debugfs: make sure we can remove u32_array files cleanly

debugfs_create_u32_array() allocates a small structure to wrap
the data and size information about the array. If users ever
try to remove the file this leads to a leak since nothing ever
frees this wrapper.

That said there are no upstream users of debugfs_create_u32_array()
that'd remove a u32 array file (we only have one u32 array user in
CMA), so there is no real bug here.

Make callers pass a wrapper they allocated. This way the lifetime
management of the wrapper is on the caller, and we can avoid the
potential leak in debugfs.

CC: Chucheng Luo <luochucheng@vivo.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index 63cb3606dea7..851dd1f9a8a5 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -38,6 +38,11 @@ struct debugfs_regset32 {
 	struct device *dev;	/* Optional device for Runtime PM */
 };
 
+struct debugfs_u32_array {
+	u32 *array;
+	u32 n_elements;
+};
+
 extern struct dentry *arch_debugfs_dir;
 
 #define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt)		\
@@ -136,7 +141,8 @@ void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
 			  int nregs, void __iomem *base, char *prefix);
 
 void debugfs_create_u32_array(const char *name, umode_t mode,
-			      struct dentry *parent, u32 *array, u32 elements);
+			      struct dentry *parent,
+			      struct debugfs_u32_array *array);
 
 struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,
 					   struct dentry *parent,
@@ -316,8 +322,8 @@ static inline bool debugfs_initialized(void)
 }
 
 static inline void debugfs_create_u32_array(const char *name, umode_t mode,
-					    struct dentry *parent, u32 *array,
-					    u32 elements)
+					    struct dentry *parent,
+					    struct debugfs_u32_array *array)
 {
 }