From dd01c75f1df311793de6ef217c72036552000c9a Mon Sep 17 00:00:00 2001 From: Bastian Hecht Date: Wed, 28 Sep 2016 08:51:57 +0100 Subject: [PATCH] drivers: dma-coherent: Move spinlock in dma_alloc_from_coherent() 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 Signed-off-by: George G. Davis Signed-off-by: Mark Craske Signed-off-by: Greg Kroah-Hartman --- 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 2789f7a95b93..640a7e63c453 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; -- 2.20.1