Re: [Open-FCoE] [PATCH] fc: ensure scan_work isn't active when freeing fc_rport

[Neil Horman <nhorman@tuxdriver.com>]

On Mon, Jun 09, 2014 at 11:09:43AM -0700, Vasu Dev wrote:
> On Fri, 2014-06-06 at 16:54 -0400, Neil Horman wrote:
> > On Mon, Jun 02, 2014 at 04:22:50PM -0700, Vasu Dev wrote:
> > > On Fri, 2014-05-30 at 10:59 -0400, Neil Horman wrote:
> > > > debugfs caught this:
> > > > WARNING: at lib/debugobjects.c:260 debug_print_object+0x83/0xa0()
> > > > ODEBUG: free active (active state 0) object type: work_struct
> > > > hint: fc_scsi_scan_rport+0x0/0xd0 [scsi_transport_fc]
> > > >  CPU: 1 PID: 184 Comm: kworker/1:1 Tainted: G        W
> > > > --------------   3.10.0-123.el7.x86_64.debug #1
> > > > Hardware name: HP ProLiant DL120 G7, BIOS J01 07/01/2013
> > > > Workqueue: fc_wq_5 fc_rport_final_delete [scsi_transport_fc]
> > > > Call Trace:
> > > > [<ffffffff8169efec>] dump_stack+0x19/0x1b
> > > > [<ffffffff8106cbd1>] warn_slowpath_common+0x61/0x80
> > > > [<ffffffff8106cc4c>] warn_slowpath_fmt+0x5c/0x80
> > > > [<ffffffff8133e003>] debug_print_object+0x83/0xa0
> > > > [<ffffffffa04e2f40>] ? fc_parse_wwn+0x100/0x100
> > > > 
> > > > [<ffffffff8133f23b>] debug_check_no_obj_freed+0x22b/0x270
> > > > [<ffffffffa04e127e>] ? fc_rport_dev_release+0x1e/0x30
> > > > [<ffffffff811db3e9>] kfree+0xd9/0x2d0
> > > > [<ffffffffa04e127e>] fc_rport_dev_release+0x1e/0x30
> > > > [<ffffffff81428032>] device_release+0x32/0xa0
> > > > [<ffffffff8132701e>] kobject_release+0x7e/0x1b0
> > > > [<ffffffff81326ed8>] kobject_put+0x28/0x60
> > > > [<ffffffff81428397>] put_device+0x17/0x20
> > > > [<ffffffffa04e5025>] fc_rport_final_delete+0x165/0x210
> > > > [<ffffffff810959b0>] process_one_work+0x220/0x710
> > > > [<ffffffff81095944>] ? process_one_work+0x1b4/0x710
> > > > [<ffffffff81095fbb>] worker_thread+0x11b/0x3a0
> > > > [<ffffffff81095ea0>] ? process_one_work+0x710/0x710
> > > > [<ffffffff8109e0cd>] kthread+0xed/0x100
> > > > [<ffffffff8109dfe0>] ? insert_kthread_work+0x80/0x80
> > > > [<ffffffff816b2fec>] ret_from_fork+0x7c/0xb0
> > > > [<ffffffff8109dfe0>] ? insert_kthread_work+0x80/0x80
> > > > 
> > > > Seems to be because the scan_work work_struct might be active when the housing
> > > > fc_rport struct gets freed.  Ensure that we cancel it prior to freeing the rport
> > > > 
> > > > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> > > > CC: linux-scsi@vger.kernel.org
> > > > CC: Robert Love <robert.w.love@intel.com>
> > > > CC: Vasu Dev <vasu.dev@intel.com>
> > > > ---
> > > >  drivers/scsi/scsi_transport_fc.c | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > > 
> > > > diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
> > > > index 4628fd5..5bd552c 100644
> > > > --- a/drivers/scsi/scsi_transport_fc.c
> > > > +++ b/drivers/scsi/scsi_transport_fc.c
> > > > @@ -2548,6 +2548,7 @@ fc_rport_final_delete(struct work_struct *work)
> > > >  			fc_flush_devloss(shost);
> > > >  		if (!cancel_delayed_work(&rport->dev_loss_work))
> > > >  			fc_flush_devloss(shost);
> > > > +		cancel_work_sync(&rport->scan_work);
> > > 
> > > Make sense to ensure pending work canceled, adding James Smart for his
> > > ACK as transport FC class author. 
> > > 
> > > 
> > > Reviewed-by: Vasu Dev <vasu.dev@intel.com> 
> > > 
> > Ping on this, Something just occured to me.  I was thinking (perhaps
> > erroneously) that this would go through the FCoE tree, but I don't see that
> > you've setup a tree yet vasu (and Rob's has been idle for 6 months).  Whats the
> > plan for this (and future) fcoe patchs.  Will you have a tree, or will we send
> > this through Christophs new scsi tree perhaps?
> > 
> 
> Thanks Neil for bringing this, I and Rob also had off list discussion on
> this just last week. 
> 
> Given fcoe is quite mature now and its patches volume is very low, so
> getting its kernel patches directly to scsi subsystem should work fine
> and should be okay with James or Christophs to pull into scsi subsystem
> directly once I've my non-author signoff ACK there as described in this
> announcement at http://marc.info/?l=linux-scsi&m=140050839729415&w=2 
> 
> If no alternate suggestion or objection to this then I'll formally
> announce this on fcoe mailing list.
> 
> However for any huges patches series bomb or RFCs, I'll request fcoe
> developers to send patches against scsi tree at fcoe devel list first
> and then if needed I can roll them up.
> 
> Thanks,
> Vasu
> 
Copy that Vasu, Christoph, is that ok with you?

Neil

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