Re: [linux-usb-devel] USB HCD: avoid duplicate local_irq_disable()

[Alan Stern]

On Tue, 23 Oct 2007, Arnd Bergmann wrote:

> usb_hcd_flush_endpoint() has a retry loop that starts with a spin_lock_irq(),
> but only gives up the spinlock, not the irq_disable before jumping to the
> rescan label.
> 
> Split the spin_lock_irq into the retryable part and the local_irq_disable()
> that is only done once as a micro-optimization and slight cleanup.

I agree with your sentiment, but it would be better to solve this 
problem without using local_irq_disable().  The patch below does this.

---

Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>

Index: usb-2.6/drivers/usb/core/hcd.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/hcd.c
+++ usb-2.6/drivers/usb/core/hcd.c
@@ -1312,8 +1312,8 @@ void usb_hcd_flush_endpoint(struct usb_d
 	hcd = bus_to_hcd(udev->bus);
 
 	/* No more submits can occur */
-rescan:
 	spin_lock_irq(&hcd_urb_list_lock);
+rescan:
 	list_for_each_entry (urb, &ep->urb_list, urb_list) {
 		int	is_in;
 
@@ -1346,6 +1346,7 @@ rescan:
 		usb_put_urb (urb);
 
 		/* list contents may have changed */
+		spin_lock(&hcd_urb_list_lock);
 		goto rescan;
 	}
 	spin_unlock_irq(&hcd_urb_list_lock);

-
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