[PATCH v4] xen/debugfs: Check debugfs initialization before using it

[Ethan Zhao <ethan.kernel@gmail.com>]

Should check debugfs initialization with debugfs_initialized() before using it,
Because if it isn't initialized, the return value of fake debugfs_create_dir() etc
functions would be ERR_PTR(-ENODEV), checking with NULL will not work.

V2: change author name to normative format.
V3: add warning message about debugfs not configured or disabled.
V4: make the warning clear.

Signed-off-by: Ethan Zhao <ethan.kernel@gmail.com>
---
 arch/x86/xen/debugfs.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/xen/debugfs.c b/arch/x86/xen/debugfs.c
index c8377fb..7f3804c 100644
--- a/arch/x86/xen/debugfs.c
+++ b/arch/x86/xen/debugfs.c
@@ -9,12 +9,19 @@ static struct dentry *d_xen_debug;
 
 struct dentry * __init xen_init_debugfs(void)
 {
+	if (!debugfs_initialized()) {
+		d_xen_debug = NULL;
+		pr_warning("Debugfs is not configured or not enabled\n");
+		goto nodebugfs;
+	}
+
 	if (!d_xen_debug) {
 		d_xen_debug = debugfs_create_dir("xen", NULL);
 
 		if (!d_xen_debug)
 			pr_warning("Could not create 'xen' debugfs directory\n");
 	}
+nodebugfs:
 
 	return d_xen_debug;
 }
-- 
1.8.3.4 (Apple Git-47)