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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Roman Bolshakov <r.bolshakov@yadro.com>,
        Dmitry Bogdanov <d.bogdanov@yadro.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 22/84] scsi: target: qla2xxx: Wait for stop_phase1 at WWN removal
Date:   Mon, 14 Jun 2021 12:27:00 +0200
Message-Id: <20210614102647.116379560@linuxfoundation.org>
In-Reply-To: <20210614102646.341387537@linuxfoundation.org>
References: <20210614102646.341387537@linuxfoundation.org>
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From: Dmitry Bogdanov <d.bogdanov@yadro.com>

[ Upstream commit 2ef7665dfd88830f15415ba007c7c9a46be7acd8 ]

Target de-configuration panics at high CPU load because TPGT and WWPN can
be removed on separate threads.

TPGT removal requests a reset HBA on a separate thread and waits for reset
complete (phase1). Due to high CPU load that HBA reset can be delayed for
some time.

WWPN removal does qlt_stop_phase2(). There it is believed that phase1 has
already completed and thus tgt.tgt_ops is subsequently cleared. However,
tgt.tgt_ops is needed to process incoming traffic and therefore this will
cause one of the following panics:

NIP qlt_reset+0x7c/0x220 [qla2xxx]
LR  qlt_reset+0x68/0x220 [qla2xxx]
Call Trace:
0xc000003ffff63a78 (unreliable)
qlt_handle_imm_notify+0x800/0x10c0 [qla2xxx]
qlt_24xx_atio_pkt+0x208/0x590 [qla2xxx]
qlt_24xx_process_atio_queue+0x33c/0x7a0 [qla2xxx]
qla83xx_msix_atio_q+0x54/0x90 [qla2xxx]

or

NIP qlt_24xx_handle_abts+0xd0/0x2a0 [qla2xxx]
LR  qlt_24xx_handle_abts+0xb4/0x2a0 [qla2xxx]
Call Trace:
qlt_24xx_handle_abts+0x90/0x2a0 [qla2xxx] (unreliable)
qlt_24xx_process_atio_queue+0x500/0x7a0 [qla2xxx]
qla83xx_msix_atio_q+0x54/0x90 [qla2xxx]

or

NIP qlt_create_sess+0x90/0x4e0 [qla2xxx]
LR  qla24xx_do_nack_work+0xa8/0x180 [qla2xxx]
Call Trace:
0xc0000000348fba30 (unreliable)
qla24xx_do_nack_work+0xa8/0x180 [qla2xxx]
qla2x00_do_work+0x674/0xbf0 [qla2xxx]
qla2x00_iocb_work_fn

The patch fixes the issue by serializing qlt_stop_phase1() and
qlt_stop_phase2() functions to make WWPN removal wait for phase1
completion.

Link: https://lore.kernel.org/r/20210415203554.27890-1-d.bogdanov@yadro.com
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/scsi/qla2xxx/qla_target.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index 509539ec58e9..57068e2faef5 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -1559,10 +1559,12 @@ void qlt_stop_phase2(struct qla_tgt *tgt)
 		return;
 	}
 
+	mutex_lock(&tgt->ha->optrom_mutex);
 	mutex_lock(&vha->vha_tgt.tgt_mutex);
 	tgt->tgt_stop = 0;
 	tgt->tgt_stopped = 1;
 	mutex_unlock(&vha->vha_tgt.tgt_mutex);
+	mutex_unlock(&tgt->ha->optrom_mutex);
 
 	ql_dbg(ql_dbg_tgt_mgt, vha, 0xf00c, "Stop of tgt %p finished\n",
 	    tgt);
-- 
2.30.2