Revert "IPoIB: fix MCAST_FLAG_BUSY usage"

This reverts commit 016d9fb25cd9817ea9c723f4f7ecd978636b4489.

The series of IPoIB bug fixes that went into 3.19-rc1 introduce
regressions, and after trying to sort things out, we decided to revert
to 3.18's IPoIB driver and get things right for 3.20.

Signed-off-by: Roland Dreier <roland@purestorage.com>

2 files changed, 57 insertions, 101 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index f4c1b20b23b2..d7562beb5423 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -98,15 +98,9 @@ enum {
 
         IPOIB_MCAST_FLAG_FOUND    = 0,  /* used in set_multicast_list */
         IPOIB_MCAST_FLAG_SENDONLY = 1,
-        /*
-         * For IPOIB_MCAST_FLAG_BUSY
-         * When set, in flight join and mcast->mc is unreliable
-         * When clear and mcast->mc IS_ERR_OR_NULL, need to restart or
-         *   haven't started yet
-         * When clear and mcast->mc is valid pointer, join was successful
-         */
-        IPOIB_MCAST_FLAG_BUSY     = 2,
+        IPOIB_MCAST_FLAG_BUSY     = 2,  /* joining or already joined */
         IPOIB_MCAST_FLAG_ATTACHED = 3,
+        IPOIB_MCAST_JOIN_STARTED  = 4,
 
         MAX_SEND_CQE              = 16,
         IPOIB_CM_COPYBREAK        = 256,
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index a52c9f3f7e42..9862c76a83f7 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -271,27 +271,16 @@ ipoib_mcast_sendonly_join_complete(int status,
         struct ipoib_mcast *mcast = multicast->context;
         struct net_device *dev = mcast->dev;
 
-        /*
-         * We have to take the mutex to force mcast_sendonly_join to
-         * return from ib_sa_multicast_join and set mcast->mc to a
-         * valid value.  Otherwise we were racing with ourselves in
-         * that we might fail here, but get a valid return from
-         * ib_sa_multicast_join after we had cleared mcast->mc here,
-         * resulting in mis-matched joins and leaves and a deadlock
-         */
-        mutex_lock(&mcast_mutex);
-
         /* We trap for port events ourselves. */
         if (status == -ENETRESET)
-                goto out;
+                return 0;
 
         if (!status)
                 status = ipoib_mcast_join_finish(mcast, &multicast->rec);
 
         if (status) {
                 if (mcast->logcount++ < 20)
-                        ipoib_dbg_mcast(netdev_priv(dev), "sendonly multicast "
-                                        "join failed for %pI6, status %d\n",
+                        ipoib_dbg_mcast(netdev_priv(dev), "multicast join failed for %pI6, status %d\n",
                                         mcast->mcmember.mgid.raw, status);
 
                 /* Flush out any queued packets */
@@ -301,15 +290,11 @@ ipoib_mcast_sendonly_join_complete(int status,
                         dev_kfree_skb_any(skb_dequeue(&mcast->pkt_queue));
                 }
                 netif_tx_unlock_bh(dev);
+
+                /* Clear the busy flag so we try again */
+                status = test_and_clear_bit(IPOIB_MCAST_FLAG_BUSY,
+                                            &mcast->flags);
         }
-out:
-        clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
-        if (status)
-                mcast->mc = NULL;
-        complete(&mcast->done);
-        if (status == -ENETRESET)
-                status = 0;
-        mutex_unlock(&mcast_mutex);
         return status;
 }
 
@@ -327,14 +312,12 @@ static int ipoib_mcast_sendonly_join(struct ipoib_mcast *mcast)
         int ret = 0;
 
         if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags)) {
-                ipoib_dbg_mcast(priv, "device shutting down, no sendonly "
-                                "multicast joins\n");
+                ipoib_dbg_mcast(priv, "device shutting down, no multicast joins\n");
                 return -ENODEV;
         }
 
-        if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags)) {
-                ipoib_dbg_mcast(priv, "multicast entry busy, skipping "
-                                "sendonly join\n");
+        if (test_and_set_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags)) {
+                ipoib_dbg_mcast(priv, "multicast entry busy, skipping\n");
                 return -EBUSY;
         }
 
@@ -342,9 +325,6 @@ static int ipoib_mcast_sendonly_join(struct ipoib_mcast *mcast)
         rec.port_gid = priv->local_gid;
         rec.pkey     = cpu_to_be16(priv->pkey);
 
