Re: requirements for suspend()

Am Montag, 7. Mai 2007 21:23 schrieb Alan Stern:
> On Mon, 7 May 2007, Oliver Neukum wrote:

> > +int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor, int timeout)
> > +{
> > +	int res;
> > +
> > +	res = wait_event_timeout(anchor->wait, list_empty(&anchor->urb_list), timeout);
> 
> Maybe make this an interruptible wait?

For use in disconnect(), suspend() and pre_reset()? Theses can't handle
signals.
 
> In general the fire-and-forget model has to work that way.  URBs and their
> buffers will be freed by the completion handler.

Ok. I've followed all other your suggestions.

	Regards
		Oliver
---

--- a/include/linux/usb.h	2007-05-04 10:50:18.000000000 +0200
+++ b/include/linux/usb.h	2007-05-08 12:47:27.000000000 +0200
@@ -958,11 +958,26 @@ struct usb_iso_packet_descriptor {
 
 struct urb;
 
+struct usb_anchor {
+	struct list_head urb_list;
+	wait_queue_head_t wait;
+	spinlock_t lock;
+};
+
+static inline void init_usb_anchor(struct usb_anchor *anchor)
+{
+	INIT_LIST_HEAD(&anchor->urb_list);
+	init_waitqueue_head(&anchor->wait);
+	spin_lock_init(&anchor->lock);
+}
+
 typedef void (*usb_complete_t)(struct urb *);
 
 /**
  * struct urb - USB Request Block
  * @urb_list: For use by current owner of the URB.
+ * @anchor_list: membership in the list of an anchor
+ * @anchor: to anchor URBs to a common mooring
  * @pipe: Holds endpoint number, direction, type, and more.
  *	Create these values with the eight macros available;
  *	usb_{snd,rcv}TYPEpipe(dev,endpoint), where the TYPE is "ctrl"
@@ -1135,6 +1150,8 @@ struct urb
 	/* public: documented fields in the urb that can be used by drivers */
 	struct list_head urb_list;	/* list head for use by the urb's
 					 * current owner */
+	struct list_head anchor_list;	/* the URB may be anchored by the driver */
+	struct usb_anchor *anchor;
 	struct usb_device *dev; 	/* (in) pointer to associated device */
 	unsigned int pipe;		/* (in) pipe information */
 	int status;			/* (return) non-ISO status */
@@ -1270,6 +1287,10 @@ extern struct urb *usb_get_urb(struct ur
 extern int usb_submit_urb(struct urb *urb, gfp_t mem_flags);
 extern int usb_unlink_urb(struct urb *urb);
 extern void usb_kill_urb(struct urb *urb);
+extern void usb_kill_anchored_urbs(struct usb_anchor *anchor);
+extern void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor);
+extern void usb_unanchor_urb(struct urb *urb);
+extern int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor, int timeout);
 
 void *usb_buffer_alloc (struct usb_device *dev, size_t size,
 	gfp_t mem_flags, dma_addr_t *dma);
--- a/drivers/usb/core/hcd.c	2007-05-04 12:04:29.000000000 +0200
+++ b/drivers/usb/core/hcd.c	2007-05-07 15:19:01.000000000 +0200
@@ -1408,6 +1408,8 @@ void usb_hcd_giveback_urb (struct usb_hc
 	}
 
 	usbmon_urb_complete (&hcd->self, urb);
+	usb_unanchor_urb(urb);
+
 	/* pass ownership to the completion handler */
 	urb->complete (urb);
 	atomic_dec (&urb->use_count);
--- a/drivers/usb/core/urb.c	2007-05-04 10:53:14.000000000 +0200
+++ b/drivers/usb/core/urb.c	2007-05-08 13:07:37.000000000 +0200
@@ -4,6 +4,7 @@
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/usb.h>
+#include <linux/wait.h>
 #include "hcd.h"
 
 #define to_urb(d) container_of(d, struct urb, kref)
@@ -11,6 +12,7 @@
 static void urb_destroy(struct kref *kref)
 {
 	struct urb *urb = to_urb(kref);
+
 	kfree(urb);
 }
 
