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-rw-r--r--drivers/dma-buf/dma-buf.c98
1 files changed, 78 insertions, 20 deletions
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 0c48d41dd5eb..890ecac04dac 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -19,7 +19,9 @@
#include <linux/anon_inodes.h>
#include <linux/export.h>
#include <linux/debugfs.h>
+#include <linux/list.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/seq_file.h>
#include <linux/sync_file.h>
#include <linux/poll.h>
@@ -35,35 +37,91 @@
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);
+static DEFINE_MUTEX(dmabuf_list_mutex);
+static 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)
+
+/**
+ * dma_buf_iter_begin - begin iteration through global list of all DMA buffers
+ *
+ * Returns the first buffer in the global list of DMA-bufs that's not in the
+ * process of being destroyed. Increments that buffer's reference count to
+ * prevent buffer destruction. Callers must release the reference, either by
+ * continuing iteration with dma_buf_iter_next(), or with dma_buf_put().
+ *
+ * Return:
+ * * First buffer from global list, with refcount elevated
+ * * NULL if no active buffers are present
+ */
+struct dma_buf *dma_buf_iter_begin(void)
{
+ struct dma_buf *ret = NULL, *dmabuf;
+
+ /*
+ * The list mutex does not protect a dmabuf's refcount, so it can be
+ * zeroed while we are iterating. We cannot call get_dma_buf() since the
+ * caller may not already own a reference to the buffer.
+ */
+ mutex_lock(&dmabuf_list_mutex);
+ list_for_each_entry(dmabuf, &dmabuf_list, list_node) {
+ if (file_ref_get(&dmabuf->file->f_ref)) {
+ ret = dmabuf;
+ break;
+ }
+ }
+ mutex_unlock(&dmabuf_list_mutex);
+ return ret;
}
-static void __dma_buf_debugfs_list_del(struct dma_buf *dmabuf)
+/**
+ * dma_buf_iter_next - continue iteration through global list of all DMA buffers
+ * @dmabuf: [in] pointer to dma_buf
+ *
+ * Decrements the reference count on the provided buffer. Returns the next
+ * buffer from the remainder of the global list of DMA-bufs with its reference
+ * count incremented. Callers must release the reference, either by continuing
+ * iteration with dma_buf_iter_next(), or with dma_buf_put().
+ *
+ * Return:
+ * * Next buffer from global list, with refcount elevated
+ * * NULL if no additional active buffers are present
+ */
+struct dma_buf *dma_buf_iter_next(struct dma_buf *dmabuf)
{
+ struct dma_buf *ret = NULL;
+
+ /*
+ * The list mutex does not protect a dmabuf's refcount, so it can be
+ * zeroed while we are iterating. We cannot call get_dma_buf() since the
+ * caller may not already own a reference to the buffer.
+ */
+ mutex_lock(&dmabuf_list_mutex);
+ dma_buf_put(dmabuf);
+ list_for_each_entry_continue(dmabuf, &dmabuf_list, list_node) {
+ if (file_ref_get(&dmabuf->file->f_ref)) {
+ ret = dmabuf;
+ break;
+ }
+ }
+ mutex_unlock(&dmabuf_list_mutex);
+ return ret;
}
-#endif
static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
{
@@ -115,7 +173,7 @@ 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;
}
@@ -685,7 +743,7 @@ 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;
@@ -1563,7 +1621,7 @@ 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;
@@ -1572,7 +1630,7 @@ 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)
@@ -1609,11 +1667,11 @@ 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;
}