On Fri, 6 Mar 2009 17:29:18 -0600
"Mike Miller (OS Dev)" <mikem@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, Mar 06, 2009 at 12:24:27PM -0600, James Bottomley wrote:
> > On Fri, 2009-03-06 at 12:16 -0600, Mike Miller wrote:
> > > Patch 1 of 2
> > >
> > > This is a resubmission of yesterdays patch to detect changes on the MSA2012.
> > > I hope I've addressed all concerns. This patch rearranges some of the code
> > > so we also have coverage in the sg and the ioctl paths as well as the main
> > > data path.
> > >
> > > The MSA2012 cannot inform the driver of configuration changes since all
> > > management is out of band. This is a departure from any storage we have
> > > supported in the past. We need some way to detect changes on the topology so
> > > we implement this kernel thread. In some instances there's nothing we can do
> > > from the driver (like LUN failure) so just print out a message. In the case
> > > where logical volumes are added or deleted we call rebuild_lun_table to
> > > refreash the driver's view of the world.
> > >
> > > Please consider this for inclusion.
> >
> > I still don't quite see how the thread stops on module removal ... there
> > needs to be an explicit kthread_stop() somewhere in the clean up path.
> >
> > James
> >
> >
> This time I make a call to kthread_stop in cciss_remove_one. The driver can
> be unloaded and the thread gets cleaned up.
Please include a complete (and suitably updated) copy of the changelog
with each iteration of a patch.
> KNOWN BUG: it seems the timeout must expire before kthread_stop actually
> stops the thread. This causes the driver to hang and wait during rmmod. I've
> played around with several things but haven't found the correct way to
> address the problem. Looking at other drivers hasn't been much help. Any
> advice is greatly appreciated.
Well, wait_for_completion_timeout() is only going to return when the
timeout timed out, or someone ran complete().
> +static int scan_thread(ctlr_info_t *h)
> +{
> + int rc;
> + DECLARE_COMPLETION_ONSTACK(wait);
> + h->rescan_wait = &wait;
> +
> + while (!kthread_should_stop()) {
> + rc = wait_for_completion_timeout(&wait, 300 * HZ);
> + if (!rc)
> + continue;
> + else
> + rebuild_lun_table(h, 0);
> + }
> + return 0;
> +}
So.. we shouldn't need the timeout here at all - just use
wait_for_completion().
static int scan_thread(ctlr_info_t *h)
{
DECLARE_COMPLETION_ONSTACK(wait);
h->rescan_wait = &wait;
for ( ; ; ) {
wait_for_completion(&wait);
if (kthread_should_stop())
break;
rebuild_lun_table(h, 0);
}
return 0;
}
And on the teardown path, do
complete(...);
kthread_stop(...);
?
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