linux-kernel - [PATCH] xen/debugfs: Check debugfs initialization before using it

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Date:	Mon,  9 Dec 2013 18:04:03 +0800
From:	Ethan Zhao <ethan.kernel@...il.com>
To:	gregkh@...uxfoundation.org, konrad.wilk@...cle.com,
	raghavendra.kt@...ux.vnet.ibm.com
Cc:	linux-kernel@...r.kernel.org, "Ethan Zhao" <ethan.kernel@...il.com>
Subject: [PATCH] xen/debugfs: Check debugfs initialization before using it

From: "Ethan Zhao" <ethan.kernel@...il.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.

V3: Add warning message about debugfs not configured or disabled. 

Signed-off-by: Ethan Zhao <ethan.kernel@...il.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..033a5dd 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 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)

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