From d74cf7c3e9c4a6a659e0442aafb550b162d15e72 Mon Sep 17 00:00:00 2001 From: Christof Schmitt Date: Thu, 24 Sep 2009 10:23:25 +0200 Subject: [PATCH] [SCSI] zfcp: Fix hang when offlining device with offline chpid 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 Signed-off-by: Christof Schmitt Signed-off-by: James Bottomley --- drivers/s390/scsi/zfcp_aux.c | 1 - drivers/s390/scsi/zfcp_ccw.c | 9 +++++---- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c index 5dcac24a7a1b..0f79f3af4f54 100644 --- a/drivers/s390/scsi/zfcp_aux.c +++ b/drivers/s390/scsi/zfcp_aux.c @@ -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); diff --git a/drivers/s390/scsi/zfcp_ccw.c b/drivers/s390/scsi/zfcp_ccw.c index 9fe32f7ec8d2..e08339428ecf 100644 --- a/drivers/s390/scsi/zfcp_ccw.c +++ b/drivers/s390/scsi/zfcp_ccw.c @@ -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);