Re: [PATCH 2/2] dma: remove unsupported gfp_mask parameter from dma_alloc_from_contiguous()

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On Mon, 9 Jul 2018 13:20 Marek Szyprowski, <m.szyprowski@xxxxxxxxxxx> wrote:
The CMA memory allocator doesn't support standard gfp flags for memory
allocation, so there is no point having it as a parameter for
dma_alloc_from_contiguous() function. Replace it by a boolean no_warn
argument, which covers all the underlaying cma_alloc() function supports.

This will help to avoid giving false feeling that this function supports
standard gfp flags and callers can pass __GFP_ZERO to get zeroed buffer,
what has already been an issue: see commit dd65a941f6ba ("arm64:
dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag").

Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>

Acked-by: Michał Nazarewicz <mina86@xxxxxxxxxx>

---
 arch/arm/mm/dma-mapping.c      | 5 +++--
 arch/arm64/mm/dma-mapping.c    | 4 ++--
 arch/xtensa/kernel/pci-dma.c   | 2 +-
 drivers/iommu/amd_iommu.c      | 2 +-
 drivers/iommu/intel-iommu.c    | 3 ++-
 include/linux/dma-contiguous.h | 4 ++--
 kernel/dma/contiguous.c        | 7 +++----
 kernel/dma/direct.c            | 3 ++-
 8 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index be0fa7e39c26..121c6c3ba9e0 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -594,7 +594,7 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
        struct page *page;
        void *ptr = NULL;

-       page = dma_alloc_from_contiguous(dev, count, order, gfp);
+       page = dma_alloc_from_contiguous(dev, count, order, gfp & __GFP_NOWARN);
        if (!page)
                return NULL;

@@ -1294,7 +1294,8 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size,
                unsigned long order = get_order(size);
                struct page *page;

-               page = dma_alloc_from_contiguous(dev, count, order, gfp);
+               page = dma_alloc_from_contiguous(dev, count, order,
+                                                gfp & __GFP_NOWARN);
                if (!page)
                        goto error;

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 61e93f0b5482..072c51fb07d7 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -355,7 +355,7 @@ static int __init atomic_pool_init(void)

        if (dev_get_cma_area(NULL))
                page = dma_alloc_from_contiguous(NULL, nr_pages,
-                                                pool_size_order, GFP_KERNEL);
+                                                pool_size_order, false);
        else
                page = alloc_pages(GFP_DMA32, pool_size_order);

@@ -573,7 +573,7 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
                struct page *page;

                page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
-                                                get_order(size), gfp);
+                                       get_order(size), gfp & __GFP_NOWARN);
                if (!page)
                        return NULL;

diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
index ba4640cc0093..b2c7ba91fb08 100644
--- a/arch/xtensa/kernel/pci-dma.c
+++ b/arch/xtensa/kernel/pci-dma.c
@@ -137,7 +137,7 @@ static void *xtensa_dma_alloc(struct device *dev, size_t size,

        if (gfpflags_allow_blocking(flag))
                page = dma_alloc_from_contiguous(dev, count, get_order(size),
-                                                flag);
+                                                flag & __GFP_NOWARN);

        if (!page)
                page = alloc_pages(flag, get_order(size));
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 64cfe854e0f5..5ec97ffb561a 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2622,7 +2622,7 @@ static void *alloc_coherent(struct device *dev, size_t size,
                        return NULL;

                page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
-                                                get_order(size), flag);
+                                       get_order(size), flag & __GFP_NOWARN);
                if (!page)
                        return NULL;
        }
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 869321c594e2..dd2d343428ab 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3746,7 +3746,8 @@ static void *intel_alloc_coherent(struct device *dev, size_t size,
        if (gfpflags_allow_blocking(flags)) {
                unsigned int count = size >> PAGE_SHIFT;

-               page = dma_alloc_from_contiguous(dev, count, order, flags);
+               page = dma_alloc_from_contiguous(dev, count, order,
+                                                flags & __GFP_NOWARN);
                if (page && iommu_no_mapping(dev) &&
                    page_to_phys(page) + size > dev->coherent_dma_mask) {
                        dma_release_from_contiguous(dev, page, count);
diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h
index 3c5a4cb3eb95..f247e8aa5e3d 100644
--- a/include/linux/dma-contiguous.h
+++ b/include/linux/dma-contiguous.h
@@ -112,7 +112,7 @@ static inline int dma_declare_contiguous(struct device *dev, phys_addr_t size,
 }

 struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
-                                      unsigned int order, gfp_t gfp_mask);
+                                      unsigned int order, bool no_warn);
 bool dma_release_from_contiguous(struct device *dev, struct page *pages,
                                 int count);

@@ -145,7 +145,7 @@ int dma_declare_contiguous(struct device *dev, phys_addr_t size,

 static inline
 struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
-                                      unsigned int order, gfp_t gfp_mask)
+                                      unsigned int order, bool no_warn)
 {
        return NULL;
 }
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 19ea5d70150c..286d82329eb0 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -178,7 +178,7 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
  * @dev:   Pointer to device for which the allocation is performed.
  * @count: Requested number of pages.
  * @align: Requested alignment of pages (in PAGE_SIZE order).
- * @gfp_mask: GFP flags to use for this allocation.
+ * @no_warn: Avoid printing message about failed allocation.
  *
  * This function allocates memory buffer for specified device. It uses
  * device specific contiguous memory area if available or the default
@@ -186,13 +186,12 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
  * function.
  */
 struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
-                                      unsigned int align, gfp_t gfp_mask)
+                                      unsigned int align, bool no_warn)
 {
        if (align > CONFIG_CMA_ALIGNMENT)
                align = CONFIG_CMA_ALIGNMENT;

-       return cma_alloc(dev_get_cma_area(dev), count, align,
-                        gfp_mask & __GFP_NOWARN);
+       return cma_alloc(dev_get_cma_area(dev), count, align, no_warn);
 }

 /**
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 8be8106270c2..e0241beeb645 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -78,7 +78,8 @@ void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 again:
        /* CMA can be used only in the context which permits sleeping */
        if (gfpflags_allow_blocking(gfp)) {
-               page = dma_alloc_from_contiguous(dev, count, page_order, gfp);
+               page = dma_alloc_from_contiguous(dev, count, page_order,
+                                                gfp & __GFP_NOWARN);
                if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
                        dma_release_from_contiguous(dev, page, count);
                        page = NULL;
--
2.17.1


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