pps: move idr stuff to pps.c

Since now idr is only used to manage char device id's and not used in
kernel API anymore it should be moved to pps.c.  This also makes it
possible to release id only at actual device freeing so nobody can
register a pps device with the same id while our device is not freed yet.

Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 49 insertions, 1 deletions

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 9f7c2e858dd0..79b445578132 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -30,6 +30,7 @@
 #include <linux/cdev.h>
 #include <linux/poll.h>
 #include <linux/pps_kernel.h>
+#include <linux/slab.h>
 
 /*
  * Local variables
@@ -38,6 +39,9 @@
 static dev_t pps_devt;
 static struct class *pps_class;
 
+static DEFINE_SPINLOCK(pps_idr_lock);
+static DEFINE_IDR(pps_idr);
+
 /*
  * Char device methods
  */
@@ -229,11 +233,48 @@ static const struct file_operations pps_cdev_fops = {
         .release        = pps_cdev_release,
 };
 
+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 */
+        spin_lock_irq(&pps_idr_lock);
+        idr_remove(&pps_idr, pps->id);
+        spin_unlock_irq(&pps_idr_lock);
+
+        kfree(dev);
+        kfree(pps);
+}
+
 int pps_register_cdev(struct pps_device *pps)
 {
         int err;
         dev_t devt;
 
+        /* Get new ID for the new PPS source */
+        if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0)
+                return -ENOMEM;
+
+        /* Now really allocate the PPS source.
+         * After idr_get_new() calling the new source will be freely available
+         * into the kernel.
+         */
+        spin_lock_irq(&pps_idr_lock);
+        err = idr_get_new(&pps_idr, pps, &pps->id);
+        spin_unlock_irq(&pps_idr_lock);
+
+        if (err < 0)
+                return err;
+
+        pps->id &= MAX_ID_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;
+        }
+
         devt = MKDEV(MAJOR(pps_devt), pps->id);
 
         cdev_init(&pps->cdev, &pps_cdev_fops);
@@ -243,13 +284,15 @@ int pps_register_cdev(struct pps_device *pps)
         if (err) {
                 pr_err("%s: failed to add char device %d:%d\n",
                                 pps->info.name, MAJOR(pps_devt), pps->id);
-                return err;
+                goto free_idr;
         }
         pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
                                                         "pps%d", pps->id);
         if (IS_ERR(pps->dev))
                 goto del_cdev;
 
+        pps->dev->release = pps_device_destruct;
+
         pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
                         MAJOR(pps_devt), pps->id);
 
@@ -258,6 +301,11 @@ int pps_register_cdev(struct pps_device *pps)
 del_cdev:
         cdev_del(&pps->cdev);
 
+free_idr:
+        spin_lock_irq(&pps_idr_lock);
+        idr_remove(&pps_idr, pps->id);
+        spin_unlock_irq(&pps_idr_lock);
+
         return err;
 }