Commit 8324993f authored by Baochen Qiang's avatar Baochen Qiang Committed by Marek Szyprowski
Browse files

dma-mapping: fix missing clear bdr in check_ram_in_range_map() 

As discussed in [1], if 'bdr' is set once, it would never get
cleared, hence 0 is always returned.

Refactor the range check hunk into a new helper dma_find_range(),
which allows 'bdr' to be cleared in each iteration.

Link: https://lore.kernel.org/all/64931fac-085b-4ff3-9314-84bac2fa9bdb@quicinc.com/

 # [1]
Fixes: a409d960 ("dma-mapping: fix dma_addressing_limited() if dma_range_map can't cover all system RAM")
Suggested-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBaochen Qiang <quic_bqiang@quicinc.com>
Link: https://lore.kernel.org/r/20250307030350.69144-1-quic_bqiang@quicinc.com


Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
parent 2014c95a

kernel/dma/direct.c

+18 −10
Original line number Diff line number Diff line
@@ -584,6 +584,22 @@ int dma_direct_supported(struct device *dev, u64 mask) 
	return mask >= phys_to_dma_unencrypted(dev, min_mask);

}



static const struct bus_dma_region *dma_find_range(struct device *dev,

						   unsigned long start_pfn)

{

	const struct bus_dma_region *m;



	for (m = dev->dma_range_map; PFN_DOWN(m->size); m++) {

		unsigned long cpu_start_pfn = PFN_DOWN(m->cpu_start);



		if (start_pfn >= cpu_start_pfn &&

		    start_pfn - cpu_start_pfn < PFN_DOWN(m->size))

			return m;

	}



	return NULL;

}



/*

 * To check whether all ram resource ranges are covered by dma range map

 * Returns 0 when further check is needed
@@ -593,20 +609,12 @@ static int check_ram_in_range_map(unsigned long start_pfn, 
				  unsigned long nr_pages, void *data)

{

	unsigned long end_pfn = start_pfn + nr_pages;

	const struct bus_dma_region *bdr = NULL;

	const struct bus_dma_region *m;

	struct device *dev = data;



	while (start_pfn < end_pfn) {

		for (m = dev->dma_range_map; PFN_DOWN(m->size); m++) {

			unsigned long cpu_start_pfn = PFN_DOWN(m->cpu_start);

		const struct bus_dma_region *bdr;



			if (start_pfn >= cpu_start_pfn &&

			    start_pfn - cpu_start_pfn < PFN_DOWN(m->size)) {

				bdr = m;

				break;

			}

		}

		bdr = dma_find_range(dev, start_pfn);

		if (!bdr)

			return 1;