Global variable bcache_debug is firstly initialized in bch_debug_init(),
and destroyed in bch_debug_exit(). bch_debug_init() is called in
bcache_init() with many other functions, if one of the previous calling
onces failed, bcache_exit() will be called in the failure path.

The problem is, if bcache_init() fails before bch_debug_init() is called,
then in bcache_exit() when bch_debug_exit() is called to destroy global
variable bcache_debug, at this moment bcache_debug is unndefined, then the
test of "if (!IS_ERR_OR_NULL(bcache_debug))" might be buggy.

This patch initializes global varabile bcache_debug to be NULL, to make
the failure code path to be predictable.

Signed-off-by: Coly Li <redacted>
---
 drivers/md/bcache/debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
index 57f8f5aeee55..24b0eb65ddec 100644
--- a/drivers/md/bcache/debug.c
+++ b/drivers/md/bcache/debug.c

@@ -17,7 +17,7 @@
 #include <linux/random.h>
 #include <linux/seq_file.h>
 
-struct dentry *bcache_debug;
+struct dentry *bcache_debug = NULL;
 
 #ifdef CONFIG_BCACHE_DEBUG
 

-- 
2.17.1