linux-kernel - Re: [PATCH 1/3] scsi: qla2xxx: Drop starvation counter on success

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Message-ID: <ee878956-852b-4be6-b7f9-94cdea5e94dd@suse.com>
Date: Wed, 9 Oct 2024 08:30:29 +0200
From: Hannes Reinecke <hare@...e.com>
To: Anastasia Kovaleva <a.kovaleva@...ro.com>, target-devel@...r.kernel.org
Cc: njavali@...vell.com, GR-QLogic-Storage-Upstream@...vell.com,
 James.Bottomley@...senPartnership.com, martin.petersen@...cle.com,
 bvanassche@....org, quinn.tran@...ium.com, nab@...ux-iscsi.org,
 himanshu.madhani@...ium.com, linux-scsi@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux@...ro.com
Subject: Re: [PATCH 1/3] scsi: qla2xxx: Drop starvation counter on success

On 10/8/24 15:24, Anastasia Kovaleva wrote:
> Long-lived sessions under high load can accumulate a starvation counter,
> and the current implementation does not allow this counter to be reset
> during an active session.
> 
> If HBA sends correct ATIO IOCB, then it has enough resources to process
> commands and we should not call ISP recovery.
> 
> Cc: stable@...r.kernel.org
> Fixes: ead038556f64 ("qla2xxx: Add Dual mode support in the driver")
> Signed-off-by: Anastasia Kovaleva <a.kovaleva@...ro.com>
> Reviewed-by: Dmitry Bogdanov <d.bogdanov@...ro.com>
> ---
>   drivers/scsi/qla2xxx/qla_isr.c    |  4 ++++
>   drivers/scsi/qla2xxx/qla_target.c | 11 +++++++++++
>   2 files changed, 15 insertions(+)
> 
> diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
> index fe98c76e9be3..5234ce0985e0 100644
> --- a/drivers/scsi/qla2xxx/qla_isr.c
> +++ b/drivers/scsi/qla2xxx/qla_isr.c
> @@ -1959,6 +1959,10 @@ qla2x00_async_event(scsi_qla_host_t *vha, struct rsp_que *rsp, uint16_t *mb)
>   		ql_dbg(ql_dbg_async, vha, 0x5091, "Transceiver Removal\n");
>   		break;
>   
> +	case MBA_REJECTED_FCP_CMD:
> +		ql_dbg(ql_dbg_async, vha, 0x5092, "LS_RJT was sent. No resources to process the ELS request.\n");
> +		break;
> +
>   	default:
>   		ql_dbg(ql_dbg_async, vha, 0x5057,
>   		    "Unknown AEN:%04x %04x %04x %04x\n",
> diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
> index d7551b1443e4..bc7feef6ee79 100644
> --- a/drivers/scsi/qla2xxx/qla_target.c
> +++ b/drivers/scsi/qla2xxx/qla_target.c
> @@ -6801,6 +6801,7 @@ qlt_24xx_process_atio_queue(struct scsi_qla_host *vha, uint8_t ha_locked)
>   	struct qla_hw_data *ha = vha->hw;
>   	struct atio_from_isp *pkt;
>   	int cnt, i;
> +	unsigned long flags = 0;
>   
>   	if (!ha->flags.fw_started)
>   		return;
> @@ -6826,6 +6827,16 @@ qlt_24xx_process_atio_queue(struct scsi_qla_host *vha, uint8_t ha_locked)
>   			qlt_send_term_exchange(ha->base_qpair, NULL, pkt,
>   			    ha_locked, 0);
>   		} else {
> +			/*
> +			 * If we get correct ATIO, then HBA had enough memory
> +			 * to proceed without reset.
> +			 */
> +			if (!ha_locked)
> +				spin_lock_irqsave(&ha->hardware_lock, flags);
> +			vha->hw->exch_starvation = 0;
> +			if (!ha_locked)
> +				spin_unlock_irqrestore(&ha->hardware_lock, flags);
> +
>   			qlt_24xx_atio_pkt_all_vps(vha,
>   			    (struct atio_from_isp *)pkt, ha_locked);
>   		}

Why not just 'WRITE_ONCE()' and drop the spinlock?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@...e.com                               +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich