linux-kernel - [PATCH 2/2] hwrng: Avoid manual device_create

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Date:	Mon,  2 Feb 2015 15:44:55 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Arnd Bergmann <arnd@...db.de>, Matt Mackall <mpm@...enic.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] hwrng: Avoid manual device_create_file() calls

Use the new group field of struct miscdevice for managing the sysfs
entries instead of manually adding/removing via device_create_file()
and device_remove_file().  This simplifies the code a lot and fixes
the possible races.

Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 drivers/char/hw_random/core.c | 34 +++++++++++-----------------------
 1 file changed, 11 insertions(+), 23 deletions(-)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 1500cfd799a7..a79ba8ad8ff5 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -218,11 +218,14 @@ static const struct file_operations rng_chrdev_ops = {
 	.llseek		= noop_llseek,
 };
 
+static const struct attribute_group *rng_dev_groups[];
+
 static struct miscdevice rng_miscdev = {
 	.minor		= RNG_MISCDEV_MINOR,
 	.name		= RNG_MODULE_NAME,
 	.nodename	= "hwrng",
 	.fops		= &rng_chrdev_ops,
+	.groups		= rng_dev_groups,
 };
 
 
@@ -304,37 +307,22 @@ static DEVICE_ATTR(rng_available, S_IRUGO,
 		   hwrng_attr_available_show,
 		   NULL);
 
+static struct attribute *rng_dev_attrs[] = {
+	&dev_attr_rng_current.attr,
+	&dev_attr_rng_available.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(rng_dev);
 
 static void unregister_miscdev(void)
 {
-	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
-	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
 	misc_deregister(&rng_miscdev);
 }
 
 static int register_miscdev(void)
 {
-	int err;
-
-	err = misc_register(&rng_miscdev);
-	if (err)
-		goto out;
-	err = device_create_file(rng_miscdev.this_device,
-				 &dev_attr_rng_current);
-	if (err)
-		goto err_misc_dereg;
-	err = device_create_file(rng_miscdev.this_device,
-				 &dev_attr_rng_available);
-	if (err)
-		goto err_remove_current;
-out:
-	return err;
-
-err_remove_current:
-	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
-err_misc_dereg:
-	misc_deregister(&rng_miscdev);
-	goto out;
+	return misc_register(&rng_miscdev);
 }
 
 static int hwrng_fillfn(void *unused)
-- 
2.2.2

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