From: Steffen Maier <maier@xxxxxxxxxxxxx>
commit 819732be9fea728623e1ed84eba28def7384ad1f upstream.
v2.6.27 commit cc8c282963bd ("[SCSI] zfcp: Automatically attach remote
ports") introduced zfcp automatic port scan.
Before that, the user had to use the sysfs attribute "port_add" of an FCP
device (adapter) to add and open remote (target) ports, even for the remote
peer port in point-to-point topology. That code path did a proper port open
recovery trigger taking the erp_lock.
Since above commit, a new helper function zfcp_erp_open_ptp_port()
performed an UNlocked port open recovery trigger. This can race with other
parallel recovery triggers. In zfcp_erp_action_enqueue() this could corrupt
e.g. adapter->erp_total_count or adapter->erp_ready_head.
As already found for fabric topology in v4.17 commit fa89adba1941 ("scsi:
zfcp: fix infinite iteration on ERP ready list"), there was an endless loop
during tracing of rport (un)block. A subsequent v4.18 commit 9e156c54ace3
("scsi: zfcp: assert that the ERP lock is held when tracing a recovery
trigger") introduced a lockdep assertion for that case.
As a side effect, that lockdep assertion now uncovered the unlocked code
path for PtP. It is from within an adapter ERP action:
zfcp_erp_strategy[1479] intentionally DROPs erp lock around
zfcp_erp_strategy_do_action()
zfcp_erp_strategy_do_action[1441] NO erp lock
zfcp_erp_adapter_strategy[876] NO erp lock
zfcp_erp_adapter_strategy_open[855] NO erp lock
zfcp_erp_adapter_strategy_open_fsf[806]NO erp lock
zfcp_erp_adapter_strat_fsf_xconf[772] erp lock only around
zfcp_erp_action_to_running(),
BUT *_not_* around
zfcp_erp_enqueue_ptp_port()
zfcp_erp_enqueue_ptp_port[728] BUG: *_not_* taking erp lock
_zfcp_erp_port_reopen[432] assumes to be called with erp lock
zfcp_erp_action_enqueue[314] assumes to be called with erp lock
zfcp_dbf_rec_trig[288] _checks_ to be called with erp lock:
lockdep_assert_held(&adapter->erp_lock);
It causes the following lockdep warning:
WARNING: CPU: 2 PID: 775 at drivers/s390/scsi/zfcp_dbf.c:288
zfcp_dbf_rec_trig+0x16a/0x188
no locks held by zfcperp0.0.17c0/775.
Fix this by using the proper locked recovery trigger helper function.
Link: https://lore.kernel.org/r/20200312174505.51294-2-maier@xxxxxxxxxxxxx
Fixes: cc8c282963bd ("[SCSI] zfcp: Automatically attach remote ports")
Cc: <stable@xxxxxxxxxxxxxxx> #v2.6.27+
Reviewed-by: Jens Remus <jremus@xxxxxxxxxxxxx>
Reviewed-by: Benjamin Block <bblock@xxxxxxxxxxxxx>
Signed-off-by: Steffen Maier <maier@xxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/s390/scsi/zfcp_erp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -747,7 +747,7 @@ static void zfcp_erp_enqueue_ptp_port(st
adapter->peer_d_id);
if (IS_ERR(port)) /* error or port already attached */
return;
- _zfcp_erp_port_reopen(port, 0, "ereptp1");
+ zfcp_erp_port_reopen(port, 0, "ereptp1");
}
static int zfcp_erp_adapter_strat_fsf_xconf(struct zfcp_erp_action *erp_action)