@@ -34,6 +36,7 @@ void usb_init_urb(struct urb *urb)
 		memset(urb, 0, sizeof(*urb));
 		kref_init(&urb->kref);
 		spin_lock_init(&urb->lock);
+		INIT_LIST_HEAD(&urb->anchor_list);
 	}
 }
 
@@ -100,8 +103,48 @@ struct urb * usb_get_urb(struct urb *urb
 		kref_get(&urb->kref);
 	return urb;
 }
-		
-		
+
+/**
+ * usb_associate_urb_to_anchor - anchors an URB while it is processed
+ * @u: pointer to the urb to anchor
+ * @a: pointer to the anchor
+ *
+ * This can be called to have access to URBs which are to be executed
+ * without bothering to track them
+ */
+
+void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&anchor->lock, flags);
+	usb_get_urb(urb);
+	list_add_tail(&urb->anchor_list, &anchor->urb_list);
+	urb->anchor = anchor;
+	spin_unlock_irqrestore(&anchor->lock, flags);
+}
+
+void usb_unanchor_urb(struct urb *urb)
+{
+	unsigned long flags;
+	struct usb_anchor *anchor;
+
+	if (!urb)
+		return;
+
+	anchor = urb->anchor;
+	if (!anchor)
+		return;
+
+	spin_lock_irqsave(&anchor->lock, flags);
+	urb->anchor = NULL;
+	list_del(&urb->anchor_list);
+	spin_unlock_irqrestore(&anchor->lock, flags);
+	usb_put_urb(urb);
+	if (list_empty(&anchor->urb_list))
+		wake_up(&anchor->wait);
+}
+
 /*-------------------------------------------------------------------*/
 
 /**
@@ -477,12 +520,49 @@ void usb_kill_urb(struct urb *urb)
 	--urb->reject;
 	spin_unlock_irq(&urb->lock);
 }
+/**
+ * usb_kill_associated_urbs - cancel transfer requests en masse
+ * @old: anchor the requests are bound to
+ * @new: anchor the request which were canceled shall be bound to, may be NULL
+ *
+ * this allows all outstanding URBs to be cancelled and bound to an anchor
+ * for later processing
+ */
+
+void usb_kill_anchored_urbs(struct usb_anchor *anchor)
+{
+	struct urb *victim;
+
+	spin_lock_irq(&anchor->lock);
+	while (!list_empty(&anchor->urb_list)) {
+		victim = list_entry(anchor->urb_list.prev, struct urb, anchor_list);
+		/* we must make sure the URB isn't freed before we kill it*/
+		usb_get_urb(victim);
+		spin_unlock_irq(&anchor->lock);
+		/* this will unanchor the URB */
+		usb_kill_urb(victim);
+		usb_put_urb(victim);
+		spin_lock_irq(&anchor->lock);
+	}
+	spin_unlock_irq(&anchor->lock);
+}
+
+int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor, int timeout)
+{
+	int res;
+
+	res = wait_event_timeout(anchor->wait, list_empty(&anchor->urb_list), timeout);
+	return res;
+}
 
 EXPORT_SYMBOL(usb_init_urb);
 EXPORT_SYMBOL(usb_alloc_urb);
 EXPORT_SYMBOL(usb_free_urb);
 EXPORT_SYMBOL(usb_get_urb);
+EXPORT_SYMBOL(usb_anchor_urb);
 EXPORT_SYMBOL(usb_submit_urb);
 EXPORT_SYMBOL(usb_unlink_urb);
 EXPORT_SYMBOL(usb_kill_urb);
+EXPORT_SYMBOL(usb_kill_anchored_urbs);
+EXPORT_SYMBOL(usb_wait_anchor_empty_timeout);
 
