scsi: libiscsi: Fix cmds hung when sd_shutdown

hulk inclusion
category: bugfix
bugzilla: NA
CVE: NA

https://gitee.com/src-openeuler/kernel/issues/I28N9J
---------------------------

For some reason, during reboot the system, iscsi.service failed to
logout all sessions. kernel will hang forever on its
sd_sync_cache() logic, after issuing the SYNCHRONIZE_CACHE cmd to all
still existent paths.

[ 1044.098991] reboot: Mddev shutdown finished.
[ 1044.099311] reboot: Usermodehelper disable finished.
[ 1050.611244]  connection2:0: ping timeout of 5 secs expired, recv timeout 5,
last rx 4295152378, last ping 4295153633, now 4295154944
[ 1348.599676] Call trace:
[ 1348.599887]  __switch_to+0xe8/0x150
[ 1348.600113]  __schedule+0x33c/0xa08
[ 1348.600372]  schedule+0x2c/0x88
[ 1348.600567]  schedule_timeout+0x184/0x3a8
[ 1348.600820]  io_schedule_timeout+0x28/0x48
[ 1348.601089]  wait_for_common_io.constprop.2+0x168/0x258
[ 1348.601425]  wait_for_completion_io_timeout+0x28/0x38
[ 1348.601762]  blk_execute_rq+0x98/0xd8
[ 1348.602006]  __scsi_execute+0xe0/0x1e8
[ 1348.602262]  sd_sync_cache+0xd0/0x220 [sd_mod]
[ 1348.602551]  sd_shutdown+0x6c/0xf8 [sd_mod]
[ 1348.602826]  device_shutdown+0x13c/0x250
[ 1348.603078]  kernel_restart_prepare+0x5c/0x68
[ 1348.603400]  kernel_restart+0x20/0x98
[ 1348.603683]  __se_sys_reboot+0x214/0x260
[ 1348.603987]  __arm64_sys_reboot+0x24/0x30
[ 1348.604300]  el0_svc_common+0x80/0x1b8
[ 1348.604590]  el0_svc_handler+0x78/0xe0
[ 1348.604877]  el0_svc+0x10/0x260

d7549412 (scsi: libiscsi: Allow sd_shutdown on bad transport) Once
solved this problem. The iscsi_eh_cmd_timed_out() function add system_state
judgment, and will return BLK_EH_DONE and mark the result as
DID_NO_CONNECT when system_state is not SYSTEM_RUNNING,
To tell upper layers that the command was handled during
the transport layer error handler helper.

The scsi Mid Layer timeout handler function(scsi_times_out) will be
abort the cmd if the scsi LLD timeout handler return BLK_EH_DONE.
if abort cmd failed, will enter scsi EH logic.

Scsi EH will do reset target logic, if reset target failed, Will
call iscsi_eh_session_reset() function to drop the session.

The iscsi_eh_session_reset function will wait for a relogin,
session termination from userspace, or a recovery/replacement timeout.
But at this time, the app iscsid has exited, and the session was marked as
ISCSI_STATE_FAILED, So the SCSI EH process will never be
scheduled back again.

PID: 9123   TASK: ffff80020c1b4d80  CPU: 3   COMMAND: "scsi_eh_2"
 #0 [ffff00008632bb70] __switch_to at ffff000080088738
 #1 [ffff00008632bb90] __schedule at ffff000080a00480
 #2 [ffff00008632bc20] schedule at ffff000080a00b58
 #3 [ffff00008632bc30] iscsi_eh_session_reset at ffff000000d1ab9c [libiscsi]
 #4 [ffff00008632bcb0] iscsi_eh_recover_target at ffff000000d1d1fc [libiscsi]
 #5 [ffff00008632bd00] scsi_try_target_reset at ffff0000806f0bac
 #6 [ffff00008632bd30] scsi_eh_ready_devs at ffff0000806f2724
 #7 [ffff00008632bde0] scsi_error_handler at ffff0000806f41d4
 #8 [ffff00008632be70] kthread at ffff000080119ae0
Reported-by: NTianxiong Lu <lutianxiong@huawei.com>
Signed-off-by: NWu Bo <wubo40@huawei.com>
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/scsi/libiscsi.c

@@ -2441,7 +2441,17 @@ int iscsi_eh_session_reset(struct scsi_cmnd *sc)
 
 	mutex_lock(&session->eh_mutex);
 	spin_lock_bh(&session->frwd_lock);
-	if (session->state == ISCSI_STATE_TERMINATE) {
+
+	/*
+	 * During shutdown, if session is prematurely disconnected, recovery
+	 * won't happen and there will be hung cmds. To solve this case, all
+	 * cmds would be enter scsi EH, but the EH path will wait for
+	 * wait_event_interruptible() to complete until the state of the
+	 * session is ISCSI_STATE_TERMINATE, ISCSI_STATE_LOGGED_IN or
+	 * ISCSI_STATE_RECOVERY_FAILED.
+	 */
+	if (session->state == ISCSI_STATE_TERMINATE ||
+	    unlikely(system_state != SYSTEM_RUNNING)) {
 failed:
 		ISCSI_DBG_EH(session,
 			     "failing session reset: Could not log back into "