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platform_kernel-5.15
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[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>
This commit is contained in:
Chris Leech 2006-08-02 14:21:19 -07:00 committed by David S. Miller
parent 9bbf28a1ff
commit e6eb307d48
1 changed files with 0 additions and 5 deletions
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5
net/core/dev.c
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@ -3419,12 +3419,9 @@ static void net_dma_rebalance(void)
unsigned int cpu, i, n; unsigned int cpu, i, n;
struct dma_chan *chan; struct dma_chan *chan;
lock_cpu_hotplug();
if (net_dma_count == 0) { if (net_dma_count == 0) {
for_each_online_cpu(cpu) for_each_online_cpu(cpu)
rcu_assign_pointer(per_cpu(softnet_data.net_dma, cpu), NULL); rcu_assign_pointer(per_cpu(softnet_data.net_dma, cpu), NULL);
unlock_cpu_hotplug();
return; return;
} }
@ -3444,8 +3441,6 @@ static void net_dma_rebalance(void)
i++; i++;
} }
rcu_read_unlock(); rcu_read_unlock();
unlock_cpu_hotplug();
} }
/** /**