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Date: Tue, 12 Feb 2013 02:02:42 -0500
From: George Spelvin <linux@...izon.com>
To: linux-serial@...r.kernel.org, peter@...leysoftware.com,
gregkh@...uxfoundation.org
Cc: linux-kernel@...r.kernel.org, giometti@...ux.it, linux@...izon.com
Subject: [PATCH v2 8/9] pps: Use a single cdev
One per device just seems wasteful, when we already manintain a
data structure to map minor numbers to devices, and we already have
a PPS_MAX_SOURCES #define.
This is also a more comprehensive fix to the use-after-free bug
that has already received a minimal patch.
---
drivers/pps/pps.c | 66 ++++++++++++++++++++++++----------------------
include/linux/pps_kernel.h | 1 -
2 files changed, 34 insertions(+), 33 deletions(-)
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 6437703..754b0b5 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -41,6 +41,8 @@
static dev_t pps_devt;
static struct class *pps_class;
+static struct cdev pps_cdev;
+
static DEFINE_MUTEX(pps_idr_lock);
static DEFINE_IDR(pps_idr);
@@ -244,17 +246,23 @@ static long pps_cdev_ioctl(struct file *file,
static int pps_cdev_open(struct inode *inode, struct file *file)
{
- struct pps_device *pps = container_of(inode->i_cdev,
- struct pps_device, cdev);
- file->private_data = pps;
- kobject_get(&pps->dev->kobj);
- return 0;
+ int err = -ENXIO;
+ struct pps_device *pps;
+
+ rcu_read_lock();
+ pps = idr_find(&pps_idr, iminor(inode));
+ if (pps) {
+ file->private_data = pps;
+ kobject_get(&pps->dev->kobj);
+ err = 0;
+ }
+ rcu_read_unlock();
+ return err;
}
static int pps_cdev_release(struct inode *inode, struct file *file)
{
- struct pps_device *pps = container_of(inode->i_cdev,
- struct pps_device, cdev);
+ struct pps_device *pps = file->private_data;
kobject_put(&pps->dev->kobj);
return 0;
}
@@ -277,8 +285,6 @@ static void pps_device_destruct(struct device *dev)
{
struct pps_device *pps = dev_get_drvdata(dev);
- cdev_del(&pps->cdev);
-
/* Now we can release the ID for re-use */
pr_debug("deallocating pps%d\n", pps->id);
mutex_lock(&pps_idr_lock);
@@ -295,17 +301,14 @@ int pps_register_cdev(struct pps_device *pps)
dev_t devt;
mutex_lock(&pps_idr_lock);
- /* Get new ID for the new PPS source */
- if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
- mutex_unlock(&pps_idr_lock);
- return -ENOMEM;
- }
-
- /* Now really allocate the PPS source.
+ /* Get new ID for the new PPS source.
* After idr_get_new() calling the new source will be freely available
* into the kernel.
*/
- err = idr_get_new(&pps_idr, pps, &pps->id);
+ if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0)
+ err = -ENOMEM;
+ else
+ err = idr_get_new(&pps_idr, pps, &pps->id);
mutex_unlock(&pps_idr_lock);
if (err < 0)
@@ -321,33 +324,21 @@ int pps_register_cdev(struct pps_device *pps)
devt = MKDEV(MAJOR(pps_devt), pps->id);
- cdev_init(&pps->cdev, &pps_cdev_fops);
- pps->cdev.owner = pps->info.owner;
-
- err = cdev_add(&pps->cdev, devt, 1);
- if (err) {
- pr_err("%s: failed to add char device %d:%d\n",
- pps->info.name, MAJOR(pps_devt), pps->id);
- goto free_idr;
- }
pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
"pps%d", pps->id);
if (IS_ERR(pps->dev)) {
err = PTR_ERR(pps->dev);
- goto del_cdev;
+ goto free_idr;
}
/* Override the release function with our own */
pps->dev->release = pps_device_destruct;
pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
- MAJOR(pps_devt), pps->id);
+ MAJOR(devt), MINOR(devt));
return 0;
-del_cdev:
- cdev_del(&pps->cdev);
-
free_idr:
mutex_lock(&pps_idr_lock);
idr_remove(&pps_idr, pps->id);
@@ -401,8 +392,9 @@ EXPORT_SYMBOL(pps_lookup_dev);
static void __exit pps_exit(void)
{
- class_destroy(pps_class);
+ cdev_del(&pps_cdev);
unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
+ class_destroy(pps_class);
}
static int __init pps_init(void)
@@ -422,12 +414,22 @@ static int __init pps_init(void)
goto remove_class;
}
+ cdev_init(&pps_cdev, &pps_cdev_fops);
+ pps_cdev.owner = THIS_MODULE;
+ err = cdev_add(&pps_cdev, pps_devt, PPS_MAX_SOURCES);
+ if (err < 0) {
+ pr_err("failed to register struct cdev\n");
+ goto remove_region;
+ }
+
pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
"<giometti@...ux.it>\n", PPS_VERSION);
return 0;
+remove_region:
+ unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
remove_class:
class_destroy(pps_class);
diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
index 7db3eb9..caca565 100644
--- a/include/linux/pps_kernel.h
+++ b/include/linux/pps_kernel.h
@@ -70,7 +70,6 @@ struct pps_device {
unsigned int id; /* PPS source unique ID */
void const *lookup_cookie; /* pps_lookup_dev only */
- struct cdev cdev;
struct device *dev;
struct fasync_struct *async_queue; /* fasync method */
spinlock_t lock;
--
1.8.1.3
--
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