Commit e6eb307d authored Aug 02, 2006 by Chris Leech Committed by David S. Miller Aug 02, 2006

[I/OAT]: Remove CPU hotplug lock from net_dma_rebalance



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@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 9bbf28a1

net/core/dev.c

+0 −5

Original line number	Diff line number	Diff line
		@@ -3419,12 +3419,9 @@ 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;
		}

		@@ -3444,8 +3441,6 @@ static void net_dma_rebalance(void)
		i++;
		}
		rcu_read_unlock();

		unlock_cpu_hotplug();
		}

		/**

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