If napi is enabled while cq is being drained, it creates a race on priv->ibwc
between ipoib_poll and ipoib_drain_cq, leading to memory corruption.
 The solution is to enable/disable napi in ipoib_ib_dev_open/stop instead of in
ipoib_open/stop, and sync napi on INITIALIZED bit instead on ADMIN_UP bit. This
way napi will be disabled when ipoib_drain_cq is called.

Signed-off-by: Yossi Etigin <[email protected]>

---
Fix bugzilla #1587.

Index: b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
===================================================================
--- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c   2009-04-09 13:48:27.000000000 
+0300
+++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c   2009-04-10 17:58:10.000000000 
+0300
@@ -685,7 +685,8 @@ int ipoib_ib_dev_open(struct net_device 
        queue_delayed_work(ipoib_workqueue, &priv->ah_reap_task,
                           round_jiffies_relative(HZ));
 
-       set_bit(IPOIB_FLAG_INITIALIZED, &priv->flags);
+       if (!test_and_set_bit(IPOIB_FLAG_INITIALIZED, &priv->flags))
+               napi_enable(&priv->napi);
 
        return 0;
 }
@@ -804,7 +805,8 @@ int ipoib_ib_dev_stop(struct net_device 
        struct ipoib_tx_buf *tx_req;
        int i;
 
-       clear_bit(IPOIB_FLAG_INITIALIZED, &priv->flags);
+       if (test_and_clear_bit(IPOIB_FLAG_INITIALIZED, &priv->flags))
+               napi_disable(&priv->napi);
 
        ipoib_cm_dev_stop(dev);
 
Index: b/drivers/infiniband/ulp/ipoib/ipoib_main.c
===================================================================
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c 2009-04-09 15:16:24.000000000 
+0300
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c 2009-04-10 18:26:11.000000000 
+0300
@@ -106,8 +106,7 @@ int ipoib_open(struct net_device *dev)
 
        ipoib_dbg(priv, "bringing up interface\n");
 
-       if (!test_and_set_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
-               napi_enable(&priv->napi);
+       set_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags);
 
        if (ipoib_pkey_dev_delay_open(dev))
                return 0;
@@ -143,7 +142,6 @@ err_stop:
        ipoib_ib_dev_stop(dev, 1);
 
 err_disable:
-       napi_disable(&priv->napi);
        clear_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags);
 
        return -EINVAL;
@@ -156,7 +154,6 @@ static int ipoib_stop(struct net_device 
        ipoib_dbg(priv, "stopping interface\n");
 
        clear_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags);
-       napi_disable(&priv->napi);
 
        netif_stop_queue(dev);
 
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