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path: root/drivers/pps/pps.c
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Diffstat (limited to 'drivers/pps/pps.c')
-rw-r--r--drivers/pps/pps.c83
1 files changed, 57 insertions, 26 deletions
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 2420d5af0583..7173e3ad475d 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);
@@ -290,29 +295,21 @@ 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.
- * After idr_get_new() calling the new source will be freely available
- * into the kernel.
+ /*
+ * Get new ID for the new PPS source. After idr_alloc() calling
+ * the new source will be freely available into the kernel.
*/
- err = idr_get_new(&pps_idr, pps, &pps->id);
- mutex_unlock(&pps_idr_lock);
-
- if (err < 0)
- return err;
-
- pps->id &= MAX_IDR_MASK;
- if (pps->id >= PPS_MAX_SOURCES) {
- pr_err("%s: too many PPS sources in the system\n",
- pps->info.name);
- err = -EBUSY;
- goto free_idr;
+ err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
+ if (err < 0) {
+ if (err == -ENOSPC) {
+ pr_err("%s: too many PPS sources in the system\n",
+ pps->info.name);
+ err = -EBUSY;
+ }
+ goto out_unlock;
}
+ pps->id = err;
+ mutex_unlock(&pps_idr_lock);
devt = MKDEV(MAJOR(pps_devt), pps->id);
@@ -332,6 +329,7 @@ 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,
@@ -345,18 +343,51 @@ del_cdev:
free_idr:
mutex_lock(&pps_idr_lock);
idr_remove(&pps_idr, pps->id);
+out_unlock:
mutex_unlock(&pps_idr_lock);
-
return err;
}
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
*/