netdev - Re: [PATCH 8/8] dm-verity: Convert from tasklet to BH workqueue

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Date: Wed, 31 Jan 2024 19:19:16 -0500
From: Mike Snitzer <snitzer@...nel.org>
To: Tejun Heo <tj@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
	Mikulas Patocka <mpatocka@...hat.com>, linux-kernel@...r.kernel.org,
	dm-devel@...ts.linux.dev, msnitzer@...hat.com, ignat@...udflare.com,
	damien.lemoal@....com, bob.liu@...cle.com, houtao1@...wei.com,
	peterz@...radead.org, mingo@...nel.org, netdev@...r.kernel.org,
	allen.lkml@...il.com, kernel-team@...a.com,
	Alasdair Kergon <agk@...hat.com>
Subject: Re: [PATCH 8/8] dm-verity: Convert from tasklet to BH workqueue

On Wed, Jan 31 2024 at  7:04P -0500,
Tejun Heo <tj@...nel.org> wrote:

> Hello, Linus.
> 
> On Wed, Jan 31, 2024 at 03:19:01PM -0800, Linus Torvalds wrote:
> > On Wed, 31 Jan 2024 at 13:32, Tejun Heo <tj@...nel.org> wrote:
> > >
> > > I don't know, so just did the dumb thing. If the caller always guarantees
> > > that the work items are never queued at the same time, reusing is fine.
> > 
> > So the reason I thought it would be a good cleanup to introduce that
> > "atomic" workqueue thing (now "bh") was that this case literally has a
> > switch between "use tasklets' or "use workqueues".
> > 
> > So it's not even about "reusing" the workqueue, it's literally a
> > matter of making it always just use workqueues, and the switch then
> > becomes just *which* workqueue to use - system or bh.
> 
> Yeah, that's how the dm-crypt got converted. The patch just before this one.
> This one probably can be converted the same way. I don't see the work item
> being re-initialized. It probably is better to initialize the work item
> together with the enclosing struct and then just queue it when needed.

Sounds good.
 
> Mikulas, I couldn't decide what to do with the "try_verify_in_tasklet"
> option and just decided to do the minimal thing hoping that someone more
> familiar with the code can take over the actual conversion. How much of user
> interface commitment is that? Should it be renamed or would it be better to
> leave it be?

cryptsetup did add support for it, so I think it worthwhile to
preserve the option; but it'd be fine to have it just be a backward
compatible alias for a more appropriately named option?

Mike