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[SCSI] zfcp: Fix hang when offlining device with offline chpid

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Running chchp --vary 0 and chccwdev -d on a FCP device with scsi
devices attached can lead to this thread hanging:

================================================================
STACK TRACE FOR TASK: 0x2fbfcc00 (kslowcrw)

 STACK:
 0 schedule+1136 [0x45f99c]
 1 schedule_timeout+534 [0x46054e]
 2 wait_for_common+374 [0x45f442]
 3 blk_execute_rq+160 [0x217a2c]
 4 scsi_execute+278 [0x26daf2]
 5 scsi_execute_req+150 [0x26dc86]
 6 sd_sync_cache+138 [0x28460a]
 7 sd_shutdown+130 [0x28486a]
 8 sd_remove+104 [0x284c84]
 9 __device_release_driver+152 [0x257430]
10 device_release_driver+56 [0x2575c8]
11 bus_remove_device+214 [0x25672a]
12 device_del+352 [0x25456c]
13 __scsi_remove_device+108 [0x272630]
14 scsi_remove_device+66 [0x2726ba]
15 zfcp_ccw_remove+824 [0x335558]
16 ccw_device_remove+62 [0x2b3f2a]
17 __device_release_driver+152 [0x257430]
18 device_release_driver+56 [0x2575c8]
19 bus_remove_device+214 [0x25672a]
20 device_del+352 [0x25456c]
21 ccw_device_unregister+92 [0x2b48c4]
22 io_subchannel_remove+108 [0x2b4950]
23 css_remove+62 [0x2af7ee]
24 __device_release_driver+152 [0x257430]
25 device_release_driver+56 [0x2575c8]
26 bus_remove_device+214 [0x25672a]
27 device_del+352 [0x25456c]
28 device_unregister+38 [0x25464a]
29 css_sch_device_unregister+68 [0x2af97c]
30 ccw_device_call_sch_unregister+78 [0x2b581e]
31 worker_thread+604 [0x69eb0]
32 kthread+154 [0x6ff42]
33 kernel_thread_starter+6 [0x1c952]
================================================================

The problem is that the chchp --vary 0 leads to zfcp first calling
fc_remote_port_delete which blocks all scsi devices on the remote
port. Calling scsi_remove_device later lets the sd driver issue a
SYNCHRONIZE_CACHE command. This command stays on the "stopped" request
requeue because the SCSI device is blocked. Fix this by first removing
the scsi and fc hosts which removes all scsi devices and do not use
scsi_remove_device.

Reviewed-by: Felix Beck <felix.beck@de.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
This commit is contained in:
Christof Schmitt 2009-09-24 10:23:25 +02:00 committed by James Bottomley
parent f45a54214a
commit d74cf7c3e9
2 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/s390/scsi/zfcp_aux.c
View File

@ -604,7 +604,6 @@ void zfcp_adapter_dequeue(struct zfcp_adapter *adapter)
cancel_work_sync(&adapter->stat_work);
zfcp_fc_wka_ports_force_offline(adapter->gs);
zfcp_adapter_scsi_unregister(adapter);
sysfs_remove_group(&adapter->ccw_device->dev.kobj,
&zfcp_sysfs_adapter_attrs);
dev_set_drvdata(&adapter->ccw_device->dev, NULL);

9
drivers/s390/scsi/zfcp_ccw.c
View File

@ -107,6 +107,10 @@ static void zfcp_ccw_remove(struct ccw_device *ccw_device)
cancel_work_sync(&adapter->scan_work);
mutex_lock(&zfcp_data.config_mutex);
/* this also removes the scsi devices, so call it first */
zfcp_adapter_scsi_unregister(adapter);
write_lock_irq(&zfcp_data.config_lock);
list_for_each_entry_safe(port, p, &adapter->port_list_head, list) {
list_for_each_entry_safe(unit, u, &port->unit_list_head, list) {
@ -121,11 +125,8 @@ static void zfcp_ccw_remove(struct ccw_device *ccw_device)
write_unlock_irq(&zfcp_data.config_lock);
list_for_each_entry_safe(port, p, &port_remove_lh, list) {
list_for_each_entry_safe(unit, u, &unit_remove_lh, list) {
if (unit->device)
scsi_remove_device(unit->device);
list_for_each_entry_safe(unit, u, &unit_remove_lh, list)
zfcp_unit_dequeue(unit);
}
zfcp_port_dequeue(port);
}
wait_event(adapter->remove_wq, atomic_read(&adapter->refcount) == 0);