Re: [PATCH 1/2] scsi: sas: flush destruct workqueue on device unregister
From: John Garry
Date: Wed Mar 29 2017 - 07:17:16 EST
On 29/03/2017 10:41, Johannes Thumshirn wrote:
In the advent of an SAS device unregister we have to wait for all destruct
works to be done to not accidently delay deletion of a SAS rphy or it's
children to the point when we're removing the SCSI or SAS hosts.
Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
---
drivers/scsi/libsas/sas_discover.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 60de662..75b18f1 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -382,9 +382,13 @@ void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *dev)
}
if (!test_and_set_bit(SAS_DEV_DESTROY, &dev->state)) {
+ struct sas_discovery *disc = &dev->port->disc;
+ struct sas_work *sw = &disc->disc_work[DISCE_DESTRUCT].work;
+
sas_rphy_unlink(dev->rphy);
list_move_tail(&dev->disco_list_node, &port->destroy_list);
sas_discover_event(dev->port, DISCE_DESTRUCT);
+ flush_work(&sw->work);
I quickly tested plugging out the expander and we never get past this
call to flush - a hang results:
root@(none)$ [ 243.357088] INFO: task kworker/u32:1:106 blocked for
more than 120 seconds.
[ 243.364030] Not tainted 4.11.0-rc1-13687-g2562e6a-dirty #1388
[ 243.370282] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[ 243.378086] kworker/u32:1 D 0 106 2 0x00000000
[ 243.383566] Workqueue: scsi_wq_0 sas_phye_loss_of_signal
[ 243.388863] Call trace:
[ 243.391314] [<ffff000008085d70>] __switch_to+0xa4/0xb0
[ 243.396442] [<ffff0000088f1134>] __schedule+0x1b4/0x5d0
[ 243.401654] [<ffff0000088f1588>] schedule+0x38/0x9c
[ 243.406520] [<ffff0000088f4540>] schedule_timeout+0x194/0x294
[ 243.412249] [<ffff0000088f202c>] wait_for_common+0xb0/0x144
[ 243.417805] [<ffff0000088f20d4>] wait_for_completion+0x14/0x1c
[ 243.423623] [<ffff0000080d5bd4>] flush_work+0xe0/0x1a8
[ 243.428747] [<ffff000008598158>] sas_unregister_dev+0xf8/0x110
[ 243.434563] [<ffff000008598304>] sas_unregister_domain_devices+0x4c/0xc8
[ 243.441242] [<ffff000008596884>] sas_deform_port+0x14c/0x15c
[ 243.446886] [<ffff000008596508>] sas_phye_loss_of_signal+0x48/0x54
[ 243.453048] [<ffff0000080d6164>] process_one_work+0x138/0x2d8
[ 243.458776] [<ffff0000080d635c>] worker_thread+0x58/0x424
[ 243.464161] [<ffff0000080dc16c>] kthread+0xf4/0x120
[ 243.469024] [<ffff0000080836c0>] ret_from_fork+0x10/0x50
[ 364.189094] INFO: task kworker/u32:1:106 blocked for more than 120
seconds.
[ 364.196035] Not tainted 4.11.0-rc1-13687-g2562e6a-dirty #1388
[ 364.202281] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[ 364.210085] kworker/u32:1 D 0 106 2 0x00000000
[ 364.215558] Workqueue: scsi_wq_0 sas_phye_loss_of_signal
[ 364.220855] Call trace:
[ 364.223303] [<ffff000008085d70>] __switch_to+0xa4/0xb0
[ 364.228428] [<ffff0000088f1134>] __schedule+0x1b4/0x5d0
[ 364.233640] [<ffff0000088f1588>] schedule+0x38/0x9c
[ 364.238506] [<ffff0000088f4540>] schedule_timeout+0x194/0x294
[ 364.244237] [<ffff0000088f202c>] wait_for_common+0xb0/0x144
[ 364.249793] [<ffff0000088f20d4>] wait_for_completion+0x14/0x1c
[ 364.255610] [<ffff0000080d5bd4>] flush_work+0xe0/0x1a8
[ 364.260736] [<ffff000008598158>] sas_unregister_dev+0xf8/0x110
[ 364.266551] [<ffff000008598304>] sas_unregister_domain_devices+0x4c/0xc8
[ 364.273230] [<ffff000008596884>] sas_deform_port+0x14c/0x15c
[ 364.278872] [<ffff000008596508>] sas_phye_loss_of_signal+0x48/0x54
[ 364.285034] [<ffff0000080d6164>] process_one_work+0x138/0x2d8
[ 364.290763] [<ffff0000080d635c>] worker_thread+0x58/0x424
[ 364.296147] [<ffff0000080dc16c>] kthread+0xf4/0x120
[ 364.301013] [<ffff0000080836c0>] ret_from_fork+0x10/0x50
Is the issue that we are trying to flush the queue when we are working
in the same queue context?
Thanks,
John
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