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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 17:30:02 +00:00
IB/ipoib: drop mcast_mutex usage
We needed the mcast_mutex when we had to prevent the join completion callback from having the value it stored in mcast->mc overwritten by a delayed return from ib_sa_join_multicast. By storing the return of ib_sa_join_multicast in an intermediate variable, we prevent a delayed return from ib_sa_join_multicast overwriting the valid contents of mcast->mc, and we no longer need a mutex to force the join callback to run after the return of ib_sa_join_multicast. This allows us to do away with the mutex entirely and protect our critical sections with a just a spinlock instead. This is highly desirable as there were some places where we couldn't use a mutex because the code was not allowed to sleep, and so we were currently using a mix of mutex and spinlock to protect what we needed to protect. Now we only have a spin lock and the locking complexity is greatly reduced. Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
parent
d2fe937ce6
commit
1c0453d64a
1 changed files with 32 additions and 38 deletions
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@ -55,8 +55,6 @@ MODULE_PARM_DESC(mcast_debug_level,
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"Enable multicast debug tracing if > 0");
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#endif
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static DEFINE_MUTEX(mcast_mutex);
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struct ipoib_mcast_iter {
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struct net_device *dev;
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union ib_gid mgid;
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@ -67,7 +65,7 @@ struct ipoib_mcast_iter {
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};
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/*
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* This should be called with the mcast_mutex held
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* This should be called with the priv->lock held
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*/
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static void __ipoib_mcast_schedule_join_thread(struct ipoib_dev_priv *priv,
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struct ipoib_mcast *mcast,
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@ -352,16 +350,6 @@ static int ipoib_mcast_join_complete(int status,
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"sendonly " : "",
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mcast->mcmember.mgid.raw, status);
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/*
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* We have to take the mutex to force mcast_join to
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* return from ib_sa_multicast_join and set mcast->mc to a
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* valid value. Otherwise we were racing with ourselves in
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* that we might fail here, but get a valid return from
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* ib_sa_multicast_join after we had cleared mcast->mc here,
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* resulting in mis-matched joins and leaves and a deadlock
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*/
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mutex_lock(&mcast_mutex);
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/* We trap for port events ourselves. */
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if (status == -ENETRESET) {
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status = 0;
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@ -383,8 +371,10 @@ static int ipoib_mcast_join_complete(int status,
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* send out all of the non-broadcast joins
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*/
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if (mcast == priv->broadcast) {
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spin_lock_irq(&priv->lock);
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queue_work(priv->wq, &priv->carrier_on_task);
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__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
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goto out_locked;
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}
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} else {
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if (mcast->logcount++ < 20) {
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@ -417,16 +407,28 @@ static int ipoib_mcast_join_complete(int status,
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dev_kfree_skb_any(skb_dequeue(&mcast->pkt_queue));
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}
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netif_tx_unlock_bh(dev);
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} else
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} else {
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spin_lock_irq(&priv->lock);
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/* Requeue this join task with a backoff delay */
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__ipoib_mcast_schedule_join_thread(priv, mcast, 1);
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goto out_locked;
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}
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}
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out:
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clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
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spin_lock_irq(&priv->lock);
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out_locked:
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/*
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* Make sure to set mcast->mc before we clear the busy flag to avoid
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* racing with code that checks for BUSY before checking mcast->mc
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*/
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if (status)
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mcast->mc = NULL;
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else
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mcast->mc = multicast;
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clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
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spin_unlock_irq(&priv->lock);
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complete(&mcast->done);
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mutex_unlock(&mcast_mutex);
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return status;
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}
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@ -434,6 +436,7 @@ static void ipoib_mcast_join(struct net_device *dev, struct ipoib_mcast *mcast,
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int create)
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{
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struct ipoib_dev_priv *priv = netdev_priv(dev);
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struct ib_sa_multicast *multicast;
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struct ib_sa_mcmember_rec rec = {
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.join_state = 1
