pool->available));
 }
 
+/*
+ * The final 8 bytes of the buffer list is a counter of frames dropped
+ * because there was not a buffer in the buffer list capable of holding
+ * the frame.
+ */
+static void ibmveth_update_rx_no_buffer(struct ibmveth_adapter *adapter)
+{
+	__be64 *p = adapter->buffer_list_addr + 4096 - 8;
+
+	adapter->rx_no_buffer = be64_to_cpup(p);
+}
+
 /* replenish routine */
 static void ibmveth_replenish_task(struct ibmveth_adapter *adapter)
 {
@@ -307,8 +319,7 @@ static void ibmveth_replenish_task(struc
 			ibmveth_replenish_buffer_pool(adapter, pool);
 	}
 
-	adapter->rx_no_buffer = *(u64 *)(((char*)adapter->buffer_list_addr) +
-						4096 - 8);
+	ibmveth_update_rx_no_buffer(adapter);
 }
 
 /* empty and free ana buffer pool - also used to do cleanup in error paths */
@@ -698,8 +709,7 @@ static int ibmveth_close(struct net_devi
 
 	free_irq(netdev->irq, netdev);
 
-	adapter->rx_no_buffer = *(u64 *)(((char *)adapter->buffer_list_addr) +
-						4096 - 8);
+	ibmveth_update_rx_no_buffer(adapter);
 
 	ibmveth_cleanup(adapter);
 
--
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