linux-kernel - Re: [PATCH v2 2/7] scsi: libsas: only clear phy->in

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Date:   Wed, 30 Jan 2019 16:26:28 +0000
From:   John Garry <john.garry@...wei.com>
To:     Jason Yan <yanaijie@...wei.com>, <martin.petersen@...cle.com>,
        <jejb@...ux.vnet.ibm.com>
CC:     <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <zhaohongjiang@...wei.com>, <hare@...e.com>,
        <dan.j.williams@...el.com>, <jthumshirn@...e.de>, <hch@....de>,
        <huangdaode@...ilicon.com>, <chenxiang66@...ilicon.com>,
        <xiexiuqi@...wei.com>, <tj@...nel.org>, <miaoxie@...wei.com>,
        Ewan Milne <emilne@...hat.com>, Tomas Henzl <thenzl@...hat.com>
Subject: Re: [PATCH v2 2/7] scsi: libsas: only clear phy->in_shutdown after
 shutdown event done

On 30/01/2019 08:24, Jason Yan wrote:
> When the event queue is full of phy up and down events and reached the
> threshold, we will queue a shutdown-event, and set phy->in_shutdown so
> that we will not queue a shutdown-event again. But before the
> shutdown-event can be executed, every phy-down event will clear
> phy->in_shutdown and a new shutdown-event will be queued. The queue will
> be full of these shutdown-events.
>
> Fix this by only clear phy->in_shutdown in sas_phye_shutdown(), that is
> after the first shutdown-event has been executed.
>

Seems ok as a fix:
Reviewed-by: John Garry <john.garry@...wei.com>

After this fix, could we change to use a static per-PHY shutdown event 
so that we cannot re-queue it? I know that this is going against idea of 
dynamic events, but it's easier than messing with flags like this.

> Fixes: f12486e06ae8 ("scsi: libsas: shut down the PHY if events reached the threshold")
> Signed-off-by: Jason Yan <yanaijie@...wei.com>
> CC: John Garry <john.garry@...wei.com>
> CC: Johannes Thumshirn <jthumshirn@...e.de>
> CC: Ewan Milne <emilne@...hat.com>
> CC: Christoph Hellwig <hch@....de>
> CC: Tomas Henzl <thenzl@...hat.com>
> CC: Dan Williams <dan.j.williams@...el.com>
> CC: Hannes Reinecke <hare@...e.com>
> ---
>  drivers/scsi/libsas/sas_phy.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/libsas/sas_phy.c b/drivers/scsi/libsas/sas_phy.c
> index 0374243c85d0..762bb13cca74 100644
> --- a/drivers/scsi/libsas/sas_phy.c
> +++ b/drivers/scsi/libsas/sas_phy.c
> @@ -35,7 +35,6 @@ static void sas_phye_loss_of_signal(struct work_struct *work)
>  	struct asd_sas_event *ev = to_asd_sas_event(work);
>  	struct asd_sas_phy *phy = ev->phy;
>
> -	phy->in_shutdown = 0;
>  	phy->error = 0;
>  	sas_deform_port(phy, 1);
>  }
> @@ -45,7 +44,6 @@ static void sas_phye_oob_done(struct work_struct *work)
>  	struct asd_sas_event *ev = to_asd_sas_event(work);
>  	struct asd_sas_phy *phy = ev->phy;
>
> -	phy->in_shutdown = 0;
>  	phy->error = 0;
>  }
>
> @@ -127,6 +125,7 @@ static void sas_phye_shutdown(struct work_struct *work)
>  	} else
>  		pr_notice("phy%02d is not enabled, cannot shutdown\n",
>  			  phy->id);
> +	phy->in_shutdown = 0;
>  }
>
>  /* ---------- Phy class registration ---------- */
>