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

[Vasu Dev <vasu.dev-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

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-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org>
> CC: linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> CC: Robert Love <robert.w.love-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> CC: Vasu Dev <vasu.dev-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
>  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-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> 


>  		spin_lock_irqsave(shost->host_lock, flags);
>  		rport->flags &= ~FC_RPORT_DEVLOSS_PENDING;
>  	}