-        mutex_lock(&mcast_mutex);
-        init_completion(&mcast->done);
-        set_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
         mcast->mc = ib_sa_join_multicast(&ipoib_sa_client, priv->ca,
                                          priv->port, &rec,
                                          IB_SA_MCMEMBER_REC_MGID        |
@@ -357,14 +337,12 @@ static int ipoib_mcast_sendonly_join(struct ipoib_mcast *mcast)
         if (IS_ERR(mcast->mc)) {
                 ret = PTR_ERR(mcast->mc);
                 clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
-                complete(&mcast->done);
-                ipoib_warn(priv, "ib_sa_join_multicast for sendonly join "
-                           "failed (ret = %d)\n", ret);
+                ipoib_warn(priv, "ib_sa_join_multicast failed (ret = %d)\n",
+                           ret);
         } else {
-                ipoib_dbg_mcast(priv, "no multicast record for %pI6, starting "
-                                "sendonly join\n", mcast->mcmember.mgid.raw);
+                ipoib_dbg_mcast(priv, "no multicast record for %pI6, starting join\n",
+                                mcast->mcmember.mgid.raw);
         }
-        mutex_unlock(&mcast_mutex);
 
         return ret;
 }
@@ -412,28 +390,22 @@ static int ipoib_mcast_join_complete(int status,
         ipoib_dbg_mcast(priv, "join completion for %pI6 (status %d)\n",
                         mcast->mcmember.mgid.raw, status);
 
-        /*
-         * We have to take the mutex to force mcast_join to
-         * return from ib_sa_multicast_join and set mcast->mc to a
-         * valid value.  Otherwise we were racing with ourselves in
-         * that we might fail here, but get a valid return from
-         * ib_sa_multicast_join after we had cleared mcast->mc here,
-         * resulting in mis-matched joins and leaves and a deadlock
-         */
-        mutex_lock(&mcast_mutex);
-
         /* We trap for port events ourselves. */
-        if (status == -ENETRESET)
+        if (status == -ENETRESET) {
+                status = 0;
                 goto out;
+        }
 
         if (!status)
                 status = ipoib_mcast_join_finish(mcast, &multicast->rec);
 
         if (!status) {
                 mcast->backoff = 1;
+                mutex_lock(&mcast_mutex);
                 if (test_bit(IPOIB_MCAST_RUN, &priv->flags))
                         queue_delayed_work(ipoib_workqueue,
                                            &priv->mcast_task, 0);
+                mutex_unlock(&mcast_mutex);
 
                 /*
                  * Defer carrier on work to ipoib_workqueue to avoid a
@@ -441,35 +413,37 @@ static int ipoib_mcast_join_complete(int status,
                  */
                 if (mcast == priv->broadcast)
                         queue_work(ipoib_workqueue, &priv->carrier_on_task);
-        } else {
-                if (mcast->logcount++ < 20) {
-                        if (status == -ETIMEDOUT || status == -EAGAIN) {
-                                ipoib_dbg_mcast(priv, "multicast join failed for %pI6, status %d\n",
-                                                mcast->mcmember.mgid.raw, status);
-                        } else {
-                                ipoib_warn(priv, "multicast join failed for %pI6, status %d\n",
-                                           mcast->mcmember.mgid.raw, status);
-                        }
-                }
 
-                mcast->backoff *= 2;
-                if (mcast->backoff > IPOIB_MAX_BACKOFF_SECONDS)
-                        mcast->backoff = IPOIB_MAX_BACKOFF_SECONDS;
+                status = 0;
+                goto out;
         }
-out:
+
+        if (mcast->logcount++ < 20) {
+                if (status == -ETIMEDOUT || status == -EAGAIN) {
+                        ipoib_dbg_mcast(priv, "multicast join failed for %pI6, status %d\n",
+                                        mcast->mcmember.mgid.raw, status);
+                } else {
+                        ipoib_warn(priv, "multicast join failed for %pI6, status %d\n",
+                                   mcast->mcmember.mgid.raw, status);
+                }
+        }
+
+        mcast->backoff *= 2;
+        if (mcast->backoff > IPOIB_MAX_BACKOFF_SECONDS)
+                mcast->backoff = IPOIB_MAX_BACKOFF_SECONDS;
+
+        /* Clear the busy flag so we try again */
+        status = test_and_clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
+
+        mutex_lock(&mcast_mutex);
         spin_lock_irq(&priv->lock);
-        clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
-        if (status)
-                mcast->mc = NULL;
-        complete(&mcast->done);
-        if (status == -ENETRESET)
-                status = 0;
-        if (status && test_bit(IPOIB_MCAST_RUN, &priv->flags))
+        if (test_bit(IPOIB_MCAST_RUN, &priv->flags))
                 queue_delayed_work(ipoib_workqueue, &priv->mcast_task,
                                    mcast->backoff * HZ);
         spin_unlock_irq(&priv->lock);
         mutex_unlock(&mcast_mutex);
-
+out:
+        complete(&mcast->done);
         return status;
 }
 
@@ -518,9 +492,10 @@ static void ipoib_mcast_join(struct net_device *dev, struct ipoib_mcast *mcast,
                 rec.hop_limit     = priv->broadcast->mcmember.hop_limit;
         }
 
-        mutex_lock(&mcast_mutex);
-        init_completion(&mcast->done);
         set_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
+        init_completion(&mcast->done);
+        set_bit(IPOIB_MCAST_JOIN_STARTED, &mcast->flags);
+
         mcast->mc = ib_sa_join_multicast(&ipoib_sa_client, priv->ca, priv->port,
                                          &rec, comp_mask, GFP_KERNEL,
                                          ipoib_mcast_join_complete, mcast);
@@ -534,12 +509,13 @@ static void ipoib_mcast_join(struct net_device *dev, struct ipoib_mcast *mcast,
                 if (mcast->backoff > IPOIB_MAX_BACKOFF_SECONDS)
                         mcast->backoff = IPOIB_MAX_BACKOFF_SECONDS;
 
+                mutex_lock(&mcast_mutex);
                 if (test_bit(IPOIB_MCAST_RUN, &priv->flags))
                         queue_delayed_work(ipoib_workqueue,
                                            &priv->mcast_task,
                                            mcast->backoff * HZ);
+                mutex_unlock(&mcast_mutex);
         }
-        mutex_unlock(&mcast_mutex);
 }
 
 void ipoib_mcast_join_task(struct work_struct *work)
@@ -592,8 +568,7 @@ void ipoib_mcast_join_task(struct work_struct *work)
         }
 
         if (!test_bit(IPOIB_MCAST_FLAG_ATTACHED, &priv->broadcast->flags)) {
-                if (IS_ERR_OR_NULL(priv->broadcast->mc) &&
-                    !test_bit(IPOIB_MCAST_FLAG_BUSY, &priv->broadcast->flags))
+                if (!test_bit(IPOIB_MCAST_FLAG_BUSY, &priv->broadcast->flags))
                         ipoib_mcast_join(dev, priv->broadcast, 0);
                 return;
         }
@@ -601,33 +576,23 @@ void ipoib_mcast_join_task(struct work_struct *work)
         while (1) {
                 struct ipoib_mcast *mcast = NULL;
 
-                /*
-                 * Need the mutex so our flags are consistent, need the
-                 * priv->lock so we don't race with list removals in either
-                 * mcast_dev_flush or mcast_restart_task
-                 */
-                mutex_lock(&mcast_mutex);
                 spin_lock_irq(&priv->lock);
                 list_for_each_entry(mcast, &priv->multicast_list, list) {
-                        if (IS_ERR_OR_NULL(mcast->mc) &&
-                            !test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags) &&
-                            !test_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags)) {
+                        if (!test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags)
+                            && !test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags)
+                            && !test_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags)) {
                                 /* Found the next unjoined group */
                                 break;
                         }
                 }
                 spin_unlock_irq(&priv->lock);
-                mutex_unlock(&mcast_mutex);
 
                 if (&mcast->list == &priv->multicast_list) {
                         /* All done */
                         break;
                 }
 
-                if (test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags))
-                        ipoib_mcast_sendonly_join(mcast);
-                else
-                        ipoib_mcast_join(dev, mcast, 1);
+                ipoib_mcast_join(dev, mcast, 1);
                 return;
         }
 
@@ -673,9 +638,6 @@ static int ipoib_mcast_leave(struct net_device *dev, struct ipoib_mcast *mcast)
         int ret = 0;
 
         if (test_and_clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
-                ipoib_warn(priv, "ipoib_mcast_leave on an in-flight join\n");
-
-        if (!IS_ERR_OR_NULL(mcast->mc))
                 ib_sa_free_multicast(mcast->mc);
 
         if (test_and_clear_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags)) {
@@ -728,8 +690,6 @@ void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb)
                 memcpy(mcast->mcmember.mgid.raw, mgid, sizeof (union ib_gid));
                 __ipoib_mcast_add(dev, mcast);
                 list_add_tail(&mcast->list, &priv->multicast_list);
-                if (!test_and_set_bit(IPOIB_MCAST_RUN, &priv->flags))
-                        queue_delayed_work(ipoib_workqueue, &priv->mcast_task, 0);
         }
 
         if (!mcast->ah) {
@@ -743,6 +703,8 @@ void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb)
                 if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
                         ipoib_dbg_mcast(priv, "no address vector, "
                                         "but multicast join already started\n");
+                else if (test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags))
+                        ipoib_mcast_sendonly_join(mcast);
 
                 /*
                  * If lookup completes between here and out:, don't
@@ -804,7 +766,7 @@ void ipoib_mcast_dev_flush(struct net_device *dev)
 
         /* seperate between the wait to the leave*/
         list_for_each_entry_safe(mcast, tmcast, &remove_list, list)
-                if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
+                if (test_bit(IPOIB_MCAST_JOIN_STARTED, &mcast->flags))
                         wait_for_completion(&mcast->done);
 
         list_for_each_entry_safe(mcast, tmcast, &remove_list, list) {