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Subject[PATCH v1 2/2] drivers: dma-coherent: Move spinlock in dma_alloc_from_coherent()
Date
From: Bastian Hecht <bhecht@de.adit-jv.com>

We don't need to hold the spinlock while zeroing the allocated memory.
In case we handle big buffers this is a severe issue as other CPUs might
be spinning half a second or longer.

Signed-off-by: Bastian Hecht <bhecht@de.adit-jv.com>
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Mark Craske <Mark_Craske@mentor.com>
---
drivers/base/dma-coherent.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index abd83b7..d092df4 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -165,6 +165,7 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
int order = get_order(size);
unsigned long flags;
int pageno;
+ int dma_memory_map;

if (!dev)
return 0;
@@ -187,11 +188,12 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
*/
*dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
*ret = mem->virt_base + (pageno << PAGE_SHIFT);
- if (mem->flags & DMA_MEMORY_MAP)
+ dma_memory_map = (mem->flags & DMA_MEMORY_MAP);
+ spin_unlock_irqrestore(&mem->spinlock, flags);
+ if (dma_memory_map)
memset(*ret, 0, size);
else
memset_io(*ret, 0, size);
- spin_unlock_irqrestore(&mem->spinlock, flags);

return 1;

--
1.7.9.5

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