[PATCH v1 2/2] drivers: dma-coherent: Move spinlock in dma_alloc_from_coherent()

[Mark Craske]

From: Bastian Hecht <bhe...@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 <bhe...@de.adit-jv.com>
Signed-off-by: George G. Davis <george_da...@mentor.com>
Signed-off-by: Mark Craske <mark_cra...@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