[PATCH rdma-rc 0/2] RDMA fixes 2017-12-31

[PATCH rdma-rc 0/2] RDMA fixes 2017-12-31

[Leon Romanovsky]

Hi,

There are two small fixes, one fix to mlx4_ib_alloc_mr error flow, very
similar to commit 45e6ae7ef21b ("IB/mlx5: Fix mlx5_ib_alloc_mr error
flow") and another fix to race condition in IPoIB revealed by Enhanced
IPoIB tests.

Thanks

The patches are available in the git repository at:
  git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git tags/rdma-rc-2017-12-31

	Thanks
---------------------------------------

Erez Shitrit (1):
  IB/ipoib: Fix race condition in neigh creation

Leon Romanovsky (1):
  IB/mlx4: Fix mlx4_ib_alloc_mr error flow

 drivers/infiniband/hw/mlx4/mr.c                |  2 +-
 drivers/infiniband/ulp/ipoib/ipoib_main.c      | 25 ++++++++++++++++++-------
 drivers/infiniband/ulp/ipoib/ipoib_multicast.c |  5 ++++-
 3 files changed, 23 insertions(+), 9 deletions(-)

--
2.15.1

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[PATCH rdma-rc 1/2] IB/mlx4: Fix mlx4_ib_alloc_mr error flow

[Leon Romanovsky]

From: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

ibmr.device is being set only after ib_alloc_mr() is successfully complete.
Therefore, in case imlx4_mr_enable() returns with error, the error flow
unwinder calls to mlx4_free_priv_pages(), which uses ibmr.device.

Such usage causes to NULL dereference oops and to fix it, the IB device
should be set in the mr struct earlier stage (e.g. prior to calling
mlx4_free_priv_pages()).

Fixes: 1b2cd0fc673c ("IB/mlx4: Support the new memory registration API")
Signed-off-by: Nitzan Carmi <nitzanc-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
---
 drivers/infiniband/hw/mlx4/mr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx4/mr.c b/drivers/infiniband/hw/mlx4/mr.c
index 313bfb9ccb71..4975f3e6596e 100644
--- a/drivers/infiniband/hw/mlx4/mr.c
+++ b/drivers/infiniband/hw/mlx4/mr.c
@@ -642,7 +642,6 @@ struct ib_mr *mlx4_ib_alloc_mr(struct ib_pd *pd,
 		goto err_free_mr;

 	mr->max_pages = max_num_sg;
-
 	err = mlx4_mr_enable(dev->dev, &mr->mmr);
 	if (err)
 		goto err_free_pl;
@@ -653,6 +652,7 @@ struct ib_mr *mlx4_ib_alloc_mr(struct ib_pd *pd,
 	return &mr->ibmr;

 err_free_pl:
+	mr->ibmr.device = pd->device;
 	mlx4_free_priv_pages(mr);
 err_free_mr:
 	(void) mlx4_mr_free(dev->dev, &mr->mmr);
--
2.15.1

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[PATCH rdma-rc 2/2] IB/ipoib: Fix race condition in neigh creation

[Leon Romanovsky]

From: Erez Shitrit <erezsh-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

When using enhanced mode for IPoIB, two threads may execute xmit in
parallel to two different TX queues while the target is the same.
In this case, both of them will add the same neighbor to the path's
neigh link list and we might see the following message:

  list_add double add: new=ffff88024767a348, prev=ffff88024767a348...
  WARNING: lib/list_debug.c:31__list_add_valid+0x4e/0x70
  ipoib_start_xmit+0x477/0x680 [ib_ipoib]
  dev_hard_start_xmit+0xb9/0x3e0
  sch_direct_xmit+0xf9/0x250
  __qdisc_run+0x176/0x5d0
  __dev_queue_xmit+0x1f5/0xb10
  __dev_queue_xmit+0x55/0xb10

Analysis:
Two SKB are scheduled to be transmitted from two cores.
In ipoib_start_xmit, both gets NULL when calling ipoib_neigh_get.
Two calls to neigh_add_path are made. One thread takes the spin-lock
and calls ipoib_neigh_alloc which creates the neigh structure,
then (after the __path_find) the neigh is added to the path's neigh
link list. When the second thread enters the critical section it also
calls ipoib_neigh_alloc but in this case it gets the already allocated
ipoib_neigh structure, which is already linked to the path's neigh
link list and adds it again to the list. Which beside of triggering
the list, it creates a loop in the linked list. This loop leads to
endless loop inside path_rec_completion.

