/* * libusual * * The libusual contains the table of devices common for ub and usb-storage. */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/usb.h> #include <linux/usb_usual.h> #include <linux/vmalloc.h> #include <linux/kthread.h> #include <linux/mutex.h> /* */ #define USU_MOD_FL_THREAD 1 /* Thread is running */ #define USU_MOD_FL_PRESENT 2 /* The module is loaded */ struct mod_status { unsigned long fls; }; static struct mod_status stat[3]; static DEFINE_SPINLOCK(usu_lock); /* */ #define USB_US_DEFAULT_BIAS USB_US_TYPE_STOR static atomic_t usu_bias = ATOMIC_INIT(USB_US_DEFAULT_BIAS); #define BIAS_NAME_SIZE (sizeof("usb-storage")) static const char *bias_names[3] = { "none", "usb-storage", "ub" }; static DEFINE_MUTEX(usu_probe_mutex); static DECLARE_COMPLETION(usu_end_notify); static atomic_t total_threads = ATOMIC_INIT(0); static int usu_probe_thread(void *arg); /* * @type: the module type as an integer */ void usb_usual_set_present(int type) { struct mod_status *st; unsigned long flags; if (type <= 0 || type >= 3) return; st = &stat[type]; spin_lock_irqsave(&usu_lock, flags); st->fls |= USU_MOD_FL_PRESENT; spin_unlock_irqrestore(&usu_lock, flags); } EXPORT_SYMBOL_GPL(usb_usual_set_present); void usb_usual_clear_present(int type) { struct mod_status *st; unsigned long flags; if (type <= 0 || type >= 3) return; st = &stat[type]; spin_lock_irqsave(&usu_lock, flags); st->fls &= ~USU_MOD_FL_PRESENT; spin_unlock_irqrestore(&usu_lock, flags); } EXPORT_SYMBOL_GPL(usb_usual_clear_present); /* * Match the calling driver type against the table. * Returns: 0 if the device matches. */ int usb_usual_check_type(const struct usb_device_id *id, int caller_type) { int id_type = USB_US_TYPE(id->driver_info); if (caller_type <= 0 || caller_type >= 3) return -EINVAL; /* Drivers grab fixed assignment devices */ if (id_type == caller_type) return 0; /* Drivers grab devices biased to them */ if (id_type == USB_US_TYPE_NONE && caller_type == atomic_read(&usu_bias)) return 0; return -ENODEV; } EXPORT_SYMBOL_GPL(usb_usual_check_type); /* */ static int usu_probe(struct usb_interface *intf, const struct usb_device_id *id) { int rc; unsigned long type; struct task_struct* task; unsigned long flags; type = USB_US_TYPE(id->driver_info); if (type == 0) type = atomic_read(&usu_bias); spin_lock_irqsave(&usu_lock, flags); if ((stat[type].fls & (USU_MOD_FL_THREAD|USU_MOD_FL_PRESENT)) != 0) { spin_unlock_irqrestore(&usu_lock, flags); return -ENXIO; } stat[type].fls |= USU_MOD_FL_THREAD; spin_unlock_irqrestore(&usu_lock, flags); task = kthread_run(usu_probe_thread, (void*)type, "libusual_%ld", type); if (IS_ERR(task)) { rc = PTR_ERR(task); printk(KERN_WARNING "libusual: " "Unable to start the thread for %s: %d\n", bias_names[type], rc); spin_lock_irqsave(&usu_lock, flags); stat[type].fls &= ~USU_MOD_FL_THREAD; spin_unlock_irqrestore(&usu_lock, flags); return rc; /* Not being -ENXIO causes a message printed */ } atomic_inc(&total_threads); return -ENXIO; } static void usu_disconnect(struct usb_interface *intf) { ; /* We should not be here. */ } static struct usb_driver usu_driver = { .name = "libusual", .probe = usu_probe, .disconnect = usu_disconnect, .id_table = usb_storage_usb_ids, }; /* * A whole new thread for a purpose of request_module seems quite stupid. * The request_module forks once inside again. However, if we attempt * to load a storage module from our own modprobe thread, that module * references our symbols, which cannot be resolved until our module is * initialized. I wish there was a way to wait for the end of initialization. * The module notifier reports MODULE_STATE_COMING only. * So, we wait until module->init ends as the next best thing. */ static int usu_probe_thread(void *arg) { int type = (unsigned long) arg; struct mod_status *st = &stat[type]; int rc; unsigned long flags; mutex_lock(&usu_probe_mutex); rc = request_module(bias_names[type]); spin_lock_irqsave(&usu_lock, flags); if (rc == 0 && (st->fls & USU_MOD_FL_PRESENT) == 0) { /* * This should not happen, but let us keep tabs on it. */ printk(KERN_NOTICE "libusual: " "modprobe for %s succeeded, but module is not present\n", bias_names[type]); } st->fls &= ~USU_MOD_FL_THREAD; spin_unlock_irqrestore(&usu_lock, flags); mutex_unlock(&usu_probe_mutex); complete_and_exit(&usu_end_notify, 0); } /* */ static int __init usb_usual_init(void) { int rc; mutex_lock(&usu_probe_mutex); rc = usb_register(&usu_driver); mutex_unlock(&usu_probe_mutex); return rc; } static void __exit usb_usual_exit(void) { /* * We do not check for any drivers present, because * they keep us pinned with symbol references. */ usb_deregister(&usu_driver); while (atomic_read(&total_threads) > 0) { wait_for_completion(&usu_end_notify); atomic_dec(&total_threads); } } /* * Validate and accept the bias parameter. */ static int usu_set_bias(const char *bias_s, struct kernel_param *kp) { int i; int len; int bias_n = 0; len = strlen(bias_s); if (len == 0) return -EDOM; if (bias_s[len-1] == '\n') --len; for (i = 1; i < 3; i++) { if (strncmp(bias_s, bias_names[i], len) == 0) { bias_n = i; break; } } if (bias_n == 0) return -EINVAL; atomic_set(&usu_bias, bias_n); return 0; } static int usu_get_bias(char *buffer, struct kernel_param *kp) { return strlen(strcpy(buffer, bias_names[atomic_read(&usu_bias)])); } module_init(usb_usual_init); module_exit(usb_usual_exit); module_param_call(bias, usu_set_bias, usu_get_bias, NULL, S_IRUGO|S_IWUSR); __MODULE_PARM_TYPE(bias, "string"); MODULE_PARM_DESC(bias, "Bias to usb-storage or ub"); MODULE_LICENSE("GPL");