linux-kernel - [PATCH 5.16 0892/1017] scsi: qla2xxx: Fix laggy FC remote port session recovery

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Message-Id: <20220405070420.706251110@linuxfoundation.org>
Date:   Tue,  5 Apr 2022 09:30:05 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Himanshu Madhani <himanshu.madhani@...cle.com>,
        Quinn Tran <qutran@...vell.com>,
        Nilesh Javali <njavali@...vell.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Subject: [PATCH 5.16 0892/1017] scsi: qla2xxx: Fix laggy FC remote port session recovery

From: Quinn Tran <qutran@...vell.com>

commit 713b415726f100f6644971e75ebfe1edbef1a390 upstream.

For session recovery, driver relies on the dpc thread to initiate certain
operations. The dpc thread runs exclusively without the Mailbox interface
being occupied. A recent code change for heartbeat check via mailbox cmd 0
is preventing the dpc thread from carrying out its operation. This patch
allows the higher priority error recovery to run first before running the
lower priority heartbeat check.

Link: https://lore.kernel.org/r/20220310092604.22950-9-njavali@marvell.com
Fixes: d94d8158e184 ("scsi: qla2xxx: Add heartbeat check")
Cc: stable@...r.kernel.org
Reviewed-by: Himanshu Madhani <himanshu.madhani@...cle.com>
Signed-off-by: Quinn Tran <qutran@...vell.com>
Signed-off-by: Nilesh Javali <njavali@...vell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/scsi/qla2xxx/qla_def.h |    1 +
 drivers/scsi/qla2xxx/qla_os.c  |   20 +++++++++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

--- a/drivers/scsi/qla2xxx/qla_def.h
+++ b/drivers/scsi/qla2xxx/qla_def.h
@@ -4621,6 +4621,7 @@ struct qla_hw_data {
 	struct workqueue_struct *wq;
 	struct work_struct heartbeat_work;
 	struct qlfc_fw fw_buf;
+	unsigned long last_heartbeat_run_jiffies;
 
 	/* FCP_CMND priority support */
 	struct qla_fcp_prio_cfg *fcp_prio_cfg;
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -7209,7 +7209,7 @@ skip:
 	return do_heartbeat;
 }
 
-static void qla_heart_beat(struct scsi_qla_host *vha)
+static void qla_heart_beat(struct scsi_qla_host *vha, u16 dpc_started)
 {
 	struct qla_hw_data *ha = vha->hw;
 
@@ -7219,8 +7219,19 @@ static void qla_heart_beat(struct scsi_q
 	if (vha->hw->flags.eeh_busy || qla2x00_chip_is_down(vha))
 		return;
 
-	if (qla_do_heartbeat(vha))
+	/*
+	 * dpc thread cannot run if heartbeat is running at the same time.
+	 * We also do not want to starve heartbeat task. Therefore, do
+	 * heartbeat task at least once every 5 seconds.
+	 */
+	if (dpc_started &&
+	    time_before(jiffies, ha->last_heartbeat_run_jiffies + 5 * HZ))
+		return;
+
+	if (qla_do_heartbeat(vha)) {
+		ha->last_heartbeat_run_jiffies = jiffies;
 		queue_work(ha->wq, &ha->heartbeat_work);
+	}
 }
 
 /**************************************************************************
@@ -7411,6 +7422,8 @@ qla2x00_timer(struct timer_list *t)
 		start_dpc++;
 	}
 
+	/* borrowing w to signify dpc will run */
+	w = 0;
 	/* Schedule the DPC routine if needed */
 	if ((test_bit(ISP_ABORT_NEEDED, &vha->dpc_flags) ||
 	    test_bit(LOOP_RESYNC_NEEDED, &vha->dpc_flags) ||
@@ -7443,9 +7456,10 @@ qla2x00_timer(struct timer_list *t)
 		    test_bit(RELOGIN_NEEDED, &vha->dpc_flags),
 		    test_bit(PROCESS_PUREX_IOCB, &vha->dpc_flags));
 		qla2xxx_wake_dpc(vha);
+		w = 1;
 	}
 
-	qla_heart_beat(vha);
+	qla_heart_beat(vha, w);
 
 	qla2x00_restart_timer(vha, WATCH_INTERVAL);
 }