Solution:
Check list_empty(&neigh->list) before adding to the list.
Add a similar fix in "ipoib_multicast.c::ipoib_mcast_send"

Fixes: b63b70d87741 ('IPoIB: Use a private hash table for path lookup in xmit path')
Signed-off-by: Erez Shitrit <erezsh-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Reviewed-by: Alex Vesker <valex-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 drivers/infiniband/ulp/ipoib/ipoib_main.c      | 25 ++++++++++++++++++-------
 drivers/infiniband/ulp/ipoib/ipoib_multicast.c |  5 ++++-
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index 12b7f911f0e5..8880351df179 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -902,8 +902,8 @@ static int path_rec_start(struct net_device *dev,
 	return 0;
 }

-static void neigh_add_path(struct sk_buff *skb, u8 *daddr,
-			   struct net_device *dev)
+static struct ipoib_neigh *neigh_add_path(struct sk_buff *skb, u8 *daddr,
+					  struct net_device *dev)
 {
 	struct ipoib_dev_priv *priv = ipoib_priv(dev);
 	struct rdma_netdev *rn = netdev_priv(dev);
@@ -917,7 +917,15 @@ static void neigh_add_path(struct sk_buff *skb, u8 *daddr,
 		spin_unlock_irqrestore(&priv->lock, flags);
 		++dev->stats.tx_dropped;
 		dev_kfree_skb_any(skb);
-		return;
+		return NULL;
+	}
+
+	/* To avoid race condition, make sure that the
+	 * neigh will be added only once.
+	 */
+	if (unlikely(!list_empty(&neigh->list))) {
+		spin_unlock_irqrestore(&priv->lock, flags);
+		return neigh;
 	}

 	path = __path_find(dev, daddr + 4);
@@ -956,7 +964,7 @@ static void neigh_add_path(struct sk_buff *skb, u8 *daddr,
 			path->ah->last_send = rn->send(dev, skb, path->ah->ah,
 						       IPOIB_QPN(daddr));
 			ipoib_neigh_put(neigh);
-			return;
+			return NULL;
 		}
 	} else {
 		neigh->ah  = NULL;
@@ -973,7 +981,7 @@ static void neigh_add_path(struct sk_buff *skb, u8 *daddr,

 	spin_unlock_irqrestore(&priv->lock, flags);
 	ipoib_neigh_put(neigh);
-	return;
+	return NULL;

 err_path:
 	ipoib_neigh_free(neigh);
@@ -983,6 +991,8 @@ static void neigh_add_path(struct sk_buff *skb, u8 *daddr,

 	spin_unlock_irqrestore(&priv->lock, flags);
 	ipoib_neigh_put(neigh);
+
+	return NULL;
 }

 static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
@@ -1091,8 +1101,9 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	case htons(ETH_P_TIPC):
 		neigh = ipoib_neigh_get(dev, phdr->hwaddr);
 		if (unlikely(!neigh)) {
-			neigh_add_path(skb, phdr->hwaddr, dev);
-			return NETDEV_TX_OK;
+			neigh = neigh_add_path(skb, phdr->hwaddr, dev);
+			if (likely(!neigh))
+				return NETDEV_TX_OK;
 		}
 		break;
 	case htons(ETH_P_ARP):
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index 93e149efc1f5..9b3f47ae2016 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -816,7 +816,10 @@ void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb)
 		spin_lock_irqsave(&priv->lock, flags);
 		if (!neigh) {
 			neigh = ipoib_neigh_alloc(daddr, dev);
-			if (neigh) {
+			/* Make sure that the neigh will be added only
+			 * once to mcast list.
+			 */
+			if (neigh && list_empty(&neigh->list)) {
 				kref_get(&mcast->ah->ref);
 				neigh->ah	= mcast->ah;
 				list_add_tail(&neigh->list, &mcast->neigh_list);
--
2.15.1

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Re: [PATCH rdma-rc 0/2] RDMA fixes 2017-12-31

[Jason Gunthorpe]

On Sun, Dec 31, 2017 at 03:33:13PM +0200, Leon Romanovsky wrote:
> Hi,
> 
> There are two small fixes, one fix to mlx4_ib_alloc_mr error flow, very
> similar to commit 45e6ae7ef21b ("IB/mlx5: Fix mlx5_ib_alloc_mr error
> flow") and another fix to race condition in IPoIB revealed by Enhanced
> IPoIB tests.

Applied to for-rc

Thanks

Jason
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