linux-kernel - Re: [PATCH 1/6] scsi: libsas: Add sas_task_find

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Date:   Wed, 28 Sep 2022 14:28:57 +0000
From:   Johannes Thumshirn <Johannes.Thumshirn@....com>
To:     John Garry <john.garry@...wei.com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "jinpu.wang@...ud.ionos.com" <jinpu.wang@...ud.ionos.com>,
        Damien Le Moal <Damien.LeMoal@....com>
CC:     "hare@...e.de" <hare@...e.de>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxarm@...wei.com" <linuxarm@...wei.com>,
        "ipylypiv@...gle.com" <ipylypiv@...gle.com>,
        "changyuanl@...gle.com" <changyuanl@...gle.com>,
        "hch@....de" <hch@....de>
Subject: Re: [PATCH 1/6] scsi: libsas: Add sas_task_find_rq()

On 28.09.22 15:56, John Garry wrote:
> On 28/09/2022 14:17, Johannes Thumshirn wrote:
>>> +static inline struct request *sas_task_find_rq(struct sas_task *task)
>>> +{
>>> +	struct scsi_cmnd *scmd;
>>> +
>>> +	if (!task || !task->uldd_task)
>>> +		return NULL;
>> Is anyone actually calling sas_task_find_rq with a NULL task?
> 
> Yeah, unfortunately. An example - the only one I think - is in the 
> pm8001 driver: pm8001_ccb_alloc() function which takes a task pointer 
> which may be NULL, and this function calls sas_task_find_rq()
> 
>> That doesn't make a lot of sense from an API POV for me, having
>> the only argument allowed to be NULL (and not being a *free()
>> kind of function).
> 
> I suppose that I could change to only call sas_task_find_rq() for 
> non-NULL sas_task pointers (and remove the task check).

If this is done in only a few drivers I'd go that route TBH.

AFAICS hishi sas doesn't call sas_task_find_rq with a NULL task,
so it's only pm8001