patches/IB-ipoib-replace-local_irq_disable-with-proper-locki.patch

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 11 Apr 2018 13:34:26 +0200
Subject: [PATCH] IB/ipoib: replace local_irq_disable() with proper locking

Commit 78bfe0b5b67f ("IPoIB: Take dev->xmit_lock around mc_list accesses")
introduced xmit_lock lock in ipoib_mcast_restart_task() and commit
932ff279a43a ("[NET]: Add netif_tx_lock") preserved the locking order while
dev->xmit_lock has been replaced with a helper. The netif_tx_lock should
not be acquired with disabled interrupts because it is meant to be a BH
disabling lock.

The priv->lock is always acquired with interrupts disabled. The only
place where netif_addr_lock() and priv->lock nest ist
ipoib_mcast_restart_task(). By reversing the lock order and taking
netif_addr lock with bottom halfs disabled it is possible to get rid of
the local_irq_save() completely.

This requires to take priv->lock with spin_lock_irq() inside the netif_addr
locked section. It's safe to do so because the caller is either a worker
function or __ipoib_ib_dev_flush() which are both calling with interrupts
enabled.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/infiniband/ulp/ipoib/ipoib_multicast.c |   15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -886,7 +886,6 @@ void ipoib_mcast_restart_task(struct wor
 	struct netdev_hw_addr *ha;
 	struct ipoib_mcast *mcast, *tmcast;
 	LIST_HEAD(remove_list);
-	unsigned long flags;
 	struct ib_sa_mcmember_rec rec;
 
 	if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
@@ -898,9 +897,8 @@ void ipoib_mcast_restart_task(struct wor
 
 	ipoib_dbg_mcast(priv, "restarting multicast task\n");
 
-	local_irq_save(flags);
-	netif_addr_lock(dev);
-	spin_lock(&priv->lock);
+	netif_addr_lock_bh(dev);
+	spin_lock_irq(&priv->lock);
 
 	/*
 	 * Unfortunately, the networking core only gives us a list of all of
@@ -978,9 +976,8 @@ void ipoib_mcast_restart_task(struct wor
 		}
 	}
 
-	spin_unlock(&priv->lock);
-	netif_addr_unlock(dev);
-	local_irq_restore(flags);
+	spin_unlock_irq(&priv->lock);
+	netif_addr_unlock_bh(dev);
 
 	ipoib_mcast_remove_list(&remove_list);
 
@@ -988,9 +985,9 @@ void ipoib_mcast_restart_task(struct wor
 	 * Double check that we are still up
 	 */
 	if (test_bit(IPOIB_FLAG_OPER_UP, &priv->flags)) {
-		spin_lock_irqsave(&priv->lock, flags);
+		spin_lock_irq(&priv->lock);
 		__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
-		spin_unlock_irqrestore(&priv->lock, flags);
+		spin_unlock_irq(&priv->lock);
 	}
 }