Am Dienstag, 22. Mai 2007 17:12 schrieb Alan Stern:
> Very good. I did notice two more things:
>
> Timeouts are specified in jiffies, so your timeout argument
> should be long or unsigned long, not int.
>
> There's a race if two threads call usb_unanchor_urb() for the
> same URB at the same time. You need to recheck while holding
> the anchor's spinlock that urb->anchor is still equal to
> anchor. You might also want to add
>
> WARN_ON(urb->anchor != NULL);
>
> to usb_anchor_urb(), just as a precaution.
OK, these are fixed and the timeout given in milliseconds, as David
recommended.
I looked into the inlining issue and the inlined version wins in terms
of size.
Regards
Oliver
-----
--- a/include/linux/usb.h 2007-05-22 14:51:01.000000000 +0200
+++ b/include/linux/usb.h 2007-05-23 10:20:35.000000000 +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 +1287,11 @@ 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, unsigned long 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 2007-05-22 14:50:32.000000000 +0200
+++ b/drivers/usb/core/hcd.c 2007-05-22 15:36:17.000000000 +0200
@@ -1412,6 +1412,8 @@ 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 2007-05-22 14:40:12.000000000 +0200
+++ b/drivers/usb/core/urb.c 2007-05-23 10:20:01.000000000 +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 +103,60 @@ struct urb * usb_get_urb(struct urb *urb
kref_get(&urb->kref);
return urb;
}
-
-
+
+/**
+ * usb_anchor_urb - anchors an URB while it is processed
+ * @urb: pointer to the urb to anchor
+ * @anchor: 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);
+}
+
+/**
+ * usb_unanchor_urb - unanchors an URB
+ * @urb: pointer to the urb to anchor
+ *
+ * Call this to stop the system keeping track of this URB
+ */
+
+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);
+ if (unlikely(anchor != urb->anchor)) {
+ /* we've lost the race to another thread */
+ spin_unlock_irqrestore(&anchor->lock, flags);
+ return;
+ }
+ 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 +532,57 @@ void usb_kill_urb(struct urb *urb)
--urb->reject;
spin_unlock_irq(&urb->lock);
}
+/**
+ * usb_kill_anchored_urbs - cancel transfer requests en masse
+ * @anchor: anchor the requests are bound to
+ *
+ * this allows all outstanding URBs to be killed starting
+ * from the back of the queue
+ */
+
+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);
+}
+
+/**
+ * usb_wait_anchor_empty_timeout - wait for an anchor to be unused
+ * @anchor: the anchor you want to become unused
+ * @timeout: how long you are willing to wait in milliseconds
+ *
+ * Call this is you want to be sure all an anchor's
+ * URBs have finished
+ */
+
+int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor, unsigned long
timeout)
+{
+ int res;
+
+ res = wait_event_timeout(anchor->wait, list_empty(&anchor->urb_list),
timeout * HZ / 1000);
+ 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_unanchor_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);
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