Messages in this thread | | | Date | Fri, 6 Mar 2009 15:56:23 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/2] resubmit cciss: kernel thread to detect changes on MSA2012 |
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On Fri, 6 Mar 2009 17:29:18 -0600 "Mike Miller (OS Dev)" <mikem@beardog.cca.cpqcorp.net> 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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