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>

4 files changed, 53 insertions, 31 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);
 }
diff --git a/drivers/isdn/gigaset/common.c b/drivers/isdn/gigaset/common.c
index 85de3399a2f2..bdc01cb9f0ab 100644
--- a/drivers/isdn/gigaset/common.c
+++ b/drivers/isdn/gigaset/common.c
@@ -507,7 +507,7 @@ void gigaset_freecs(struct cardstate *cs)
         case 2: /* error in initcshw */
                 /* Deregister from LL */
                 make_invalid(cs, VALID_ID);
-                gigaset_isdn_unregister(cs);
+                gigaset_isdn_unregdev(cs);
 
                 /* fall through */
         case 1: /* error when registering to LL */
@@ -769,7 +769,7 @@ struct cardstate *gigaset_initcs(struct gigaset_driver *drv, int channels,
         cs->cmdbytes = 0;
 
         gig_dbg(DEBUG_INIT, "setting up iif");
-        if (!gigaset_isdn_register(cs, modulename)) {
+        if (!gigaset_isdn_regdev(cs, modulename)) {
                 pr_err("error registering ISDN device\n");
                 goto error;
         }
@@ -1205,11 +1205,13 @@ static int __init gigaset_init_module(void)
                 gigaset_debuglevel = DEBUG_DEFAULT;
 
         pr_info(DRIVER_DESC DRIVER_DESC_DEBUG "\n");
+        gigaset_isdn_regdrv();
         return 0;
 }
 
 static void __exit gigaset_exit_module(void)
 {
+        gigaset_isdn_unregdrv();
 }
 
 module_init(gigaset_init_module);
diff --git a/drivers/isdn/gigaset/gigaset.h b/drivers/isdn/gigaset/gigaset.h
index 1875ab80b335..cdd144ecdc5f 100644
--- a/drivers/isdn/gigaset/gigaset.h
+++ b/drivers/isdn/gigaset/gigaset.h
@@ -675,8 +675,10 @@ int gigaset_isowbuf_getbytes(struct isowbuf_t *iwb, int size);
  */
 
 /* Called from common.c for setting up/shutting down with the ISDN subsystem */
-int gigaset_isdn_register(struct cardstate *cs, const char *isdnid);
-void gigaset_isdn_unregister(struct cardstate *cs);
+void gigaset_isdn_regdrv(void);
+void gigaset_isdn_unregdrv(void);
+int gigaset_isdn_regdev(struct cardstate *cs, const char *isdnid);
+void gigaset_isdn_unregdev(struct cardstate *cs);
 
 /* Called from hardware module to indicate completion of an skb */
 void gigaset_skb_sent(struct bc_state *bcs, struct sk_buff *skb);
diff --git a/drivers/isdn/gigaset/i4l.c b/drivers/isdn/gigaset/i4l.c
index f0acb9dc9e33..c22e5ace8276 100644
--- a/drivers/isdn/gigaset/i4l.c
+++ b/drivers/isdn/gigaset/i4l.c
@@ -592,15 +592,13 @@ void gigaset_isdn_stop(struct cardstate *cs)
 }
 
 /**
- * gigaset_isdn_register() - register to LL
+ * gigaset_isdn_regdev() - register 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)
 {
         isdn_if *iif;
 
@@ -650,15 +648,29 @@ 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)
 {
         gig_dbg(DEBUG_CMD, "sending UNLOAD");
         gigaset_i4l_cmd(cs, ISDN_STAT_UNLOAD);
         kfree(cs->iif);
         cs->iif = NULL;
 }
+
+/**
+ * gigaset_isdn_regdrv() - register driver to LL
+ */
+void gigaset_isdn_regdrv(void)
+{
+        /* nothing to do */
+}
+
+/**
+ * gigaset_isdn_unregdrv() - unregister driver from LL
+ */
+void gigaset_isdn_unregdrv(void)
+{
+        /* nothing to do */
+}