[openib-general] [PATCH fixed] was Re: [PATCH] ipoib_multicast/ipoib_mcast_send race

[Krishna Kumar2]

Hi Micheal,

Is there a reason to have the atomic set_bit() within a lock (even for 
a race condition of stop vs send, it doesn't seem to be required) ?
Which means the test_bit() can also be put before the existing lock...

Thanks,

- KK

openib-general-bounces at openib.org wrote on 12/09/2005 12:04:06 AM:

> Quoting Michael S. Tsirkin <mst at mellanox.co.il>:
> > Subject: [PATCH] ipoib_multicast/ipoib_mcast_send race
> > 
> > Hello, Roland!
> > Here's another race scenario.
> > 
> > ---
> > 
> > Fix the following race scenario:
> > device is up.
> > port event or set mcast list triggers ipoib_mcast_stop_thread, 
> > This cancels the query and waits on mcast "done" completion.
> > completion is called and "done" is set.
> > Meanwhile, ipoib_mcast_send arrives and starts a new query,
> > re-initializing "done".
> > 
> > Signed-off-by: Michael S. Tsirkin <mst at mellanox.co.il>
> 
> The patch I posted previously leaked an skb when a multicast
> send arrived while the mcast thread is stopped.
> 
> Further, there's an additional issue that I saw in testing:
> ipoib_mcast_send may get called when priv->broadcast is NULL
> (e.g. if the device was downed and then upped internally because
> of a port event).
> If this happends and the sendonly join request gets completed before
> priv->broadcast is set, we get an oops that I posted previously.
> 
> Here's a better patch to address these two problems.
> It has been running fine here for a while now.
> 
> Please note that this replaces the ipoib_multicast/ipoib_mcast_send 
patch,
> but not the ADMIN_UP patch that I posted previously.
> 
> ---
> 
> Do not send multicasts if mcast thread is stopped or if
> priv->broadcast is not set.
> 
> Signed-off-by: Michael S. Tsirkin <mst at mellanox.co.il>
> 
> Index: openib/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
> ===================================================================
> --- openib/drivers/infiniband/ulp/ipoib/ipoib_multicast.c   (revision 
4222)
> +++ openib/drivers/infiniband/ulp/ipoib/ipoib_multicast.c   (working 
copy)
> @@ -582,6 +582,10 @@ int ipoib_mcast_start_thread(struct net_
>        queue_work(ipoib_workqueue, &priv->mcast_task);
>     up(&mcast_mutex);
> 
> +   spin_lock_irq(&priv->lock);
> +   set_bit(IPOIB_MCAST_STARTED, &priv->flags);
> +   spin_unlock_irq(&priv->lock);
> +
>     return 0;
>  }
> 
> @@ -592,6 +596,10 @@ int ipoib_mcast_stop_thread(struct net_d
> 
>     ipoib_dbg_mcast(priv, "stopping multicast thread\n");
> 
> +   spin_lock_irq(&priv->lock);
> +   clear_bit(IPOIB_MCAST_STARTED, &priv->flags);
> +   spin_unlock_irq(&priv->lock);
> +
>     down(&mcast_mutex);
>     clear_bit(IPOIB_MCAST_RUN, &priv->flags);
>     cancel_delayed_work(&priv->mcast_task);
> @@ -674,6 +682,11 @@ void ipoib_mcast_send(struct net_device 
>      */
>     spin_lock(&priv->lock);
> 
> +   if (!test_bit(IPOIB_MCAST_STARTED, &priv->flags) || 
!priv->broadcast) {
> +      dev_kfree_skb_any(skb);
> +      goto unlock;
> +   }
> +
>     mcast = __ipoib_mcast_find(dev, mgid);
>     if (!mcast) {
>        /* Let's create a new send only group now */
> @@ -732,6 +745,7 @@ out:
>        ipoib_send(dev, skb, mcast->ah, IB_MULTICAST_QPN);
>     }
> 
> +unlock:
>     spin_unlock(&priv->lock);
>  }
> 
> Index: openib/drivers/infiniband/ulp/ipoib/ipoib.h
> ===================================================================
> --- openib/drivers/infiniband/ulp/ipoib/ipoib.h   (revision 4222)
> +++ openib/drivers/infiniband/ulp/ipoib/ipoib.h   (working copy)
> @@ -78,6 +78,7 @@ enum {
>     IPOIB_FLAG_SUBINTERFACE   = 4,
>     IPOIB_MCAST_RUN      = 5,
>     IPOIB_STOP_REAPER         = 6,
> +   IPOIB_MCAST_STARTED       = 7,
> 
>     IPOIB_MAX_BACKOFF_SECONDS = 16,
> 
> 
> -- 
> MST
> _______________________________________________
> openib-general mailing list
> openib-general at openib.org
> http://openib.org/mailman/listinfo/openib-general
> 
> To unsubscribe, please visit 
http://openib.org/mailman/listinfo/openib-general
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openfabrics.org/pipermail/general/attachments/20051209/588a4bca/attachment.html>