4 files changed, 137 insertions, 45 deletions

diff --git a/drivers/usb/usbip/stub_dev.c b/drivers/usb/usbip/stub_dev.c
index a3ec49b..e286346 100644
--- a/drivers/usb/usbip/stub_dev.c
+++ b/drivers/usb/usbip/stub_dev.c
@@ -388,7 +388,6 @@ err_files:
 err_port:
 	dev_set_drvdata(&udev->dev, NULL);
 	usb_put_dev(udev);
-	kthread_stop_put(sdev->ud.eh);
 
 	busid_priv->sdev = NULL;
 	stub_device_free(sdev);
@@ -449,7 +448,7 @@ static void stub_disconnect(struct usb_device *udev)
 	}
 
 	/* If usb reset is called from event handler */
-	if (busid_priv->sdev->ud.eh == current)
+	if (usbip_in_eh(current))
 		return;
 
 	/* shutdown the current connection */
diff --git a/drivers/usb/usbip/usbip_common.c b/drivers/usb/usbip/usbip_common.c
index e40da77..2e5cf63 100644
--- a/drivers/usb/usbip/usbip_common.c
+++ b/drivers/usb/usbip/usbip_common.c
@@ -769,12 +769,19 @@ EXPORT_SYMBOL_GPL(usbip_recv_xbuff);
 
 static int __init usbip_core_init(void)
 {
+	int ret;
+
 	pr_info(DRIVER_DESC " v" USBIP_VERSION "\n");
+	ret = usbip_init_eh();
+	if (ret)
+		return ret;
+
 	return 0;
 }
 
 static void __exit usbip_core_exit(void)
 {
+	usbip_finish_eh();
 	return;
 }
 
diff --git a/drivers/usb/usbip/usbip_common.h b/drivers/usb/usbip/usbip_common.h
index 86b0847..2fbbc64 100644
--- a/drivers/usb/usbip/usbip_common.h
+++ b/drivers/usb/usbip/usbip_common.h
@@ -267,7 +267,6 @@ struct usbip_device {
 	struct task_struct *tcp_tx;
 
 	unsigned long event;
-	struct task_struct *eh;
 	wait_queue_head_t eh_waitq;
 
 	struct eh_ops {
@@ -313,10 +312,13 @@ void usbip_pad_iso(struct usbip_device *ud, struct urb *urb);
 int usbip_recv_xbuff(struct usbip_device *ud, struct urb *urb);
 
 /* usbip_event.c */
+int usbip_init_eh(void);
+void usbip_finish_eh(void);
 int usbip_start_eh(struct usbip_device *ud);
 void usbip_stop_eh(struct usbip_device *ud);
 void usbip_event_add(struct usbip_device *ud, unsigned long event);
 int usbip_event_happened(struct usbip_device *ud);
+int usbip_in_eh(struct task_struct *task);
 
 static inline int interface_to_busnum(struct usb_interface *interface)
 {
diff --git a/drivers/usb/usbip/usbip_event.c b/drivers/usb/usbip/usbip_event.c
index 2580a32..f163566 100644
--- a/drivers/usb/usbip/usbip_event.c
+++ b/drivers/usb/usbip/usbip_event.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ * Copyright (C) 2015 Nobuo Iwata
  *
  * This is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -19,17 +20,68 @@
 
 #include <linux/kthread.h>
 #include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
 
 #include "usbip_common.h"
 
-static int event_handler(struct usbip_device *ud)
+struct usbip_event {
+	struct list_head node;
+	struct usbip_device *ud;
+};
+
+static DEFINE_SPINLOCK(event_lock);
+static LIST_HEAD(event_list);
+
+static void set_event(struct usbip_device *ud, unsigned long event)
 {
-	usbip_dbg_eh("enter\n");
+	unsigned long flags;
 
-	/*
-	 * Events are handled by only this thread.
-	 */
-	while (usbip_event_happened(ud)) {
+	spin_lock_irqsave(&ud->lock, flags);
+	ud->event |= event;
+	spin_unlock_irqrestore(&ud->lock, flags);
+}
+
+static void unset_event(struct usbip_device *ud, unsigned long event)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ud->lock, flags);
+	ud->event &= ~event;
+	spin_unlock_irqrestore(&ud->lock, flags);
+}
+
+static struct usbip_device *get_event(void)
+{
+	struct usbip_event *ue = NULL;
+	struct usbip_device *ud = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&event_lock, flags);
+	if (!list_empty(&event_list)) {
+		ue = list_first_entry(&event_list, struct usbip_event, node);
+		list_del(&ue->node);
+	}
+	spin_unlock_irqrestore(&event_lock, flags);
+
+	if (ue) {
+		ud = ue->ud;
+		kfree(ue);
+	}
+	return ud;
+}
+
+static struct task_struct *worker_context;
+
+static void event_handler(struct work_struct *work)
+{
+	struct usbip_device *ud;
+
+	if (worker_context == NULL) {
+		worker_context = current;
+	}
+
+	while ((ud = get_event()) != NULL) {
 		usbip_dbg_eh("pending event %lx\n", ud->event);
 
