From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:55322 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726328AbgCLSPi (ORCPT ); Thu, 12 Mar 2020 14:15:38 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 02CIEWDa136479 for ; Thu, 12 Mar 2020 14:15:37 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2yqt6dg1k6-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 12 Mar 2020 14:15:37 -0400 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 12 Mar 2020 17:45:19 -0000 From: Steffen Maier Subject: [PATCH 01/10] zfcp: fix missing erp_lock in port recovery trigger for point-to-point Date: Thu, 12 Mar 2020 18:44:56 +0100 In-Reply-To: <20200312174505.51294-1-maier@linux.ibm.com> References: <20200312174505.51294-1-maier@linux.ibm.com> Message-Id: <20200312174505.51294-2-maier@linux.ibm.com> Sender: linux-s390-owner@vger.kernel.org List-ID: To: "James E . J . Bottomley" , "Martin K . Petersen" Cc: linux-scsi@vger.kernel.org, linux-s390@vger.kernel.org, Benjamin Block , Heiko Carstens , Vasily Gorbik , Steffen Maier , stable@vger.kernel.org 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. Signed-off-by: Steffen Maier Fixes: cc8c282963bd ("[SCSI] zfcp: Automatically attach remote ports") Cc: #v2.6.27+ Reviewed-by: Jens Remus Reviewed-by: Benjamin Block --- drivers/s390/scsi/zfcp_erp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c index 93655b85b73f..18a6751299f9 100644 --- a/drivers/s390/scsi/zfcp_erp.c +++ b/drivers/s390/scsi/zfcp_erp.c @@ -725,7 +725,7 @@ static void zfcp_erp_enqueue_ptp_port(struct zfcp_adapter *adapter) 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 enum zfcp_erp_act_result zfcp_erp_adapter_strat_fsf_xconf( -- 2.17.1