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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: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Corentin Labbe 2019-01-18 13:44:18 +00:00 committed by Christoph Hellwig
parent 8e4d81b98b
commit 0a3b192c26
2 changed files with 31 additions and 0 deletions
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3
Documentation/DMA-API.txt
View File

@ -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.

28
kernel/dma/debug.c
View File

@ -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)