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-rw-r--r--lib/dma-debug.c24
1 files changed, 19 insertions, 5 deletions
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index d3e06a5e981e..d87a17a819d0 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -1085,13 +1085,27 @@ void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
ref.dev = dev;
ref.dev_addr = dma_addr;
bucket = get_hash_bucket(&ref, &flags);
- entry = bucket_find_exact(bucket, &ref);
- if (!entry)
- goto out;
+ list_for_each_entry(entry, &bucket->list, list) {
+ if (!exact_match(&ref, entry))
+ continue;
+
+ /*
+ * The same physical address can be mapped multiple
+ * times. Without a hardware IOMMU this results in the
+ * same device addresses being put into the dma-debug
+ * hash multiple times too. This can result in false
+ * positives being reported. Therefore we implement a
+ * best-fit algorithm here which updates the first entry
+ * from the hash which fits the reference value and is
+ * not currently listed as being checked.
+ */
+ if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
+ entry->map_err_type = MAP_ERR_CHECKED;
+ break;
+ }
+ }
- entry->map_err_type = MAP_ERR_CHECKED;
-out:
put_hash_bucket(bucket, &flags);
}
EXPORT_SYMBOL(debug_dma_mapping_error);