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
[EMAIL PROTECTED] wrote on 12/09/2005 12:04:06 AM:
> Quoting Michael S. Tsirkin <[EMAIL PROTECTED]>:
> > 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 <[EMAIL PROTECTED]>
>
> 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 <[EMAIL PROTECTED]>
>
> 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
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