linux-kernel - [PATCH 1/4] dma-buf: Rename and expose debugfs symbols

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Message-ID: <20250414225227.3642618-2-tjmercier@google.com>
Date: Mon, 14 Apr 2025 22:52:24 +0000
From: "T.J. Mercier" <tjmercier@...gle.com>
To: sumit.semwal@...aro.org, christian.koenig@....com, ast@...nel.org, 
	daniel@...earbox.net, andrii@...nel.org, martin.lau@...ux.dev, 
	skhan@...uxfoundation.org
Cc: linux-kernel@...r.kernel.org, linux-media@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org, 
	linux-doc@...r.kernel.org, bpf@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, android-mm@...gle.com, simona@...ll.ch, 
	corbet@....net, eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev, 
	john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me, 
	jolsa@...nel.org, mykolal@...com, "T.J. Mercier" <tjmercier@...gle.com>
Subject: [PATCH 1/4] dma-buf: Rename and expose debugfs symbols

Expose the debugfs list and mutex so they are usable for the creation of
a BPF iterator for dmabufs. Rename the symbols so it's clear they
contain dmabufs and not some other type.

Signed-off-by: T.J. Mercier <tjmercier@...gle.com>
---
 drivers/dma-buf/dma-buf.c | 22 +++++++++++-----------
 include/linux/dma-buf.h   |  6 ++++++
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 5baa83b85515..affb47eb8629 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -36,14 +36,14 @@
 static inline int is_dma_buf_file(struct file *);
 
 #if IS_ENABLED(CONFIG_DEBUG_FS)
-static DEFINE_MUTEX(debugfs_list_mutex);
-static LIST_HEAD(debugfs_list);
+DEFINE_MUTEX(dmabuf_debugfs_list_mutex);
+LIST_HEAD(dmabuf_debugfs_list);
 
 static void __dma_buf_debugfs_list_add(struct dma_buf *dmabuf)
 {
-	mutex_lock(&debugfs_list_mutex);
-	list_add(&dmabuf->list_node, &debugfs_list);
-	mutex_unlock(&debugfs_list_mutex);
+	mutex_lock(&dmabuf_debugfs_list_mutex);
+	list_add(&dmabuf->list_node, &dmabuf_debugfs_list);
+	mutex_unlock(&dmabuf_debugfs_list_mutex);
 }
 
 static void __dma_buf_debugfs_list_del(struct dma_buf *dmabuf)
@@ -51,9 +51,9 @@ static void __dma_buf_debugfs_list_del(struct dma_buf *dmabuf)
 	if (!dmabuf)
 		return;
 
-	mutex_lock(&debugfs_list_mutex);
+	mutex_lock(&dmabuf_debugfs_list_mutex);
 	list_del(&dmabuf->list_node);
-	mutex_unlock(&debugfs_list_mutex);
+	mutex_unlock(&dmabuf_debugfs_list_mutex);
 }
 #else
 static void __dma_buf_debugfs_list_add(struct dma_buf *dmabuf)
@@ -1630,7 +1630,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 	size_t size = 0;
 	int ret;
 
-	ret = mutex_lock_interruptible(&debugfs_list_mutex);
+	ret = mutex_lock_interruptible(&dmabuf_debugfs_list_mutex);
 
 	if (ret)
 		return ret;
@@ -1639,7 +1639,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 	seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\tname\n",
 		   "size", "flags", "mode", "count", "ino");
 
-	list_for_each_entry(buf_obj, &debugfs_list, list_node) {
+	list_for_each_entry(buf_obj, &dmabuf_debugfs_list, list_node) {
 
 		ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);
 		if (ret)
@@ -1676,11 +1676,11 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 
 	seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
 
-	mutex_unlock(&debugfs_list_mutex);
+	mutex_unlock(&dmabuf_debugfs_list_mutex);
 	return 0;
 
 error_unlock:
-	mutex_unlock(&debugfs_list_mutex);
+	mutex_unlock(&dmabuf_debugfs_list_mutex);
 	return ret;
 }
 
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 36216d28d8bd..7754608453dc 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -18,6 +18,7 @@
 #include <linux/err.h>
 #include <linux/scatterlist.h>
 #include <linux/list.h>
+#include <linux/mutex.h>
 #include <linux/dma-mapping.h>
 #include <linux/fs.h>
 #include <linux/dma-fence.h>
@@ -556,6 +557,11 @@ struct dma_buf_export_info {
 	struct dma_buf_export_info name = { .exp_name = KBUILD_MODNAME, \
 					 .owner = THIS_MODULE }
 
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+extern struct list_head dmabuf_debugfs_list;
+extern struct mutex dmabuf_debugfs_list_mutex;
+#endif
+
 /**
  * get_dma_buf - convenience wrapper for get_file.
  * @dmabuf:	[in]	pointer to dma_buf
-- 
2.49.0.604.gff1f9ca942-goog