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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 /drivers/dma/dmaengine.c
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>
Diffstat (limited to 'drivers/dma/dmaengine.c')
-rw-r--r--drivers/dma/dmaengine.c36
1 files changed, 13 insertions, 23 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;
}