diff options
Diffstat (limited to 'drivers/pps/pps.c')
| -rw-r--r-- | drivers/pps/pps.c | 47 |
1 files changed, 43 insertions, 4 deletions
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c index 2420d5af058..6437703eb10 100644 --- a/drivers/pps/pps.c +++ b/drivers/pps/pps.c @@ -247,12 +247,15 @@ 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; } static int pps_cdev_release(struct inode *inode, struct file *file) { + struct pps_device *pps = container_of(inode->i_cdev, + struct pps_device, cdev); + kobject_put(&pps->dev->kobj); return 0; } @@ -274,8 +277,10 @@ static void pps_device_destruct(struct device *dev) { struct pps_device *pps = dev_get_drvdata(dev); - /* release id here to protect others from using it while it's - * still in use */ + 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); idr_remove(&pps_idr, pps->id); mutex_unlock(&pps_idr_lock); @@ -332,6 +337,7 @@ int pps_register_cdev(struct pps_device *pps) goto del_cdev; } + /* 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, @@ -352,11 +358,44 @@ free_idr: void pps_unregister_cdev(struct pps_device *pps) { + pr_debug("unregistering pps%d\n", pps->id); + pps->lookup_cookie = NULL; device_destroy(pps_class, pps->dev->devt); - cdev_del(&pps->cdev); } /* + * Look up a pps device by magic cookie. + * The cookie is usually a pointer to some enclosing device, but this + * code doesn't care; you should never be dereferencing it. + * + * This is a bit of a kludge that is currently used only by the PPS + * serial line discipline. It may need to be tweaked when a second user + * is found. + * + * There is no function interface for setting the lookup_cookie field. + * It's initialized to NULL when the pps device is created, and if a + * client wants to use it, just fill it in afterward. + * + * The cookie is automatically set to NULL in pps_unregister_source() + * so that it will not be used again, even if the pps device cannot + * be removed from the idr due to pending references holding the minor + * number in use. + */ +struct pps_device *pps_lookup_dev(void const *cookie) +{ + struct pps_device *pps; + unsigned id; + + rcu_read_lock(); + idr_for_each_entry(&pps_idr, pps, id) + if (cookie == pps->lookup_cookie) + break; + rcu_read_unlock(); + return pps; +} +EXPORT_SYMBOL(pps_lookup_dev); + +/* * Module stuff */ |