From: Yossi Etigin Date: Tue, 16 Sep 2008 18:57:45 +0000 (-0700) Subject: IPoIB: Fix deadlock on RTNL between bcast join comp and ipoib_stop() X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e8224e4b804b4fd26723191c1891101a5959bb8a;p=linux-2.6 IPoIB: Fix deadlock on RTNL between bcast join comp and ipoib_stop() Taking rtnl_lock in ipoib_mcast_join_complete() causes a deadlock with ipoib_stop(). We avoid it by scheduling the piece of code that takes the lock on ipoib_workqueue instead of executing it directly. This works because we only flush the ipoib_workqueue with the RTNL not held. The deadlock happens because ipoib_stop() calls ipoib_ib_dev_down() which calls ipoib_mcast_dev_flush(), which calls ipoib_mcast_free(), which calls ipoib_mcast_leave(). The latter calls ib_sa_free_multicast(), and this waits until the multicast completion handler finishes. This handler is ipoib_mcast_join_complete(), which waits for the rtnl_lock(), which was already taken by ipoib_stop(). This bug was introduced in commit a77a57a1 ("IPoIB: Fix deadlock on RTNL in ipoib_stop()"). Signed-off-by: Yossi Etigin Signed-off-by: Roland Dreier --- diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h index b0ffc9abe8..05eb41b8ab 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib.h +++ b/drivers/infiniband/ulp/ipoib/ipoib.h @@ -293,6 +293,7 @@ struct ipoib_dev_priv { struct delayed_work pkey_poll_task; struct delayed_work mcast_task; + struct work_struct carrier_on_task; struct work_struct flush_light; struct work_struct flush_normal; struct work_struct flush_heavy; @@ -464,6 +465,7 @@ int ipoib_dev_init(struct net_device *dev, struct ib_device *ca, int port); void ipoib_dev_cleanup(struct net_device *dev); void ipoib_mcast_join_task(struct work_struct *work); +void ipoib_mcast_carrier_on_task(struct work_struct *work); void ipoib_mcast_send(struct net_device *dev, void *mgid, struct sk_buff *skb); void ipoib_mcast_restart_task(struct work_struct *work); diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c index 7e9e218738..1b1df5cc41 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_main.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c @@ -1075,6 +1075,7 @@ static void ipoib_setup(struct net_device *dev) INIT_DELAYED_WORK(&priv->pkey_poll_task, ipoib_pkey_poll); INIT_DELAYED_WORK(&priv->mcast_task, ipoib_mcast_join_task); + INIT_WORK(&priv->carrier_on_task, ipoib_mcast_carrier_on_task); INIT_WORK(&priv->flush_light, ipoib_ib_dev_flush_light); INIT_WORK(&priv->flush_normal, ipoib_ib_dev_flush_normal); INIT_WORK(&priv->flush_heavy, ipoib_ib_dev_flush_heavy); diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c index ac33c8f3ea..aae28620a6 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c @@ -366,6 +366,21 @@ static int ipoib_mcast_sendonly_join(struct ipoib_mcast *mcast) return ret; } +void ipoib_mcast_carrier_on_task(struct work_struct *work) +{ + struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv, + carrier_on_task); + + /* + * Take rtnl_lock to avoid racing with ipoib_stop() and + * turning the carrier back on while a device is being + * removed. + */ + rtnl_lock(); + netif_carrier_on(priv->dev); + rtnl_unlock(); +} + static int ipoib_mcast_join_complete(int status, struct ib_sa_multicast *multicast) { @@ -392,16 +407,12 @@ static int ipoib_mcast_join_complete(int status, &priv->mcast_task, 0); mutex_unlock(&mcast_mutex); - if (mcast == priv->broadcast) { - /* - * Take RTNL lock here to avoid racing with - * ipoib_stop() and turning the carrier back - * on while a device is being removed. - */ - rtnl_lock(); - netif_carrier_on(dev); - rtnl_unlock(); - } + /* + * Defer carrier on work to ipoib_workqueue to avoid a + * deadlock on rtnl_lock here. + */ + if (mcast == priv->broadcast) + queue_work(ipoib_workqueue, &priv->carrier_on_task); return 0; }