[media] lirc_dev: rework storage for cdev data

Fixes an oops when an lirc driver that doesn't provide its own fops is
unplugged while the lirc cdev is open. Tested with lirc_igorplugusb,
with a special thanks to Timo Boettcher for providing the test hardware.

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 23 insertions, 17 deletions

diff --git a/drivers/media/IR/lirc_dev.c b/drivers/media/IR/lirc_dev.c
index 8fdb7e11a138..3ef15625fa84 100644
--- a/drivers/media/IR/lirc_dev.c
+++ b/drivers/media/IR/lirc_dev.c
@@ -58,13 +58,12 @@ struct irctl {
 
         struct task_struct *task;
         long jiffies_to_wait;
-
-        struct cdev cdev;
 };
 
 static DEFINE_MUTEX(lirc_dev_lock);
 
 static struct irctl *irctls[MAX_IRCTL_DEVICES];
+static struct cdev cdevs[MAX_IRCTL_DEVICES];
 
 /* Only used for sysfs but defined to void otherwise */
 static struct class *lirc_class;
@@ -170,19 +169,20 @@ static int lirc_cdev_add(struct irctl *ir)
 {
         int retval;
         struct lirc_driver *d = &ir->d;
+        struct cdev *cdev = &cdevs[d->minor];
 
         if (d->fops) {
-                cdev_init(&ir->cdev, d->fops);
-                ir->cdev.owner = d->owner;
+                cdev_init(cdev, d->fops);
+                cdev->owner = d->owner;
         } else {
-                cdev_init(&ir->cdev, &lirc_dev_fops);
-                ir->cdev.owner = THIS_MODULE;
+                cdev_init(cdev, &lirc_dev_fops);
+                cdev->owner = THIS_MODULE;
         }
-        kobject_set_name(&ir->cdev.kobj, "lirc%d", d->minor);
+        kobject_set_name(&cdev->kobj, "lirc%d", d->minor);
 
-        retval = cdev_add(&ir->cdev, MKDEV(MAJOR(lirc_base_dev), d->minor), 1);
+        retval = cdev_add(cdev, MKDEV(MAJOR(lirc_base_dev), d->minor), 1);
         if (retval)
-                kobject_put(&ir->cdev.kobj);
+                kobject_put(&cdev->kobj);
 
         return retval;
 }
@@ -363,6 +363,7 @@ EXPORT_SYMBOL(lirc_register_driver);
 int lirc_unregister_driver(int minor)
 {
         struct irctl *ir;
+        struct cdev *cdev;
 
         if (minor < 0 || minor >= MAX_IRCTL_DEVICES) {
                 printk(KERN_ERR "lirc_dev: %s: minor (%d) must be between "
@@ -377,6 +378,8 @@ int lirc_unregister_driver(int minor)
                 return -ENOENT;
         }
 
+        cdev = &cdevs[minor];
+
         mutex_lock(&lirc_dev_lock);
 
         if (ir->d.minor != minor) {
@@ -400,11 +403,11 @@ int lirc_unregister_driver(int minor)
                 wake_up_interruptible(&ir->buf->wait_poll);
                 mutex_lock(&ir->irctl_lock);
                 ir->d.set_use_dec(ir->d.data);
-                module_put(ir->cdev.owner);
+                module_put(cdev->owner);
                 mutex_unlock(&ir->irctl_lock);
         } else {
                 lirc_irctl_cleanup(ir);
-                cdev_del(&ir->cdev);
+                cdev_del(cdev);
                 kfree(ir);
                 irctls[minor] = NULL;
         }
@@ -418,6 +421,7 @@ EXPORT_SYMBOL(lirc_unregister_driver);
 int lirc_dev_fop_open(struct inode *inode, struct file *file)
 {
         struct irctl *ir;
+        struct cdev *cdev;
         int retval = 0;
 
         if (iminor(inode) >= MAX_IRCTL_DEVICES) {
@@ -447,13 +451,14 @@ int lirc_dev_fop_open(struct inode *inode, struct file *file)
                 goto error;
         }
 
-        if (try_module_get(ir->cdev.owner)) {
-                ++ir->open;
+        cdev = &cdevs[iminor(inode)];
+        if (try_module_get(cdev->owner)) {
+                ir->open++;
                 retval = ir->d.set_use_inc(ir->d.data);
 
                 if (retval) {
-                        module_put(ir->cdev.owner);
-                        --ir->open;
+                        module_put(cdev->owner);
+                        ir->open--;
                 } else {
                         lirc_buffer_clear(ir->buf);
                 }
@@ -475,6 +480,7 @@ EXPORT_SYMBOL(lirc_dev_fop_open);
 int lirc_dev_fop_close(struct inode *inode, struct file *file)
 {
         struct irctl *ir = irctls[iminor(inode)];
+        struct cdev *cdev = &cdevs[iminor(inode)];
 
         if (!ir) {
                 printk(KERN_ERR "%s: called with invalid irctl\n", __func__);
@@ -488,10 +494,10 @@ int lirc_dev_fop_close(struct inode *inode, struct file *file)
         ir->open--;
         if (ir->attached) {
                 ir->d.set_use_dec(ir->d.data);
-                module_put(ir->cdev.owner);
+                module_put(cdev->owner);
         } else {
                 lirc_irctl_cleanup(ir);
-                cdev_del(&ir->cdev);
+                cdev_del(cdev);
                 irctls[ir->d.minor] = NULL;
                 kfree(ir);
         }