#include <linux/ioc4.h>
 #include <linux/mmtimer.h>
 #include <linux/rtc.h>
-#include <linux/rwsem.h>
+#include <linux/mutex.h>
 #include <asm/sn/addrs.h>
 #include <asm/sn/clksupport.h>
 #include <asm/sn/shub_mmr.h>
  * Submodule management *
  ************************/
 
-static LIST_HEAD(ioc4_devices);
-static DECLARE_RWSEM(ioc4_devices_rwsem);
+static DEFINE_MUTEX(ioc4_mutex);
 
+static LIST_HEAD(ioc4_devices);
 static LIST_HEAD(ioc4_submodules);
-static DECLARE_RWSEM(ioc4_submodules_rwsem);
 
 /* Register an IOC4 submodule */
 int
 {
        struct ioc4_driver_data *idd;
 
-       down_write(&ioc4_submodules_rwsem);
+       mutex_lock(&ioc4_mutex);
        list_add(&is->is_list, &ioc4_submodules);
-       up_write(&ioc4_submodules_rwsem);
 
        /* Initialize submodule for each IOC4 */
        if (!is->is_probe)
-               return 0;
+               goto out;
 
-       down_read(&ioc4_devices_rwsem);
        list_for_each_entry(idd, &ioc4_devices, idd_list) {
                if (is->is_probe(idd)) {
                        printk(KERN_WARNING
                               pci_name(idd->idd_pdev));
                }
        }
-       up_read(&ioc4_devices_rwsem);
-
+ out:
+       mutex_unlock(&ioc4_mutex);
        return 0;
 }
 
 {
        struct ioc4_driver_data *idd;
 
-       down_write(&ioc4_submodules_rwsem);
+       mutex_lock(&ioc4_mutex);
        list_del(&is->is_list);
-       up_write(&ioc4_submodules_rwsem);
 
        /* Remove submodule for each IOC4 */
        if (!is->is_remove)
-               return;
+               goto out;
 
-       down_read(&ioc4_devices_rwsem);
        list_for_each_entry(idd, &ioc4_devices, idd_list) {
                if (is->is_remove(idd)) {
                        printk(KERN_WARNING
                               pci_name(idd->idd_pdev));
                }
        }
-       up_read(&ioc4_devices_rwsem);
+ out:
+       mutex_unlock(&ioc4_mutex);
 }
 
 /*********************
        /* Track PCI-device specific data */
        idd->idd_serial_data = NULL;
        pci_set_drvdata(idd->idd_pdev, idd);
-       down_write(&ioc4_devices_rwsem);
+
+       mutex_lock(&ioc4_mutex);
        list_add(&idd->idd_list, &ioc4_devices);
-       up_write(&ioc4_devices_rwsem);
 
        /* Add this IOC4 to all submodules */
-       down_read(&ioc4_submodules_rwsem);
        list_for_each_entry(is, &ioc4_submodules, is_list) {
                if (is->is_probe && is->is_probe(idd)) {
                        printk(KERN_WARNING
                               pci_name(idd->idd_pdev));
                }
        }
-       up_read(&ioc4_submodules_rwsem);
+       mutex_unlock(&ioc4_mutex);
 
        return 0;
 
        idd = pci_get_drvdata(pdev);
 
        /* Remove this IOC4 from all submodules */
-       down_read(&ioc4_submodules_rwsem);
+       mutex_lock(&ioc4_mutex);
        list_for_each_entry(is, &ioc4_submodules, is_list) {
                if (is->is_remove && is->is_remove(idd)) {
                        printk(KERN_WARNING
                               pci_name(idd->idd_pdev));
                }
        }
-       up_read(&ioc4_submodules_rwsem);
+       mutex_unlock(&ioc4_mutex);
 
        /* Release resources */
        iounmap(idd->idd_misc_regs);
        pci_disable_device(pdev);
 
        /* Remove and free driver data */
-       down_write(&ioc4_devices_rwsem);
+       mutex_lock(&ioc4_mutex);
        list_del(&idd->idd_list);
-       up_write(&ioc4_devices_rwsem);
+       mutex_unlock(&ioc4_mutex);
        kfree(idd);
 }