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

2007-10-27 Thread Alan Stern 
On Thu, 25 Oct 2007, Greg KH wrote:

> On Tue, Oct 23, 2007 at 12:01:37AM -0400, Alan Stern wrote:
> > 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 <[EMAIL PROTECTED]>
> 
> Alan, is this something you want added to the tree and in before 2.6.24
> is out?

Yes.  It's a small thing, but we're better off keeping IRQ
enable/disable calls properly balanced.

Alan Stern

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

2007-10-25 Thread Greg KH 
On Tue, Oct 23, 2007 at 12:01:37AM -0400, Alan Stern wrote:
> 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 <[EMAIL PROTECTED]>

Alan, is this something you want added to the tree and in before 2.6.24
is out?

thanks,

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

2007-10-22 Thread 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 <[EMAIL PROTECTED]>

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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