btrfs: Fix suspicious RCU usage warning in btrfs_debug_in_rcu

t-msn · kdave · commit b6fdfbff0789 · 2018-08-24T14:09:43.000+02:00
Commit 672d599 ("btrfs: Use wrapper macro for rcu string to remove duplicate code") replaces some open coded RCU string handling with macro. It turns out that btrfs_debug_in_rcu() is used for the first time and the macro lacks lock/unlock of RCU string for non-debug case (i.e. when the message is not printed), leading to suspicious RCU usage warning when CONFIG_PROVE_RCU is on. Fix this by adding a wrapper to call lock/unlock for the non-debug case too. Fixes: 672d599 ("btrfs: Use wrapper macro for rcu string to remove duplicate code") Reported-by: David Howells <dhowells@redhat.com> Tested-by: David Howells <dhowells@redhat.com> Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
@@ -3390,9 +3390,9 @@ do {									\
 #define btrfs_debug(fs_info, fmt, args...) \
 	btrfs_no_printk(fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_in_rcu(fs_info, fmt, args...) \
-	btrfs_no_printk(fs_info, KERN_DEBUG fmt, ##args)
+	btrfs_no_printk_in_rcu(fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_rl_in_rcu(fs_info, fmt, args...) \
-	btrfs_no_printk(fs_info, KERN_DEBUG fmt, ##args)
+	btrfs_no_printk_in_rcu(fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_rl(fs_info, fmt, args...) \
 	btrfs_no_printk(fs_info, KERN_DEBUG fmt, ##args)
 #endif
@@ -3404,6 +3404,13 @@ do {							\
 	rcu_read_unlock();				\
 } while (0)
 
+#define btrfs_no_printk_in_rcu(fs_info, fmt, args...)	\
+do {							\
+	rcu_read_lock();				\
+	btrfs_no_printk(fs_info, fmt, ##args);		\
+	rcu_read_unlock();				\
+} while (0)
+
 #define btrfs_printk_ratelimited(fs_info, fmt, args...)		\
 do {								\
 	static DEFINE_RATELIMIT_STATE(_rs,			\
