Am Mittwoch, 21. September 2005 20:04 schrieb David Kubicek:
> On Wed, Sep 21, 2005 at 06:32:05PM +0200, Oliver Neukum wrote:
> > Am Mittwoch, 21. September 2005 14:51 schrieb David Kubicek:
> > This is in interrupt. Please use the simple form of the locks.
> I'd like to find out the difference between and in which context to
> use the following locking -- could anyone help, please (even URL)?
> 1) spin_lock_irqsave
> 2) spin_lock_irq
> 3) spin_lock
>
> > Please rename the structure so it is not mistaken for the actual buffer.
> I have renamed some other structures and variables as well to blend them
> in with existing code.
spin_unlock(&acm->throttle_lock);
- urb->actual_length = 0;
- urb->dev = acm->dev;
-
- i = usb_submit_urb(urb, GFP_ATOMIC);
- if (i)
- dev_dbg(&acm->data->dev, "bulk rx resubmit %d\n", i);
+ spin_lock_irqsave(&acm->read_lock, flags);
+ list_add(&buf->list, &acm->spare_read_bufs);
+ spin_unlock_irqrestore(&acm->read_lock, flags);
+ goto next_buffer;
+
+urbs:
+ while (!list_empty(&acm->spare_read_bufs)) {
+ spin_lock_irq(&acm->read_lock);
If you have code that mixes irqsave and irq spinlocks something is wrong.
Interrupt handling code such as this can take the simplest form:
spin_lock(&lock);
spin_lock_irqsave is not wrong, just unnecessarily slow, but spin_lock_irq
is deadly in an interrupt handler or tasklet.
Regards
Oliver
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