--- a/drivers/usb/usb-skeleton.c	2007-05-04 13:07:30.000000000 +0200
+++ b/drivers/usb/usb-skeleton.c	2007-05-08 13:41:34.000000000 +0200
@@ -54,10 +54,13 @@ struct usb_skel {
 	struct usb_device	*udev;			/* the usb device for this device */
 	struct usb_interface	*interface;		/* the interface for this device */
 	struct semaphore	limit_sem;		/* limiting the number of writes in progress */
+	struct usb_anchor	submitted;		/* in case we need to retract our submissions */
 	unsigned char           *bulk_in_buffer;	/* the buffer to receive data */
 	size_t			bulk_in_size;		/* the size of the receive buffer */
 	__u8			bulk_in_endpointAddr;	/* the address of the bulk in endpoint */
 	__u8			bulk_out_endpointAddr;	/* the address of the bulk out endpoint */
+	int			errors;			/* the last request tanked */
+	spinlock_t		err_lock;		/* lock for errors */
 	struct kref		kref;
 	struct mutex		io_mutex;		/* synchronize I/O with disconnect */
 };
@@ -179,14 +182,17 @@ static void skel_write_bulk_callback(str
 	dev = (struct usb_skel *)urb->context;
 
 	/* sync/async unlink faults aren't errors */
-	if (urb->status &&
-	    !(urb->status == -ENOENT ||
-	      urb->status == -ECONNRESET ||
-	      urb->status == -ESHUTDOWN)) {
-		err("%s - nonzero write bulk status received: %d",
-		    __FUNCTION__, urb->status);
+	if (urb->status) {
+		if (!(urb->status == -ENOENT ||
+		      urb->status == -ECONNRESET ||
+		      urb->status == -ESHUTDOWN)) {
+			err("%s - nonzero write bulk status received: %d",
+			__FUNCTION__, urb->status);
+		}
+		spin_lock(&dev->err_lock);
+		dev->errors = urb->status;
+		spin_unlock(&dev->err_lock);
 	}
-
 	/* free up our allocated buffer */
 	usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 			urb->transfer_buffer, urb->transfer_dma);
@@ -213,6 +219,15 @@ static ssize_t skel_write(struct file *f
 		goto exit;
 	}
 
+	spin_lock_irq(&dev->err_lock);
+	if (dev->errors < 0) {
+		dev->errors = 0;
+		retval = -EIO;
+	}
+	spin_unlock_irq(&dev->err_lock);
+	if (retval < 0)
+		goto error;
+
 	/* create a urb, and a buffer for it, and copy the data to the urb */
 	urb = usb_alloc_urb(0, GFP_KERNEL);
 	if (!urb) {
@@ -244,6 +259,7 @@ static ssize_t skel_write(struct file *f
 			  usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 			  buf, writesize, skel_write_bulk_callback, dev);
 	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	usb_anchor_urb(urb, &dev->submitted);
 
 	/* send the data out the bulk port */
 	retval = usb_submit_urb(urb, GFP_KERNEL);
@@ -306,6 +322,8 @@ static int skel_probe(struct usb_interfa
 	kref_init(&dev->kref);
 	sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 	mutex_init(&dev->io_mutex);
+	spin_lock_init(&dev->err_lock);
+	init_usb_anchor(&dev->submitted);
 
 	dev->udev = usb_get_dev(interface_to_usbdev(interface));
 	dev->interface = interface;
@@ -383,7 +401,7 @@ static void skel_disconnect(struct usb_i
 	dev->interface = NULL;
 	mutex_unlock(&dev->io_mutex);
 
-
+	usb_kill_anchored_urbs(&dev->submitted);
 
 	/* decrement our usage count */
 	kref_put(&dev->kref, skel_delete);
@@ -391,10 +409,31 @@ static void skel_disconnect(struct usb_i
 	info("USB Skeleton #%d now disconnected", minor);
 }
 
+static int skel_suspend(struct usb_interface *intf, pm_message_t message)
+{
+	struct usb_skel *dev= usb_get_intfdata(intf);
+	int time;
+
+	mutex_lock(&dev->io_mutex);
+	time = usb_wait_anchor_empty_timeout(&dev->submitted, 1 * HZ);
+	if (!time)
+		usb_kill_anchored_urbs(&dev->submitted);
+	mutex_unlock(&dev->io_mutex);
+
+	return 0;
+}
+
+static int skel_resume (struct usb_interface *intf)
+{
+	return 0;
+}
+
 static struct usb_driver skel_driver = {
 	.name =		"skeleton",
 	.probe =	skel_probe,
 	.disconnect =	skel_disconnect,
+	.suspend =	skel_suspend,
+	.resume =	skel_resume,
 	.id_table =	skel_table,
 	.supports_autosuspend = 1,
 };

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