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, 3 insertions, 0 deletions

diff --git a/mm/cma.h b/mm/cma.h
index 33c0b517733c..6698fa63279b 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -2,6 +2,8 @@
 #ifndef __MM_CMA_H__
 #define __MM_CMA_H__
 
+#include <linux/debugfs.h>
+
 struct cma {
 	unsigned long   base_pfn;
 	unsigned long   count;
@@ -11,6 +13,7 @@ struct cma {
 #ifdef CONFIG_CMA_DEBUGFS
 	struct hlist_head mem_head;
 	spinlock_t mem_head_lock;
+	struct debugfs_u32_array dfs_bitmap;
 #endif
 	const char *name;
 };