From: Sebastian Andrzej Siewior Date: Wed, 11 Apr 2018 13:34:26 +0200 Subject: [PATCH] IB/ipoib: replace local_irq_disable() with proper locking Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.16/older/patches-4.16.8-rt3.tar.xz 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 --- 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); } }