linux-kernel - Re: [PATCH] scsi: pm80xx: Remove msleep() loop from pm8001_dev_gone

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Message-ID: <784f6b4a-7c43-4484-988e-73fad594c99d@oracle.com>
Date: Tue, 9 Jul 2024 17:09:38 +0100
From: John Garry <john.g.garry@...cle.com>
To: TJ Adams <tadamsjr@...gle.com>, Jack Wang <jinpu.wang@...ud.ionos.com>,
        "James E . J . Bottomley" <James.Bottomley@...senPartnership.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>
Cc: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Igor Pylypiv <ipylypiv@...gle.com>
Subject: Re: [PATCH] scsi: pm80xx: Remove msleep() loop from
 pm8001_dev_gone_notify()

On 09/07/2024 17:00, TJ Adams wrote:
> From: Igor Pylypiv <ipylypiv@...gle.com>
> 
> It's possible to end up in a state where pm8001_dev->running_req never
> reaches zero.

Is that a driver bug then?

> In that state we will be sleeping forever.
> 
> sas_execute_internal_abort_dev() can wait for a response for
> up to 60 seconds (3 retries x 20 seconds). 60 seconds should be enough
> for pm8001_dev->running_req to get to zero.

May I suggest you drop running_req at some stage, and use other methods 
to find how many IOs are active?

> 
> Signed-off-by: Igor Pylypiv <ipylypiv@...gle.com>
> Signed-off-by: TJ Adams <tadamsjr@...gle.com>
> ---
>   drivers/scsi/pm8001/pm8001_sas.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c
> index a5a31dfa4512..513e9a49838c 100644
> --- a/drivers/scsi/pm8001/pm8001_sas.c
> +++ b/drivers/scsi/pm8001/pm8001_sas.c
> @@ -712,8 +712,11 @@ static void pm8001_dev_gone_notify(struct domain_device *dev)
>   		if (atomic_read(&pm8001_dev->running_req)) {
>   			spin_unlock_irqrestore(&pm8001_ha->lock, flags);
>   			sas_execute_internal_abort_dev(dev, 0, NULL);
> -			while (atomic_read(&pm8001_dev->running_req))
> -				msleep(20);
> +			if (atomic_read(&pm8001_dev->running_req)) {
> +				pm8001_dbg(pm8001_ha, FAIL,
> +					   "device_id: %u: Failed to abort %d requests!\n",
> +					   device_id, atomic_read(&pm8001_dev->running_req));
> +			}
>   			spin_lock_irqsave(&pm8001_ha->lock, flags);
>   		}
>   		PM8001_CHIP_DISP->dereg_dev_req(pm8001_ha, device_id);