1 files changed, 37 insertions, 6 deletions

diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 06b448285eb5..7b2728b8f1b7 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -250,6 +250,7 @@ static int ppp_connect_channel(struct channel *pch, int unit);
 static int ppp_disconnect_channel(struct channel *pch);
 static void ppp_destroy_channel(struct channel *pch);
 static int unit_get(struct idr *p, void *ptr);
+static int unit_set(struct idr *p, void *ptr, int n);
 static void unit_put(struct idr *p, int n);
 static void *unit_find(struct idr *p, int n);
 
@@ -2432,11 +2433,18 @@ ppp_create_interface(int unit, int *retp)
         } else {
                 if (unit_find(&ppp_units_idr, unit))
                         goto out2; /* unit already exists */
-                else {
-                        /* darn, someone is cheating us? */
-                        *retp = -EINVAL;
+                /*
+                 * if caller need a specified unit number
+                 * lets try to satisfy him, otherwise --
+                 * he should better ask us for new unit number
+                 *
+                 * NOTE: yes I know that returning EEXIST it's not
+                 * fair but at least pppd will ask us to allocate
+                 * new unit in this case so user is happy :)
+                 */
+                unit = unit_set(&ppp_units_idr, ppp, unit);
+                if (unit < 0)
                         goto out2;
-                }
         }
 
         /* Initialize the new ppp unit */
@@ -2677,14 +2685,37 @@ static void __exit ppp_cleanup(void)
  * by holding all_ppp_mutex
  */
 
+/* associate pointer with specified number */
+static int unit_set(struct idr *p, void *ptr, int n)
+{
+        int unit, err;
+
+again:
+        if (!idr_pre_get(p, GFP_KERNEL)) {
+                printk(KERN_ERR "PPP: No free memory for idr\n");
+                return -ENOMEM;
+        }
+
+        err = idr_get_new_above(p, ptr, n, &unit);
+        if (err == -EAGAIN)
+                goto again;
+
+        if (unit != n) {
+                idr_remove(p, unit);
+                return -EINVAL;
+        }
+
+        return unit;
+}
+
 /* get new free unit number and associate pointer with it */
 static int unit_get(struct idr *p, void *ptr)
 {
         int unit, err;
 
 again:
-        if (idr_pre_get(p, GFP_KERNEL) == 0) {
-                printk(KERN_ERR "Out of memory expanding drawable idr\n");
+        if (!idr_pre_get(p, GFP_KERNEL)) {
+                printk(KERN_ERR "PPP: No free memory for idr\n");
                 return -ENOMEM;
         }