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From: Bart Van Assche <bvanassche@acm.org>
To: Christoph Hellwig <hch@infradead.org>,
	James Bottomley <jejb@linux.ibm.com>
Cc: daejun7.park@samsung.com, ALIM AKHTAR <alim.akhtar@samsung.com>,
	"avri.altman@wdc.com" <avri.altman@wdc.com>,
	"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
	"huobean@gmail.com" <huobean@gmail.com>,
	Keoseong Park <keosung.park@samsung.com>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] scsi: ufs: Fix proper API to send HPB pre-request
Date: Thu, 28 Oct 2021 10:07:52 -0700	[thread overview]
Message-ID: <54b45df9-9339-c69d-73b5-9c293449b849@acm.org> (raw)
In-Reply-To: <YXrBTHmu/fiAaZH5@infradead.org>

On 10/28/21 8:27 AM, Christoph Hellwig wrote:
> On Thu, Oct 28, 2021 at 10:28:01AM -0400, James Bottomley wrote:
>> If the block people are happy with this, then I'm OK with it, but it
>> doesn't look like you've solved the fanout deadlock problem because
>> this new mechanism is still going to allocate a new tag.
> 
> Yes, same problem as before.

Hi Christoph,

I spent some time looking around for other examples of allocating and
inserting a request from inside block layer callbacks. I only found one
such example, namely in the NVMe core. nvme_timeout() calls
nvme_alloc_request() and blk_execute_rq_nowait(). The difference between
what the UFS HPB code is doing and what nvme_timeout() does doesn't seem
that big to me. For clarity, I don't like the UFS HPB protocol nor how
support for that protocol has been implemented. However, I don't see how
the UFS HPB implementation would complicate maintenance of the block
layer core. Am I perhaps missing something?

Thanks,

Bart.

  reply	other threads:[~2021-10-28 17:07 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20211027223619epcms2p60bbc74c9ba9757c58709a99acd0892ff@epcms2p6>
2021-10-27 22:36 ` [PATCH] scsi: ufs: Fix proper API to send HPB pre-request Daejun Park
2021-10-28  4:16   ` Bart Van Assche
2021-10-28 14:28   ` James Bottomley
2021-10-28 15:27     ` Christoph Hellwig
2021-10-28 17:07       ` Bart Van Assche [this message]
2021-10-28 17:10         ` Christoph Hellwig
2021-10-28 15:59     ` Bart Van Assche
2021-10-28 19:12       ` James Bottomley
2021-10-28 20:04         ` Bart Van Assche
2021-10-28 20:12           ` James Bottomley
2021-10-28 21:20         ` Daejun Park
2021-10-28 15:22   ` James Bottomley
2021-10-29  1:32   ` Ming Lei
2021-10-29  1:50     ` Daejun Park
2021-10-29  2:10       ` Ming Lei
2021-10-29  2:50         ` Daejun Park
2021-10-29  3:14           ` Ming Lei
2021-10-29  4:39             ` Daejun Park

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