2022-09-01 14:47:19

by Fabio M. De Francesco

Subject: [PATCH] swiotlb: Replace kmap_atomic() with memcpy_{from,to}_page()

The use of kmap_atomic() is being deprecated in favor of
kmap_local_page(), which can also be used in atomic context (including
interrupts).

Replace kmap_atomic() with kmap_local_page(). Instead of open coding
mapping, memcpy(), and un-mapping, use the memcpy_{from,to}_page() helper.

Suggested-by: Ira Weiny <[email protected]>
Signed-off-by: Fabio M. De Francesco <[email protected]>
---
kernel/dma/swiotlb.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index c5a9190b218f..a28ac23ad8db 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -549,9 +549,8 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size
}

if (PageHighMem(pfn_to_page(pfn))) {
- /* The buffer does not have a mapping. Map it in and copy */
unsigned int offset = orig_addr & ~PAGE_MASK;
- char *buffer;
+ struct page *page;
unsigned int sz = 0;
unsigned long flags;

@@ -559,12 +558,11 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size
sz = min_t(size_t, PAGE_SIZE - offset, size);

local_irq_save(flags);
- buffer = kmap_atomic(pfn_to_page(pfn));
+ page = pfn_to_page(pfn);
if (dir == DMA_TO_DEVICE)
- memcpy(vaddr, buffer + offset, sz);
+ memcpy_from_page(vaddr, page, offset, sz);
else
- memcpy(buffer + offset, vaddr, sz);
- kunmap_atomic(buffer);
+ memcpy_to_page(page, offset, vaddr, sz);
local_irq_restore(flags);

size -= sz;
--
2.37.2

2022-09-20 07:48:49

by Christoph Hellwig

Subject: Re: [PATCH] swiotlb: Replace kmap_atomic() with memcpy_{from,to}_page()

Thanks,

applied to the dma-mapping tree for 6.1.