gigaset: avoid registering CAPI driver more than once

Registering/unregistering the Gigaset CAPI driver when a device is
connected/disconnected causes an Oops when disconnecting two Gigaset
devices in a row, because the same capi_driver structure gets
unregistered twice. Fix by making driver registration/unregistration
a separate operation (empty in the ISDN4Linux case) called when the
main module is loaded/unloaded.

Impact: bugfix
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Acked-by: Karsten Keil <keil@b1-systems.de>
CC: stable@kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 19 deletions

diff --git a/drivers/isdn/gigaset/capi.c b/drivers/isdn/gigaset/capi.c
index 6643d6533ccb..4a31962ddf71 100644
--- a/drivers/isdn/gigaset/capi.c
+++ b/drivers/isdn/gigaset/capi.c
@@ -2191,36 +2191,24 @@ static const struct file_operations gigaset_proc_fops = {
         .release        = single_release,
 };
 
-static struct capi_driver capi_driver_gigaset = {
-        .name           = "gigaset",
-        .revision       = "1.0",
-};
-
 /**
- * gigaset_isdn_register() - register to LL
+ * gigaset_isdn_regdev() - register device to LL
  * @cs:         device descriptor structure.
  * @isdnid:     device name.
  *
- * Called by main module to register the device with the LL.
- *
  * Return value: 1 for success, 0 for failure
  */
-int gigaset_isdn_register(struct cardstate *cs, const char *isdnid)
+int gigaset_isdn_regdev(struct cardstate *cs, const char *isdnid)
 {
         struct gigaset_capi_ctr *iif;
         int rc;
 
-        pr_info("Kernel CAPI interface\n");
-
         iif = kmalloc(sizeof(*iif), GFP_KERNEL);
         if (!iif) {
                 pr_err("%s: out of memory\n", __func__);
                 return 0;
         }
 
-        /* register driver with CAPI (ToDo: what for?) */
-        register_capi_driver(&capi_driver_gigaset);
-
         /* prepare controller structure */
         iif->ctr.owner         = THIS_MODULE;
         iif->ctr.driverdata    = cs;
@@ -2241,7 +2229,6 @@ int gigaset_isdn_register(struct cardstate *cs, const char *isdnid)
         rc = attach_capi_ctr(&iif->ctr);
         if (rc) {
                 pr_err("attach_capi_ctr failed (%d)\n", rc);
-                unregister_capi_driver(&capi_driver_gigaset);
                 kfree(iif);
                 return 0;
         }
@@ -2252,17 +2239,36 @@ int gigaset_isdn_register(struct cardstate *cs, const char *isdnid)
 }
 
 /**
- * gigaset_isdn_unregister() - unregister from LL
+ * gigaset_isdn_unregdev() - unregister device from LL
  * @cs:         device descriptor structure.
- *
- * Called by main module to unregister the device from the LL.
  */
-void gigaset_isdn_unregister(struct cardstate *cs)
+void gigaset_isdn_unregdev(struct cardstate *cs)
 {
         struct gigaset_capi_ctr *iif = cs->iif;
 
         detach_capi_ctr(&iif->ctr);
         kfree(iif);
         cs->iif = NULL;
+}
+
+static struct capi_driver capi_driver_gigaset = {
+        .name           = "gigaset",
+        .revision       = "1.0",
+};
+
+/**
+ * gigaset_isdn_regdrv() - register driver to LL
+ */
+void gigaset_isdn_regdrv(void)
+{
+        pr_info("Kernel CAPI interface\n");
+        register_capi_driver(&capi_driver_gigaset);
+}
+
+/**
+ * gigaset_isdn_unregdrv() - unregister driver from LL
+ */
+void gigaset_isdn_unregdrv(void)
+{
         unregister_capi_driver(&capi_driver_gigaset);
 }