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16 September 2024, 20:19:31 UTC
Revision 2995b8002cefc7b0b00b8f9a0ce36601a8c390c0 authored by Robin Murphy on 15 August 2022, 19:28:40 UTC, committed by Christoph Hellwig on 07 September 2022, 08:38:16 UTC 
dma-debug: improve search for partial syncs
 
When bucket_find_contains() tries to find the original entry for a
partial sync, it manages to constrain its search in a way that is both
too restrictive and not restrictive enough. A driver which only uses
single mappings rather than scatterlists might not set max_seg_size, but
could still technically perform a partial sync at an offset of more than
64KB into a sufficiently large mapping, so we could stop searching too
early before reaching a legitimate entry. Conversely, if no valid entry
is present and max_range is large enough, we can pointlessly search
buckets that we've already searched, or that represent an impossible
wrapping around the bottom of the address space. At worst, the
(legitimate) case of max_seg_size == UINT_MAX can make the loop
infinite.

Replace the fragile and frankly hard-to-follow "range" logic with a
simple counted loop for the number of possible hash buckets below the
given address.

Reported-by: Yunfei Wang <yf.wang@mediatek.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
1 parent 81c12e9
History
Tip revision: 2995b8002cefc7b0b00b8f9a0ce36601a8c390c0 authored by Robin Murphy on 15 August 2022, 19:28:40 UTC
dma-debug: improve search for partial syncs
Tip revision: 2995b80
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