[PATCH] I/OAT: remove CPU hotplug lock from net_dma_rebalance

[Chris Leech]

Remove the lock_cpu_hotplug()/unlock_cpu_hotplug() calls from net_dma_rebalance

The lock_cpu_hotplug()/unlock_cpu_hotplug() sequence in net_dma_rebalance
is both incorrect (as pointed out by David Miller) because lock_cpu_hotplug()
may sleep while the net_dma_event_lock spinlock is held, and unnecessary (as
pointed out by Andrew Morton) as spin_lock() disables preemption which
protects from CPU hotplug events.

Signed-off-by: Chris Leech <christopher.leech@xxxxxxxxx>
---

 net/core/dev.c |    5 -----
1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 4d2b516..780d770 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3429,12 +3429,9 @@ static void net_dma_rebalance(void)
       unsigned int cpu, i, n;
       struct dma_chan *chan;

-       lock_cpu_hotplug();
-
       if (net_dma_count == 0) {
               for_each_online_cpu(cpu)

rcu_assign_pointer(per_cpu(softnet_data.net_dma, cpu), NULL);
-               unlock_cpu_hotplug();
               return;
       }

@@ -3454,8 +3451,6 @@ static void net_dma_rebalance(void)
               i++;
       }
       rcu_read_unlock();
-
-       unlock_cpu_hotplug();
}

/**
-
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