On Tue, 29 Jan 2008, Peter Korsgaard wrote:
> This patch adds HCD support for the Cypress c67x00 family of devices.
> --- /dev/null
> +++ linux-2.6/drivers/usb/c67x00/c67x00-hcd.c
> +int c67x00_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
> +{
> + struct c67x00_hcd *c67x00 = hcd_to_c67x00_hcd(hcd);
> + unsigned long flags;
> + int rc;
> +
> + spin_lock_irqsave(&c67x00->lock, flags);
> + rc = usb_hcd_check_unlink_urb(hcd, urb, status);
> + if (rc)
> + goto done;
> +
> + c67x00_release_urb(c67x00, urb);
> + usb_hcd_unlink_urb_from_ep(hcd, urb);
> + spin_unlock_irqrestore(&c67x00->lock, flags);
> +
> + usb_hcd_giveback_urb(hcd, urb, status);
This is wrong. usb_hcd_giveback_urb() must be called with local
interrupts disabled.
> +/*
> + * pre: urb != NULL and c67x00 locked, urb unlocked
> + */
> +static inline void
> +c67x00_giveback_urb(struct c67x00_hcd *c67x00, struct urb *urb, int status)
> +{
> + struct c67x00_urb_priv *urbp;
> +
> + if (!urb)
> + return;
Since you have the documented precondition that urb != NULL, and since
this routine is never called in a context where urb could be NULL,
there's no need for this test. Also, I doubt that this routine really
needs to be inline (and besides, the compiler is better at making such
decisions than we are).
> +static void c67x00_sched_done(unsigned long __c67x00)
> +{
> + struct c67x00_hcd *c67x00 = (struct c67x00_hcd *)__c67x00;
> + struct c67x00_urb_priv *urbp, *tmp;
> + struct urb *urb;
> +
> + spin_lock(&c67x00->lock);
> +
> + /* Loop over the done list and give back all the urbs */
> + list_for_each_entry_safe(urbp, tmp, &c67x00->done_list, hep_node) {
> + urb = urbp->urb;
> + c67x00_release_urb(c67x00, urb);
> + if (!usb_hcd_check_unlink_urb(c67x00_hcd_to_hcd(c67x00),
> + urb, urbp->status)) {
The function call above is completely wrong. It is meant to be used only
from within the dequeue method.
> + usb_hcd_unlink_urb_from_ep(c67x00_hcd_to_hcd(c67x00),
> + urb);
> + spin_unlock(&c67x00->lock);
> + usb_hcd_giveback_urb(c67x00_hcd_to_hcd(c67x00), urb,
> + urbp->status);
> + spin_lock(&c67x00->lock);
> + }
> + }
> + spin_unlock(&c67x00->lock);
> +}
Is there some reason this routine needs to run in a tasklet? Why not
just call it directly?
Also, the fact that it is in a tasklet means that it runs with
interrupts enabled. Hence your spin_lock() and spin_unlock() calls
will not do the right thing.
Alan Stern
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