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this_cpu: Eliminate get/put_cpu

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There are cases where we can use this_cpu_ptr and as the result
of using this_cpu_ptr() we no longer need to determine the
currently executing cpu.

In those places no get/put_cpu combination is needed anymore.
The local cpu variable can be eliminated.

Preemption still needs to be disabled and enabled since the
modifications of the per cpu variables is not atomic. There may
be multiple per cpu variables modified and those must all
be from the same processor.

Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
cc: Eric Biederman <ebiederm@aristanetworks.com>
cc: Stephen Hemminger <shemminger@vyatta.com>
cc: David L Stevens <dlstevens@us.ibm.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Christoph Lameter 2009-10-03 19:48:23 +09:00 committed by Tejun Heo
parent ca0c9584b1
commit e7dcaa4755
2 changed files with 16 additions and 27 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

36
drivers/dma/dmaengine.c
View file

@ -326,14 +326,7 @@ arch_initcall(dma_channel_table_init);
*/
struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
{
struct dma_chan *chan;
int cpu;
cpu = get_cpu();
chan = per_cpu_ptr(channel_table[tx_type], cpu)->chan;
put_cpu();
return chan;
return this_cpu_read(channel_table[tx_type]->chan);
}
EXPORT_SYMBOL(dma_find_channel);
@ -847,7 +840,6 @@ dma_async_memcpy_buf_to_buf(struct dma_chan *chan, void *dest,
struct dma_async_tx_descriptor *tx;
dma_addr_t dma_dest, dma_src;
dma_cookie_t cookie;
int cpu;
unsigned long flags;
dma_src = dma_map_single(dev->dev, src, len, DMA_TO_DEVICE);
@ -866,10 +858,10 @@ dma_async_memcpy_buf_to_buf(struct dma_chan *chan, void *dest,
tx->callback = NULL;
cookie = tx->tx_submit(tx);
cpu = get_cpu();
per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
per_cpu_ptr(chan->local, cpu)->memcpy_count++;
put_cpu();
preempt_disable();
__this_cpu_add(chan->local->bytes_transferred, len);
__this_cpu_inc(chan->local->memcpy_count);
preempt_enable();
return cookie;
}
@ -896,7 +888,6 @@ dma_async_memcpy_buf_to_pg(struct dma_chan *chan, struct page *page,
struct dma_async_tx_descriptor *tx;
dma_addr_t dma_dest, dma_src;
dma_cookie_t cookie;
int cpu;
unsigned long flags;
dma_src = dma_map_single(dev->dev, kdata, len, DMA_TO_DEVICE);
@ -913,10 +904,10 @@ dma_async_memcpy_buf_to_pg(struct dma_chan *chan, struct page *page,
tx->callback = NULL;
cookie = tx->tx_submit(tx);
cpu = get_cpu();
per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
per_cpu_ptr(chan->local, cpu)->memcpy_count++;
put_cpu();
preempt_disable();
__this_cpu_add(chan->local->bytes_transferred, len);
__this_cpu_inc(chan->local->memcpy_count);
preempt_enable();
return cookie;
}
@ -945,7 +936,6 @@ dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
struct dma_async_tx_descriptor *tx;
dma_addr_t dma_dest, dma_src;
dma_cookie_t cookie;
int cpu;
unsigned long flags;
dma_src = dma_map_page(dev->dev, src_pg, src_off, len, DMA_TO_DEVICE);
@ -963,10 +953,10 @@ dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
tx->callback = NULL;
cookie = tx->tx_submit(tx);
cpu = get_cpu();
per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
per_cpu_ptr(chan->local, cpu)->memcpy_count++;
put_cpu();
preempt_disable();
__this_cpu_add(chan->local->bytes_transferred, len);
__this_cpu_inc(chan->local->memcpy_count);
preempt_enable();
return cookie;
}

7
drivers/net/veth.c
View file

@ -153,7 +153,7 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
struct net_device *rcv = NULL;
struct veth_priv *priv, *rcv_priv;
struct veth_net_stats *stats, *rcv_stats;
int length, cpu;
int length;
skb_orphan(skb);
@ -161,9 +161,8 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
rcv = priv->peer;
rcv_priv = netdev_priv(rcv);
cpu = smp_processor_id();
stats = per_cpu_ptr(priv->stats, cpu);
rcv_stats = per_cpu_ptr(rcv_priv->stats, cpu);
stats = this_cpu_ptr(priv->stats);
rcv_stats = this_cpu_ptr(rcv_priv->stats);
if (!(rcv->flags & IFF_UP))
goto tx_drop;