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authorChristoph Lameter <cl@linux-foundation.org>2009-10-03 14:48:23 +0400
committerTejun Heo <tj@kernel.org>2009-10-03 14:48:23 +0400
commite7dcaa4755e35d7540bf19f316f8798357c53fa0 (patch)
tree69c41151378213382199b577f2bc7b0d8bd1cc22
parentca0c9584b1f16bd5911893647cb7f1be82e60554 (diff)
downloadlinux-e7dcaa4755e35d7540bf19f316f8798357c53fa0.tar.xz
this_cpu: Eliminate get/put_cpu
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>
-rw-r--r--drivers/dma/dmaengine.c36
-rw-r--r--drivers/net/veth.c7
2 files changed, 16 insertions, 27 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index bd0b248de2cf..51d7480d3a92 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -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;
}
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index ade5b344f75d..0c4a81124257 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -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;