sfc: Wait at most 10ms for the MC to finish reading out MAC statistics

[pandora-kernel.git] / drivers / net / sfc / siena.c

diff --git a/drivers/net/sfc/siena.c b/drivers/net/sfc/siena.c
index 1619fb5..e0c46f5 100644 (file)
--- a/drivers/net/sfc/siena.c
+++ b/drivers/net/sfc/siena.c
@@ -12,6 +12,7 @@
 #include <linux/delay.h>
 #include <linux/pci.h>
 #include <linux/module.h>
+#include <linux/slab.h>
 #include "net_driver.h"
 #include "bitfield.h"
 #include "efx.h"
@@ -455,8 +456,17 @@ static int siena_try_update_nic_stats(struct efx_nic *efx)
 
 static void siena_update_nic_stats(struct efx_nic *efx)
 {
-       while (siena_try_update_nic_stats(efx) == -EAGAIN)
-               cpu_relax();
+       int retry;
+
+       /* If we're unlucky enough to read statistics wduring the DMA, wait
+        * up to 10ms for it to finish (typically takes <500us) */
+       for (retry = 0; retry < 100; ++retry) {
+               if (siena_try_update_nic_stats(efx) == 0)
+                       return;
+               udelay(100);
+       }
+
+       /* Use the old values instead */
 }
 
 static void siena_start_nic_stats(struct efx_nic *efx)