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};
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@ -475,18 +478,19 @@ static void ipoib_mcast_join(struct net_device *dev, struct ipoib_mcast *mcast,
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rec.hop_limit = priv->broadcast->mcmember.hop_limit;
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}
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mutex_lock(&mcast_mutex);
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mcast->mc = ib_sa_join_multicast(&ipoib_sa_client, priv->ca, priv->port,
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multicast = ib_sa_join_multicast(&ipoib_sa_client, priv->ca, priv->port,
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&rec, comp_mask, GFP_KERNEL,
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ipoib_mcast_join_complete, mcast);
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if (IS_ERR(mcast->mc)) {
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clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
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ret = PTR_ERR(mcast->mc);
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if (IS_ERR(multicast)) {
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ret = PTR_ERR(multicast);
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ipoib_warn(priv, "ib_sa_join_multicast failed, status %d\n", ret);
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spin_lock_irq(&priv->lock);
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/* Requeue this join task with a backoff delay */
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__ipoib_mcast_schedule_join_thread(priv, mcast, 1);
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clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
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spin_unlock_irq(&priv->lock);
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complete(&mcast->done);
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}
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mutex_unlock(&mcast_mutex);
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}
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void ipoib_mcast_join_task(struct work_struct *work)
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@ -515,15 +519,6 @@ void ipoib_mcast_join_task(struct work_struct *work)
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else
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memcpy(priv->dev->dev_addr + 4, priv->local_gid.raw, sizeof (union ib_gid));
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/*
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* We have to hold the mutex to keep from racing with the join
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* completion threads on setting flags on mcasts, and we have
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* to hold the priv->lock because dev_flush will remove entries
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* out from underneath us, so at a minimum we need the lock
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* through the time that we do the for_each loop of the mcast
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* list or else dev_flush can make us oops.
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*/
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mutex_lock(&mcast_mutex);
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spin_lock_irq(&priv->lock);
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if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
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goto out;
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@ -584,9 +579,7 @@ void ipoib_mcast_join_task(struct work_struct *work)
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else
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create = 1;
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spin_unlock_irq(&priv->lock);
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mutex_unlock(&mcast_mutex);
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ipoib_mcast_join(dev, mcast, create);
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mutex_lock(&mcast_mutex);
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spin_lock_irq(&priv->lock);
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} else if (!delay_until ||
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time_before(mcast->delay_until, delay_until))
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@ -608,7 +601,6 @@ void ipoib_mcast_join_task(struct work_struct *work)
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set_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
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}
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spin_unlock_irq(&priv->lock);
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mutex_unlock(&mcast_mutex);
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if (mcast)
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ipoib_mcast_join(dev, mcast, create);
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}
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@ -616,13 +608,14 @@ void ipoib_mcast_join_task(struct work_struct *work)
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int ipoib_mcast_start_thread(struct net_device *dev)
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{
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struct ipoib_dev_priv *priv = netdev_priv(dev);
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unsigned long flags;
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ipoib_dbg_mcast(priv, "starting multicast thread\n");
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mutex_lock(&mcast_mutex);
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spin_lock_irqsave(&priv->lock, flags);
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set_bit(IPOIB_MCAST_RUN, &priv->flags);
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__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
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mutex_unlock(&mcast_mutex);
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spin_unlock_irqrestore(&priv->lock, flags);
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return 0;
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}
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@ -630,13 +623,14 @@ int ipoib_mcast_start_thread(struct net_device *dev)
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int ipoib_mcast_stop_thread(struct net_device *dev)
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{
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struct ipoib_dev_priv *priv = netdev_priv(dev);
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unsigned long flags;
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ipoib_dbg_mcast(priv, "stopping multicast thread\n");
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mutex_lock(&mcast_mutex);
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spin_lock_irqsave(&priv->lock, flags);
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clear_bit(IPOIB_MCAST_RUN, &priv->flags);
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cancel_delayed_work(&priv->mcast_task);
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mutex_unlock(&mcast_mutex);
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spin_unlock_irqrestore(&priv->lock, flags);
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flush_workqueue(priv->wq);
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