Commit 0a3b192c authored by Corentin Labbe's avatar Corentin Labbe Committed by Christoph Hellwig
Browse files

dma-debug: add dumping facility via debugfs 



While debugging a DMA mapping leak, I needed to access
debug_dma_dump_mappings() but easily from user space.

This patch adds a /sys/kernel/debug/dma-api/dump file which contain all
current DMA mapping.

Signed-off-by: default avatarCorentin Labbe <clabbe@baylibre.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 8e4d81b9

Documentation/DMA-API.txt

+3 −0
Original line number Diff line number Diff line
@@ -696,6 +696,9 @@ dma-api/disabled This read-only file contains the character 'Y' 
				happen when it runs out of memory or if it was

				disabled at boot time



dma-api/dump			This read-only file contains current DMA

				mappings.



dma-api/error_count		This file is read-only and shows the total

				numbers of errors found.

kernel/dma/debug.c

+28 −0
Original line number Diff line number Diff line
@@ -829,6 +829,33 @@ static const struct file_operations filter_fops = { 
	.llseek = default_llseek,

};



static int dump_show(struct seq_file *seq, void *v)

{

	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) {

			seq_printf(seq,

				   "%s %s %s idx %d P=%llx N=%lx D=%llx L=%llx %s %s\n",

				   dev_name(entry->dev),

				   dev_driver_string(entry->dev),

				   type2name[entry->type], idx,

				   phys_addr(entry), entry->pfn,

				   entry->dev_addr, entry->size,

				   dir2name[entry->direction],

				   maperr2str[entry->map_err_type]);

		}

		spin_unlock_irqrestore(&bucket->lock, flags);

	}

	return 0;

}

DEFINE_SHOW_ATTRIBUTE(dump);



static void dma_debug_fs_init(void)

{

	struct dentry *dentry = debugfs_create_dir("dma-api", NULL);
@@ -841,6 +868,7 @@ static void dma_debug_fs_init(void) 
	debugfs_create_u32("min_free_entries", 0444, dentry, &min_free_entries);

	debugfs_create_u32("nr_total_entries", 0444, dentry, &nr_total_entries);

	debugfs_create_file("driver_filter", 0644, dentry, NULL, &filter_fops);

	debugfs_create_file("dump", 0444, dentry, NULL, &dump_fops);

}



static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)

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