From: John Garry <john.garry@huawei.com>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>,
Logan Gunthorpe <logang@deltatee.com>,
<linux-scsi@vger.kernel.org>, <linux-block@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
Intel SCU Linux support <intel-linux-scu@intel.com>,
Artur Paszkiewicz <artur.paszkiewicz@intel.com>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
Jens Axboe <axboe@kernel.dk>, Jeff Moyer <jmoyer@redhat.com>,
chenxiang <chenxiang66@hisilicon.com>
Subject: Re: [PATCH] scsi: isci: initialize shost fully before calling scsi_add_host()
Date: Mon, 14 Jan 2019 12:10:23 +0000 [thread overview]
Message-ID: <0ffaf166-c7e5-b135-fdc5-bcac24148e62@huawei.com> (raw)
In-Reply-To: <yq1lg3qy578.fsf@oracle.com>
On 12/01/2019 02:34, Martin K. Petersen wrote:
>
> John,
>
>> So how about just drop these APIs and let the user set the shost
>> protection parameters directly, like other shost parameters,
>
> The protection interfaces here obviously predate the block layer
> allocation changes that made this particular issue pop up.
>
>> which should make it a bit clearer when these should be set,
>> i.e. before scsi_add_host()?
>
> In general, I am not so keen on the somewhat messy intersection between
> the host parameters and the host template. The static host templates
> made lots of sense in the days of Seagate ST01 and fixed hardware
> capabilities. But reality is that most modern controllers have to query
> firmware interfaces to figure out what their actual capabilities are.
Hi Martin,
I am not suggested setting the parameters via scsi host template, but
rather dynamically (as we currently do) but just drop the set helper
functions, like:
shost->max_channel = 1;
shost->max_cmd_len = 16;
...
if (hisi_hba->prot_mask) {
dev_info(dev, "Registering for DIF/DIX prot_mask=0x%x\n",
prot_mask);
- scsi_host_set_prot(hisi_hba->shost, prot_mask);
+ shost->prot_capabilities = prot_mask;
}
rc = scsi_add_host(shost, dev);
if (rc)
goto err_out_ha;
rc = sas_register_ha(sha);
if (rc)
goto err_out_register_ha;
I find that it is not crystal clear when scsi_host_set_prot() and
scsi_host_set_guard() should be called, but not so for setting the shost
parameters directly, which is common.
>
> So in this case I think that accessor functions are actually better
> because they allow us to print a big fat warning when you twiddle
> something you shouldn't post-initialization. So that's something I think
> we could--and should--improve.
>
Sure, this is an alternative, but I would rather make it obvious when
these parameters should be set so that this would not be required.
Thanks,
John
next prev parent reply other threads:[~2019-01-14 12:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-08 20:50 [PATCH] scsi: isci: initialize shost fully before calling scsi_add_host() Logan Gunthorpe
2019-01-08 21:25 ` Jeff Moyer
2019-01-08 21:30 ` Jens Axboe
2019-01-09 3:29 ` Martin K. Petersen
2019-01-09 18:41 ` Christoph Hellwig
2019-01-10 9:11 ` John Garry
2019-01-12 2:34 ` Martin K. Petersen
2019-01-14 12:10 ` John Garry [this message]
2019-01-16 2:54 ` Martin K. Petersen
2019-01-16 14:44 ` John Garry
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