Re: Fedora bug report - cdc-acm spinlock recursion

On Fri, 12 Jan 2007 22:28:23 +0100, Oliver Neukum <[email protected]> wrote:
> Am Freitag, 12. Januar 2007 21:56 schrieb Pete Zaitcev:

> > Another one of those which I dump on the list in case anyone is interested.
> > I was going to look at it "after Australia" some time.
> > 
> > https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=222083
> > 222083: USB spinlock recursion bug in acm_read_bulk
> 
> Very odd. The driver does not have that many spinlocks. Does Redhat
> apply any patches to cdc-acm?

No, we don't have any extra patches, but never mind. The requestor runs
a 2.6.18 kernel, so I am pretty sure that it's this:

--- linux-2.6.18-10.el5/drivers/usb/class/cdc-acm.c     2006-09-19 20:42:06.0000
00000 -0700
+++ linux-2.6.20-1.2923.fc6/drivers/usb/class/cdc-acm.c 2007-02-04 10:44:54.0000
00000 -0800
@@ -333,15 +333,15 @@ static void acm_rx_tasklet(unsigned long
                return;
 
 next_buffer:
-       spin_lock(&acm->read_lock);
+       spin_lock_irqsave(&acm->read_lock, flags);
        if (list_empty(&acm->filled_read_bufs)) {
-               spin_unlock(&acm->read_lock);
+               spin_unlock_irqrestore(&acm->read_lock, flags);
                goto urbs;
        }
.............

Sorry for the trouble.
-- Pete

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