Re: [PATCH 20/33] dma-mapping: clear harmful GFP_* flags in common code

[Christoph Hellwig]

On Wed, Jan 10, 2018 at 11:59:30AM +, Robin Murphy wrote:
> Just a note that if we're all happy to enshrine the "allocations are always 
> zeroed" behaviour in the API (I am too, for the record), we should remember 
> to follow up once the dust settles to update the docs and I guess just 
> #define dma_zalloc_coherent dma_alloc_coherent.

And then just remove it.  But yes, another item for the todo list..
___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [PATCH 20/33] dma-mapping: clear harmful GFP_* flags in common code

[Robin Murphy]

On 10/01/18 08:00, Christoph Hellwig wrote:
[...]

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 9f28b2fa329e..88bcb1a8211d 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -518,6 +518,13 @@ static inline void *dma_alloc_attrs(struct device *dev, 
size_t size,
if (dma_alloc_from_dev_coherent(dev, size, dma_handle, _addr))
return cpu_addr;
  
+	/*

+* Let the implementation decide on the zone to allocate from, and
+* decide on the way of zeroing the memory given that the memory
+* returned should always be zeroed.
+*/


Just a note that if we're all happy to enshrine the "allocations are 
always zeroed" behaviour in the API (I am too, for the record), we 
should remember to follow up once the dust settles to update the docs 
and I guess just #define dma_zalloc_coherent dma_alloc_coherent.


Robin.


+   flag &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM | __GFP_ZERO);
+
if (!arch_dma_alloc_attrs(, ))
return NULL;
if (!ops->alloc)


___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

[PATCH 20/33] dma-mapping: clear harmful GFP_* flags in common code

[Christoph Hellwig]

Lift the code from x86 so that we behave consistently.  In the future we
should probably warn if any of these is set.

Signed-off-by: Christoph Hellwig 
Acked-by: Jesper Nilsson 
Acked-by: Geert Uytterhoeven  [m68k]
---
 arch/cris/arch-v32/drivers/pci/dma.c  | 3 ---
 arch/h8300/kernel/dma.c   | 3 ---
 arch/m68k/kernel/dma.c| 2 --
 arch/mips/cavium-octeon/dma-octeon.c  | 3 ---
 arch/mips/loongson64/common/dma-swiotlb.c | 3 ---
 arch/mips/mm/dma-default.c| 3 ---
 arch/mips/netlogic/common/nlm-dma.c   | 3 ---
 arch/mn10300/mm/dma-alloc.c   | 3 ---
 arch/nios2/mm/dma-mapping.c   | 3 ---
 arch/powerpc/kernel/dma.c | 3 ---
 arch/x86/kernel/pci-dma.c | 2 --
 include/linux/dma-mapping.h   | 7 +++
 12 files changed, 7 insertions(+), 31 deletions(-)

diff --git a/arch/cris/arch-v32/drivers/pci/dma.c 
b/arch/cris/arch-v32/drivers/pci/dma.c
index dbbd3816cc0b..8c3802244ef3 100644
--- a/arch/cris/arch-v32/drivers/pci/dma.c
+++ b/arch/cris/arch-v32/drivers/pci/dma.c
@@ -22,9 +22,6 @@ static void *v32_dma_alloc(struct device *dev, size_t size,
 {
void *ret;
 
-   /* ignore region specifiers */
-   gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
-
if (dev == NULL || (dev->coherent_dma_mask < 0x))
gfp |= GFP_DMA;
 
diff --git a/arch/h8300/kernel/dma.c b/arch/h8300/kernel/dma.c
index 225dd0a188dc..d44ba5db4ac3 100644
--- a/arch/h8300/kernel/dma.c
+++ b/arch/h8300/kernel/dma.c
@@ -16,9 +16,6 @@ static void *dma_alloc(struct device *dev, size_t size,
 {
void *ret;
 
-   /* ignore region specifiers */
-   gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
-
if (dev == NULL || (*dev->dma_mask < 0x))
gfp |= GFP_DMA;
ret = (void *)__get_free_pages(gfp, get_order(size));
diff --git a/arch/m68k/kernel/dma.c b/arch/m68k/kernel/dma.c
index 87ef73a93856..c01b9b8f97bf 100644
--- a/arch/m68k/kernel/dma.c
+++ b/arch/m68k/kernel/dma.c
@@ -76,8 +76,6 @@ static void *m68k_dma_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
 {
void *ret;
-   /* ignore region specifiers */
-   gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
 
if (dev == NULL || (*dev->dma_mask < 0x))
gfp |= GFP_DMA;
diff --git a/arch/mips/cavium-octeon/dma-octeon.c 
b/arch/mips/cavium-octeon/dma-octeon.c
index c64bd87f0b6e..5baf79fce643 100644
--- a/arch/mips/cavium-octeon/dma-octeon.c
+++ b/arch/mips/cavium-octeon/dma-octeon.c
@@ -161,9 +161,6 @@ static void *octeon_dma_alloc_coherent(struct device *dev, 
size_t size,
 {
void *ret;
 
-   /* ignore region specifiers */
-   gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);
-
if (IS_ENABLED(CONFIG_ZONE_DMA) && dev == NULL)
gfp |= __GFP_DMA;
else if (IS_ENABLED(CONFIG_ZONE_DMA) &&
diff --git a/arch/mips/loongson64/common/dma-swiotlb.c 
b/arch/mips/loongson64/common/dma-swiotlb.c
index ef07740cee61..15388c24a504 100644
--- a/arch/mips/loongson64/common/dma-swiotlb.c
+++ b/arch/mips/loongson64/common/dma-swiotlb.c
@@ -15,9 +15,6 @@ static void *loongson_dma_alloc_coherent(struct device *dev, 
size_t size,
 {
void *ret;
 
-   /* ignore region specifiers */
-   gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);
-
if ((IS_ENABLED(CONFIG_ISA) && dev == NULL) ||
(IS_ENABLED(CONFIG_ZONE_DMA) &&
 dev->coherent_dma_mask < DMA_BIT_MASK(32)))
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index e3e94d05f0fd..237532e89919 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -93,9 +93,6 @@ static gfp_t massage_gfp_flags(const struct device *dev, 
gfp_t gfp)
 {
gfp_t dma_flag;
 
-   /* ignore region specifiers */
-   gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);
-
 #ifdef CONFIG_ISA
if (dev == NULL)
dma_flag = __GFP_DMA;
diff --git a/arch/mips/netlogic/common/nlm-dma.c 
b/arch/mips/netlogic/common/nlm-dma.c
index 0ec9d9da6d51..49c975b6aa28 100644
--- a/arch/mips/netlogic/common/nlm-dma.c
+++ b/arch/mips/netlogic/common/nlm-dma.c
@@ -47,9 +47,6 @@ static char *nlm_swiotlb;
 static void *nlm_dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
 {
-   /* ignore region specifiers */
-   gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);
-
 #ifdef CONFIG_ZONE_DMA32
if (dev->coherent_dma_mask <= DMA_BIT_MASK(32))
gfp |= __GFP_DMA32;
diff --git a/arch/mn10300/mm/dma-alloc.c b/arch/mn10300/mm/dma-alloc.c
index 86108d2496b3..e3910d4db102 100644
--- a/arch/mn10300/mm/dma-alloc.c
+++ b/arch/mn10300/mm/dma-alloc.c
@@ -37,9 +37,6 @@ static void *mn10300_dma_alloc(struct device *dev, size_t 
size,