Re: waiting process in procfs read

[Nish Aravamudan <nish.aravamudan@gmail.com>]

On 8/26/05, Nish Aravamudan <nish.aravamudan@gmail.com> wrote:
> On 8/26/05, Richard Stover <richard@ucolick.org> wrote:
> > I submitted this as a bugzilla kernel bug report but was directed here.
> > Perhaps someone can help me.
> >
> > I have a device driver developed with 2.4 kernels. I've ported
> > it to the 2.6 kernel (FC3) and it all works fine except for one
> > aspect of procfs.
> 
> <snip>
> 
> > THE PROBLEM: In FC3 (2.6.11-13_FC3) the reading process blocks but it never
> > wakes up.
> 
> <snip>
> 
> >        if (offset == 0) {
> >
> >            printk("####%s waiting event %x\n",__FUNCTION__,
> >                (unsigned int)&dev->read_proc_wait);
> >
> >            wait_event_interruptible(dev->read_proc_wait,(offset != 0));
> >            printk("####%s WOKE UP\n",__FUNCTION__);
> 
> <snip>
> 
> > /*      Wake up anyone waiting on reading /proc/readXw                  */
> >        printk(KERN_INFO "#### waking up anyone waiting on read_proc_wait event %x\n",
> >                (unsigned int)&dev->read_proc_wait);
> >
> >        wake_up_interruptible(&dev->read_proc_wait);
> 
> Your symptoms indicate to me that the "event" in
> wait_event_interruptible() has not been satisifed, and thus the
> (potentially) infinite loop in wait_event_interruptible() is
> continuing, e.g. event still is 0. A signal (as you've specified

::sigh::, offset still is 0, not event :)

Thanks,
Nish
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