Re: [PATCH v7] scsi:iscsi: Fix multiple iscsi session unbind event sent to userspace

[Mike Christie <michael.christie@oracle.com>]

On 11/25/22 7:07 PM, Wenchao Hao wrote:
> I found an issue that kernel would send ISCSI_KEVENT_UNBIND_SESSION
> for multiple times which should be fixed.
> 
> This patch introduce target_state in iscsi_cls_session to make
> sure session would send only one ISCSI_KEVENT_UNBIND_SESSION.
> 
> But this would break issue fixed in commit 13e60d3ba287 ("scsi: iscsi:
> Report unbind session event when the target has been removed"). The issue
> is iscsid died for any reason after it send unbind session to kernel, once
> iscsid restart again, it loss kernel's ISCSI_KEVENT_UNBIND_SESSION event.
> 
> Now kernel think iscsi_cls_session has already sent an
> ISCSI_KEVENT_UNBIND_SESSION event and would not send it any more. Which
> would cause userspace unable to logout. Actually the session is in
> invalid state(it's target_id is INVALID), iscsid should not sync this
> session in it's restart.
> 
> So we need to check session's target state during iscsid restart,
> if session is in unbound state, do not sync this session and perform
> session teardown. It's reasonable because once a session is unbound, we
> can not recover it any more(mainly because it's target id is INVALID)
> 
> V7:
> - Define target state to string map and refer this map directly
> - Cleanup __iscsi_unbind_session, drop check for session's
>   target_id == ISCSI_MAX_TARGET since it can be handled by target_state
> 
> V6:
> - Set target state to ALLOCATED in iscsi_add_session
> - Rename state BOUND to SCANNED
> - Make iscsi_session_target_state_name() more efficient
> 
> V5:
> - Add ISCSI_SESSION_TARGET_ALLOCATED to indicate the session's
>   target has been allocated but not scanned yet. We should
>   sync this session and scan this session when iscsid restarted.
> 
> V4:
> - Move debug print out of spinlock critical section
> 
> V3:
> - Make target bind state to a state kind rather than a bool.
> 
> V2:
> - Using target_unbound rather than state to indicate session has been
>   unbound
> 
> Signed-off-by: Wenchao Hao <haowenchao@huawei.com>

Reviewed-by: Mike Christie <michael.christie@oracle.com>