[PATCH v2 1/6] dma-buf: Rename and expose debugfs symbols

["T.J. Mercier" <tjmercier@google.com>]

Expose the debugfs list and mutex so they are usable for the creation of
a BPF iterator for dmabufs without the need for CONFIG_DEBUG_FS. Rename
the symbols so it's clear debugfs is not required, and that the list
contains dmabufs and not some other type.

Signed-off-by: T.J. Mercier <tjmercier@google.com>
---
v2: Make the DMA buffer list independent of CONFIG_DEBUG_FS per Christian König
 drivers/dma-buf/dma-buf.c | 40 +++++++++++++++------------------------
 include/linux/dma-buf.h   |  6 ++++--
 2 files changed, 19 insertions(+), 27 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 5baa83b85515..7260bdd77c75 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -35,35 +35,25 @@
 
 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_list_mutex);
+LIST_HEAD(dmabuf_list);
 
-static void __dma_buf_debugfs_list_add(struct dma_buf *dmabuf)
+static void __dma_buf_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_list_mutex);
+	list_add(&dmabuf->list_node, &dmabuf_list);
+	mutex_unlock(&dmabuf_list_mutex);
 }
 
-static void __dma_buf_debugfs_list_del(struct dma_buf *dmabuf)
+static void __dma_buf_list_del(struct dma_buf *dmabuf)
 {
 	if (!dmabuf)
 		return;
 
-	mutex_lock(&debugfs_list_mutex);
+	mutex_lock(&dmabuf_list_mutex);
 	list_del(&dmabuf->list_node);
-	mutex_unlock(&debugfs_list_mutex);
+	mutex_unlock(&dmabuf_list_mutex);
 }
-#else
-static void __dma_buf_debugfs_list_add(struct dma_buf *dmabuf)
-{
-}
-
-static void __dma_buf_debugfs_list_del(struct dma_buf *dmabuf)
-{
-}
-#endif
 
 static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
 {
@@ -115,7 +105,7 @@ static int dma_buf_file_release(struct inode *inode, struct file *file)
 	if (!is_dma_buf_file(file))
 		return -EINVAL;
 
-	__dma_buf_debugfs_list_del(file->private_data);
+	__dma_buf_list_del(file->private_data);
 
 	return 0;
 }
@@ -689,7 +679,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 	file->f_path.dentry->d_fsdata = dmabuf;
 	dmabuf->file = file;
 
-	__dma_buf_debugfs_list_add(dmabuf);
+	__dma_buf_list_add(dmabuf);
 
 	return dmabuf;
 
@@ -1630,7 +1620,7 @@ 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_list_mutex);
 
 	if (ret)
 		return ret;
@@ -1639,7 +1629,7 @@ 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_list, list_node) {
 
 		ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);
 		if (ret)
@@ -1676,11 +1666,11 @@ 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_list_mutex);
 	return 0;
 
 error_unlock:
-	mutex_unlock(&debugfs_list_mutex);
+	mutex_unlock(&dmabuf_list_mutex);
 	return ret;
 }
 
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 36216d28d8bd..ebcd208272bf 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>
@@ -370,10 +371,8 @@ struct dma_buf {
 	 */
 	struct module *owner;
 
-#if IS_ENABLED(CONFIG_DEBUG_FS)
 	/** @list_node: node for dma_buf accounting and debugging. */
 	struct list_head list_node;
-#endif
 
 	/** @priv: exporter specific private data for this buffer object. */
 	void *priv;
@@ -556,6 +555,9 @@ struct dma_buf_export_info {
 	struct dma_buf_export_info name = { .exp_name = KBUILD_MODNAME, \
 					 .owner = THIS_MODULE }
 
+extern struct list_head dmabuf_list;
+extern struct mutex dmabuf_list_mutex;
+
 /**
  * get_dma_buf - convenience wrapper for get_file.
  * @dmabuf:	[in]	pointer to dma_buf
-- 
2.49.0.906.g1f30a19c02-goog