 		/*
@@ -38,79 +90,102 @@ static int event_handler(struct usbip_device *ud)
 		 */
 		if (ud->event & USBIP_EH_SHUTDOWN) {
 			ud->eh_ops.shutdown(ud);
-			ud->event &= ~USBIP_EH_SHUTDOWN;
+			unset_event(ud, USBIP_EH_SHUTDOWN);
 		}
 
 		/* Reset the device. */
 		if (ud->event & USBIP_EH_RESET) {
 			ud->eh_ops.reset(ud);
-			ud->event &= ~USBIP_EH_RESET;
+			unset_event(ud, USBIP_EH_RESET);
 		}
 
 		/* Mark the device as unusable. */
 		if (ud->event & USBIP_EH_UNUSABLE) {
 			ud->eh_ops.unusable(ud);
-			ud->event &= ~USBIP_EH_UNUSABLE;
+			unset_event(ud, USBIP_EH_UNUSABLE);
 		}
 
 		/* Stop the error handler. */
 		if (ud->event & USBIP_EH_BYE)
-			return -1;
+			usbip_dbg_eh("removed %p\n", ud);
+
+		wake_up(&ud->eh_waitq);
 	}
+}
 
+int usbip_start_eh(struct usbip_device *ud)
+{
+	init_waitqueue_head(&ud->eh_waitq);
+	ud->event = 0;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(usbip_start_eh);
 
-static int event_handler_loop(void *data)
+void usbip_stop_eh(struct usbip_device *ud)
 {
-	struct usbip_device *ud = data;
+	unsigned long pending = ud->event & ~USBIP_EH_BYE;
 
-	while (!kthread_should_stop()) {
-		wait_event_interruptible(ud->eh_waitq,
-					 usbip_event_happened(ud) ||
-					 kthread_should_stop());
-		usbip_dbg_eh("wakeup\n");
+	if (!(ud->event & USBIP_EH_BYE))
+		usbip_dbg_eh("usbip_eh stopping but not removed\n");
 
-		if (event_handler(ud) < 0)
-			break;
-	}
+	if (pending)
+		usbip_dbg_eh("usbip_eh waiting completion %lx\n", pending);
 
-	return 0;
+	wait_event_interruptible(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE));
+	usbip_dbg_eh("usbip_eh has stopped\n");
 }
+EXPORT_SYMBOL_GPL(usbip_stop_eh);
 
-int usbip_start_eh(struct usbip_device *ud)
-{
-	init_waitqueue_head(&ud->eh_waitq);
-	ud->event = 0;
+#define WORK_QUEUE_NAME "usbip_event"
 
-	ud->eh = kthread_run(event_handler_loop, ud, "usbip_eh");
-	if (IS_ERR(ud->eh)) {
-		pr_warn("Unable to start control thread\n");
-		return PTR_ERR(ud->eh);
-	}
+static struct workqueue_struct *usbip_queue;
+static DECLARE_WORK(usbip_work, event_handler);
 
+int usbip_init_eh(void)
+{
+	usbip_queue = create_singlethread_workqueue(WORK_QUEUE_NAME);
+	if (usbip_queue == NULL) {
+		pr_err("failed to create usbip_event\n");
+		return -ENOMEM;
+	}
 	return 0;
 }
-EXPORT_SYMBOL_GPL(usbip_start_eh);
 
-void usbip_stop_eh(struct usbip_device *ud)
+void usbip_finish_eh(void)
 {
-	if (ud->eh == current)
-		return; /* do not wait for myself */
-
-	kthread_stop(ud->eh);
-	usbip_dbg_eh("usbip_eh has finished\n");
+	flush_workqueue(usbip_queue);
+	destroy_workqueue(usbip_queue);
+	usbip_queue = NULL;
 }
-EXPORT_SYMBOL_GPL(usbip_stop_eh);
 
 void usbip_event_add(struct usbip_device *ud, unsigned long event)
 {
+	struct usbip_event *ue;
 	unsigned long flags;
 
-	spin_lock_irqsave(&ud->lock, flags);
-	ud->event |= event;
-	wake_up(&ud->eh_waitq);
-	spin_unlock_irqrestore(&ud->lock, flags);
+	if (ud->event & USBIP_EH_BYE)
+		return;
+
+	set_event(ud, event);
+
+	spin_lock_irqsave(&event_lock, flags);
+
+	list_for_each_entry_reverse(ue, &event_list, node) {
+		if (ue->ud == ud)
+			goto out;
+	}
+
+	ue = kmalloc(sizeof(struct usbip_event), GFP_ATOMIC);
+	if (ue == NULL)
+		goto out;
+
+	ue->ud = ud;
+
+	list_add_tail(&ue->node, &event_list);
+	queue_work(usbip_queue, &usbip_work);
+
+out:
+	spin_unlock_irqrestore(&event_lock, flags);
 }
 EXPORT_SYMBOL_GPL(usbip_event_add);
 
@@ -127,3 +202,12 @@ int usbip_event_happened(struct usbip_device *ud)
 	return happened;
 }
 EXPORT_SYMBOL_GPL(usbip_event_happened);
+
+int usbip_in_eh(struct task_struct *task)
+{
+	if (task == worker_context)
+		return 1;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbip_in_eh);