ipmi: make sure drivers were registered before unregistering them

The ipmi code will never register a PCI or Open Firmware driver if a
hardcoded device is provided by the user by providing device addresses via
the module parameters.  This can cause us to attempt to unregister a
driver that was never registered, resulting in an oops.  Keep track of
registration in order to avoid this.

Fixes a post-2.6.34 regression.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/ipmi/ipmi_si_intf.c

@@ -302,6 +302,12 @@ struct smi_info {
 
 static int force_kipmid[SI_MAX_PARMS];
 static int num_force_kipmid;
+#ifdef CONFIG_PCI
+static int pci_registered;
+#endif
+#ifdef CONFIG_PPC_OF
+static int of_registered;
+#endif
 
 static unsigned int kipmid_max_busy_us[SI_MAX_PARMS];
 static int num_max_busy_us;
@@ -3314,6 +3320,8 @@ static __devinit int init_ipmi_si(void)
 	rv = pci_register_driver(&ipmi_pci_driver);
 	if (rv)
 		printk(KERN_ERR PFX "Unable to register PCI driver: %d\n", rv);
+	else
+		pci_registered = 1;
 #endif
 
 #ifdef CONFIG_ACPI
@@ -3330,6 +3338,7 @@ static __devinit int init_ipmi_si(void)
 
 #ifdef CONFIG_PPC_OF
 	of_register_platform_driver(&ipmi_of_platform_driver);
+	of_registered = 1;
 #endif
 
 	/* We prefer devices with interrupts, but in the case of a machine
@@ -3383,10 +3392,12 @@ static __devinit int init_ipmi_si(void)
 	if (unload_when_empty && list_empty(&smi_infos)) {
 		mutex_unlock(&smi_infos_lock);
 #ifdef CONFIG_PCI
+		if (pci_registered)
 			pci_unregister_driver(&ipmi_pci_driver);
 #endif
 
 #ifdef CONFIG_PPC_OF
+		if (of_registered)
 			of_unregister_platform_driver(&ipmi_of_platform_driver);
 #endif
 		driver_unregister(&ipmi_driver.driver);
@@ -3478,6 +3489,7 @@ static __exit void cleanup_ipmi_si(void)
 		return;
 
 #ifdef CONFIG_PCI
+	if (pci_registered)
 		pci_unregister_driver(&ipmi_pci_driver);
 #endif
 #ifdef CONFIG_ACPI
@@ -3485,6 +3497,7 @@ static __exit void cleanup_ipmi_si(void)
 #endif
 
 #ifdef CONFIG_PPC_OF
+	if (of_registered)
 		of_unregister_platform_driver(&ipmi_of_platform_driver);
 #endif