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Subject[PATCH v2 2/8] dma-debug: Expose nr_total_entries in debugfs
Expose nr_total_entries in debugfs, so that {num,min}_free_entries
become even more meaningful to users interested in current/maximum
utilisation. This becomes even more relevant once nr_total_entries
may change at runtime beyond just the existing AMD GART debug code.

Suggested-by: John Garry <>
Signed-off-by: Robin Murphy <>

v2: New

Documentation/DMA-API.txt | 3 +++
kernel/dma/debug.c | 7 +++++++
2 files changed, 10 insertions(+)

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index ac66ae2509a9..6bdb095393b0 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -723,6 +723,9 @@ dma-api/min_free_entries This read-only file can be read to get the
dma-api/num_free_entries The current number of free dma_debug_entries
in the allocator.

+dma-api/nr_total_entries The total number of dma_debug_entries in the
+ allocator, both free and used.
dma-api/driver-filter You can write a name of a driver into this file
to limit the debug output to requests from that
particular driver. Write an empty string to
diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 91b84140e4a5..29486eb9d1dc 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -144,6 +144,7 @@ static struct dentry *show_all_errors_dent __read_mostly;
static struct dentry *show_num_errors_dent __read_mostly;
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;

/* per-driver filter related state */
@@ -928,6 +929,12 @@ static int dma_debug_fs_init(void)
if (!min_free_entries_dent)
goto out_err;

+ nr_total_entries_dent = debugfs_create_u32("nr_total_entries", 0444,
+ dma_debug_dent,
+ &nr_total_entries);
+ if (!nr_total_entries_dent)
+ goto out_err;
filter_dent = debugfs_create_file("driver_filter", 0644,
dma_debug_dent, NULL, &filter_fops);
if (!filter_dent)
 \ /
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