IB/IPoIB: Fix kernel panic on multicast flow

ipoib_mcast_restart_task calls ipoib_mcast_remove_list with the
parameter mcast->dev. That mcast is a temporary (used as an iterator)
variable that may be uninitialized.
There is no need to send the variable dev to the function, as each mcast
has its dev as a member in the mcast struct.

This causes the next panic:
RIP: 0010: ipoib_mcast_leave+0x6d/0xf0 [ib_ipoib]
RSP: 0018: EFLAGS: 00010246
RAX: f0201 RBX: 24e00 RCX: 00000
....
....
Stack:
Call Trace:
	ipoib_mcast_remove_list+0x3a/0x70 [ib_ipoib]
	ipoib_mcast_restart_task+0x3bb/0x520 [ib_ipoib]
	process_one_work+0x164/0x470
	worker_thread+0x11d/0x420
	...

Fixes: 5a0e81f6f483 ('IB/IPoIB: factor out common multicast list removal code')
Signed-off-by: Erez Shitrit <erezsh@mellanox.com>
Reported-by: Doron Tsur <doront@mellanox.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/ipoib/ipoib.h

@@ -548,7 +548,7 @@ void ipoib_path_iter_read(struct ipoib_path_iter *iter,
 
 int ipoib_mcast_attach(struct net_device *dev, u16 mlid,
 		       union ib_gid *mgid, int set_qkey);
-void ipoib_mcast_remove_list(struct net_device *dev, struct list_head *remove_list);
+void ipoib_mcast_remove_list(struct list_head *remove_list);
 void ipoib_check_and_add_mcast_sendonly(struct ipoib_dev_priv *priv, u8 *mgid,
 				struct list_head *remove_list);
 

drivers/infiniband/ulp/ipoib/ipoib_main.c

@@ -1150,7 +1150,6 @@ static void __ipoib_reap_neigh(struct ipoib_dev_priv *priv)
 	unsigned long flags;
 	int i;
 	LIST_HEAD(remove_list);
-	struct net_device *dev = priv->dev;
 
 	if (test_bit(IPOIB_STOP_NEIGH_GC, &priv->flags))
 		return;
@@ -1196,7 +1195,7 @@ static void __ipoib_reap_neigh(struct ipoib_dev_priv *priv)
 
 out_unlock:
 	spin_unlock_irqrestore(&priv->lock, flags);
-	ipoib_mcast_remove_list(dev, &remove_list);
+	ipoib_mcast_remove_list(&remove_list);
 }
 
 static void ipoib_reap_neigh(struct work_struct *work)

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

@@ -723,12 +723,12 @@ void ipoib_check_and_add_mcast_sendonly(struct ipoib_dev_priv *priv, u8 *mgid,
 	}
 }
 
-void ipoib_mcast_remove_list(struct net_device *dev, struct list_head *remove_list)
+void ipoib_mcast_remove_list(struct list_head *remove_list)
 {
 	struct ipoib_mcast *mcast, *tmcast;
 
 	list_for_each_entry_safe(mcast, tmcast, remove_list, list) {
-		ipoib_mcast_leave(dev, mcast);
+		ipoib_mcast_leave(mcast->dev, mcast);
 		ipoib_mcast_free(mcast);
 	}
 }
@@ -839,7 +839,7 @@ void ipoib_mcast_dev_flush(struct net_device *dev)
 		if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
 			wait_for_completion(&mcast->done);
 
-	ipoib_mcast_remove_list(dev, &remove_list);
+	ipoib_mcast_remove_list(&remove_list);
 }
 
 static int ipoib_mcast_addr_is_valid(const u8 *addr, const u8 *broadcast)
@@ -965,7 +965,7 @@ void ipoib_mcast_restart_task(struct work_struct *work)
 		if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
 			wait_for_completion(&mcast->done);
 
-	ipoib_mcast_remove_list(mcast->dev, &remove_list);
+	ipoib_mcast_remove_list(&remove_list);
 
 	/*
 	 * Double check that we are still up