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@xxxxxxxxxxxx>
---
Changes since v1:
- Use DEFINE_SHOW_ATTRIBUTE
- Add Documentation
Documentation/DMA-API.txt | 3 +++
kernel/dma/debug.c | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+)
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index e133ccd60228..78114ee63057 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -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.
diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 23cf5361bcf1..b4827b1c9070 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -144,6 +144,7 @@ static struct dentry *num_free_entries_dent __read_mostly;
static struct dentry *min_free_entries_dent __read_mostly;
static struct dentry *nr_total_entries_dent __read_mostly;
static struct dentry *filter_dent __read_mostly;
+static struct dentry *dump_dent __read_mostly;
/* per-driver filter related state */
@@ -840,6 +841,36 @@ 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 int dma_debug_fs_init(void)
{
dma_debug_dent = debugfs_create_dir("dma-api", NULL);
@@ -894,6 +925,11 @@ static int dma_debug_fs_init(void)
if (!filter_dent)
goto out_err;
+ dump_dent = debugfs_create_file("dump", 0444,
+ dma_debug_dent, NULL, &dump_fops);
+ if (!dump_dent)
+ goto out_err;
+
return 0;
out_err:
--
2.19.2
