Hi Nick et al,
I'm having a "interesting" problem with the kernel's iSCSI target and
could use a debug hint.
My target uses an iblock backstore on a dm-linear target. When I now
get I/O form the initiator (I used a simple dd if=/dev/sda
of=/dev/null) and call 'dmsetup suspend $backstore' it'll take about
15 seconds for the iscsi_ttx kernel thread to disapear, the iscsi_trx
and iscsi_np threads are hanging in 'D'.
>From iscsi_trx's stack I see it's waiting in
__transport_wait_for_tasks(). The last thing I see in dmesg is the
'ABORT_TASK: Found referenced %s task_tag: %llu' printk but the
'ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for ref_tag: %llu" printk
is missing from core_tmr_abort_task(). As there's a
transport_wait_for_tasks() call in between I _think_ it is stuck in
aborting this one task and none of the
complete(se_cmd->t_transport_stop_comp) callers is called. What
puzzels me a bit is that right after transport_wait_for_tasks() in
core_tmr_abort_task() there's a call to transport_cmd_finish_abort()
which in turn calls transport_cmd_check_stop_to_fabric() ->
transport_cmd_check_stop() ->
complete_all(&cmd->t_transport_stop_comp).
Doing
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2739,7 +2739,7 @@ __transport_wait_for_tasks(struct se_cmd
spin_unlock_irqrestore(&cmd->t_state_lock, *flags);
- wait_for_completion(&cmd->t_transport_stop_comp);
+ wait_for_completion_interruptible(&cmd->t_transport_stop_comp, 5 * HZ);
spin_lock_irqsave(&cmd->t_state_lock, *flags);
cmd->transport_state &= ~(CMD_T_ACTIVE | CMD_T_STOP);
"resolves" the bug, but I don't think this is correct.
This is all easily reproducible with v4.8-rc4 in qemu (for instance).
Any advice is aprechiated.
Thanks in advance,
Johannes
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Johannes Thumshirn Storage
jthumshirn@xxxxxxx +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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HRB 21284 (AG Nürnberg)
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