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SubjectRe: [PATCH 0/16] DMA-API debugging facility v2
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This adds a function to dump the DMA mappings that the debugging code is
aware of -- either for a single device, or for _all_ devices.

This can be useful for debugging -- sticking a call to it in the DMA
page fault handler, for example, to see if the faulting address _should_
be mapped or not, and hence work out whether it's IOMMU bugs we're
seeing, or driver bugs.

I'd also like to make it answer the question 'should address X be mapped
for device Y', but I'll get to that next.

Do we have a %pX format for printing dma_addr_t yet?

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
index 8a8aae4..5f4fc9f 100644
--- a/include/linux/dma-debug.h
+++ b/include/linux/dma-debug.h
@@ -75,6 +75,8 @@ extern void debug_dma_sync_sg_for_device(struct device *dev,
struct scatterlist *sg,
int nelems, int direction);

+extern void debug_dma_dump_mappings(struct device *dev);
+
#else /* CONFIG_DMA_API_DEBUG */

static inline void dma_debug_init(u32 num_entries)
@@ -155,6 +157,10 @@ static inline void debug_dma_sync_sg_for_device(struct device *dev,
{
}

+static inline void debug_dma_dump_mappings(struct device *dev)
+{
+}
+
#endif /* CONFIG_DMA_API_DEBUG */

#endif /* __DMA_DEBUG_H */
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 469e5b9..127d108 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -191,6 +191,36 @@ static void hash_bucket_del(struct dma_debug_entry *entry)
}

/*
+ * Dump mapping entries for debugging purposes
+ */
+void debug_dma_dump_mappings(struct device *dev)
+{
+ int idx;
+
+ for (idx = 0; idx < HASH_SIZE; idx++) {
+ struct hash_bucket *bucket = &dma_entry_hash[idx];
+ struct dma_debug_entry *entry;
+ unsigned long flags;
+
+ spin_lock_irqsave(&bucket->lock, flags);
+
+ list_for_each_entry(entry, &bucket->list, list) {
+ if (!dev || dev == entry->dev) {
+ dev_info(entry->dev,
+ "%s idx %d P=%Lx D=%Lx L=%Lx %s\n",
+ type2name[entry->type], idx,
+ (unsigned long long)entry->paddr,
+ entry->dev_addr, entry->size,
+ dir2name[entry->direction]);
+ }
+ }
+
+ spin_unlock_irqrestore(&bucket->lock, flags);
+ }
+}
+EXPORT_SYMBOL(debug_dma_dump_mappings);
+
+/*
* Wrapper function for adding an entry to the hash.
* This function takes care of locking itself.
*/

--
David Woodhouse Open Source Technology Centre
David.Woodhouse@intel.com Intel Corporation



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