Re: [PATCH v2] libsas: fix "sysfs group not found" warnings at port teardown time

Luis Henriques
2015-05-21T07:54:20Z

On Wed, May 20, 2015 at 07:00:53PM -0400, Dan Williams wrote:
> Praveen reports:
>
> After some debugging this is what I have found
>
> sas_phye_loss_of_signal gets triggered on phy_event from mvsas
> sas_phye_loss_of_signal calls sas_deform_port
> sas_deform_port posts a DISCE_DESTRUCT event (sas_unregister_domain_devices-> sas_unregister_dev)
> sas_deform_port calls sas_port_delete
> sas_port_delete calls sas_port_delete_link
> sysfs_remove_group: kobject 'port-X:Y'
> sas_port_delete calls device_del
> sysfs_remove_group: kobject 'port-X:Y'
>
> sas_destruct_devices gets triggered for the destruct event (DISCE_DESTRUCT)
> sas_destruct_devices calls sas_rphy_delete
> sas_rphy_delete calls scsi_remove_device
> scsi_remove_device calls __scsi_remove_device
> __scsi_remove_device calls bsg_unregister_queue
> bsg_unregister_queue -> device_unregister -> device_del -> sysfs_remove_group: kobject 'X:0:0:0'
>
> Since X:0:0:0 falls under port-X:Y (which got deleted during
> sas_port_delete), this call results in the warning. All the later
> warnings in the dmesg output I sent earlier are trying to delete objects
> under port-X:Y. Since port-X:Y got recursively deleted, all these calls
> result in warnings. Since, the PHY and DISC events are processed in two
> different work queues (and one triggers the other), is there any way
> other than checking if the object exists in sysfs (in device_del) before
> deleting?
>
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 6 at fs/sysfs/group.c:219 device_del+0x40/0x1c0()
> sysfs group ffffffff818b97e0 not found for kobject '2:0:4:0'
> [..]
> CPU: 2 PID: 6 Comm: kworker/u8:0 Tainted: P W O 3.16.7-ckt9-logicube-ng.3 #1
> Hardware name: To be filled by O.E.M. To be filled by O.E.M./VT6085, BIOS 4.6.5 01/23/2015
> Workqueue: scsi_wq_2 sas_destruct_devices [libsas]
> 0000000000000009 ffffffff8151cd18 ffff88011b35bcd8 ffffffff810687b7
> ffff88011a661400 ffff88011b35bd28 ffff8800c6e5e968 ffff880000028810
> ffff8800c89f2c00 ffffffff8106881c ffffffff81733b68 0000000000000028
> Call Trace:
> [<ffffffff8151cd18>] ? dump_stack+0x41/0x51
> [<ffffffff810687b7>] ? warn_slowpath_common+0x77/0x90
> [<ffffffff8106881c>] ? warn_slowpath_fmt+0x4c/0x50
> [<ffffffff813ad2d0>] ? device_del+0x40/0x1c0
> [<ffffffff813ad46a>] ? device_unregister+0x1a/0x70
> [<ffffffff812a535e>] ? bsg_unregister_queue+0x5e/0xb0
> [<ffffffffa00781a9>] ? __scsi_remove_device+0xa9/0xd0 [scsi_mod]
>
> It appears we've always been double deleting the devices below sas_port,
> but recent sysfs changes now exposes this problem. Libsas should delete
> all the devices from rphy down before deleting the parent port.
>
> Cc: <stable@vger.kernel.org>
> Reported-by: Praveen Murali <pmurali@logicube.com>
> Tested-by: Praveen Murali <pmurali@logicube.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>
> v2: drop the "---" separators that will confuse git-am. Thanks Luis!
>

Awesome, thanks a lot!

Cheers,
--
Luís

> drivers/scsi/libsas/sas_discover.c | 6 +++---
> drivers/scsi/libsas/sas_port.c | 1 -
> 2 files changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
> index 60de66252fa2..a4db770fe8b0 100644
> --- a/drivers/scsi/libsas/sas_discover.c
> +++ b/drivers/scsi/libsas/sas_discover.c
> @@ -362,11 +362,14 @@ static void sas_destruct_devices(struct work_struct *work)
> clear_bit(DISCE_DESTRUCT, &port->disc.pending);
>
> list_for_each_entry_safe(dev, n, &port->destroy_list, disco_list_node) {
> + struct sas_port *sas_port = dev_to_sas_port(dev->rphy->dev.parent);
> +
> list_del_init(&dev->disco_list_node);
>
> sas_remove_children(&dev->rphy->dev);
> sas_rphy_delete(dev->rphy);
> sas_unregister_common_dev(port, dev);
> + sas_port_delete(sas_port);
> }
> }
>
> @@ -400,9 +403,6 @@ void sas_unregister_domain_devices(struct asd_sas_port *port, int gone)
>
> list_for_each_entry_safe(dev, n, &port->disco_list, disco_list_node)
> sas_unregister_dev(port, dev);
> -
> - port->port->rphy = NULL;
> -
> }
>
> void sas_device_set_phy(struct domain_device *dev, struct sas_port *port)
> diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
> index d3c5297c6c89..9a25ae3a52a4 100644
> --- a/drivers/scsi/libsas/sas_port.c
> +++ b/drivers/scsi/libsas/sas_port.c
> @@ -219,7 +219,6 @@ void sas_deform_port(struct asd_sas_phy *phy, int gone)
>
> if (port->num_phys == 1) {
> sas_unregister_domain_devices(port, gone);
> - sas_port_delete(port->port);
> port->port = NULL;
> } else {
> sas_port_delete_phy(port->port, phy->phy);
>
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