linux-kernel - [PATCH 01/10] devtmpfs: Convert dirlock to a mutex

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Date:	Wed, 23 Dec 2009 11:52:34 -0800
From:	Greg Kroah-Hartman <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Kay Sievers <kay.sievers@...y.org>, stable <stable@...nel.org>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [PATCH 01/10] devtmpfs: Convert dirlock to a mutex

From: Thomas Gleixner <tglx@...utronix.de>

devtmpfs has a rw_lock dirlock which serializes delete_path and
create_path.

This code was obviously never tested with the usual set of debugging
facilities enabled. In the dirlock held sections the code calls:

 - vfs functions which take mutexes
 - kmalloc(, GFP_KERNEL)

In both code pathes the might sleep warning triggers and spams dmesg.

Convert the rw_lock to a mutex. There is no reason why this needs to
be a rwlock.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Kay Sievers <kay.sievers@...y.org>
Cc: stable <stable@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 drivers/base/devtmpfs.c |   12 +++++-------
 1 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 50375bb..278371c 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -32,7 +32,7 @@ static int dev_mount = 1;
 static int dev_mount;
 #endif
 
-static rwlock_t dirlock;
+static DEFINE_MUTEX(dirlock);
 
 static int __init mount_param(char *str)
 {
@@ -93,7 +93,7 @@ static int create_path(const char *nodepath)
 {
 	int err;
 
-	read_lock(&dirlock);
+	mutex_lock(&dirlock);
 	err = dev_mkdir(nodepath, 0755);
 	if (err == -ENOENT) {
 		char *path;
@@ -117,7 +117,7 @@ static int create_path(const char *nodepath)
 		}
 		kfree(path);
 	}
-	read_unlock(&dirlock);
+	mutex_unlock(&dirlock);
 	return err;
 }
 
@@ -229,7 +229,7 @@ static int delete_path(const char *nodepath)
 	if (!path)
 		return -ENOMEM;
 
-	write_lock(&dirlock);
+	mutex_lock(&dirlock);
 	for (;;) {
 		char *base;
 
@@ -241,7 +241,7 @@ static int delete_path(const char *nodepath)
 		if (err)
 			break;
 	}
-	write_unlock(&dirlock);
+	mutex_unlock(&dirlock);
 
 	kfree(path);
 	return err;
@@ -352,8 +352,6 @@ int __init devtmpfs_init(void)
 	int err;
 	struct vfsmount *mnt;
 
-	rwlock_init(&dirlock);
-
 	err = register_filesystem(&dev_fs_type);
 	if (err) {
 		printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
-- 
1.6.5.7

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