Re: [PATCH] Revert "iommu/arm-smmu: Convert to domain_alloc_paging()"

From: Jason Gunthorpe <jgg@ziepe.ca>
To: Will Deacon <will@kernel.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>, Rob Clark <robdclark@gmail.com>,
	linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
	linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH] Revert "iommu/arm-smmu: Convert to domain_alloc_paging()"
Date: Tue, 13 Feb 2024 09:47:26 -0400	[thread overview]
Message-ID: <20240213134726.GK765010@ziepe.ca> (raw)
In-Reply-To: <20240213125951.GB28844@willie-the-truck>

On Tue, Feb 13, 2024 at 12:59:52PM +0000, Will Deacon wrote:
> > The typical kernel standard is to fix bugs in patches and only reach
> > for a wholesale revert if the community is struggling with bug
> > fixing. Dmitry already tested removing that hunk, Robin explained the
> > issue, we understand the bug fix is to remove the
> > arm_smmu_init_domain_context() call. Nothing justifies a full scale
> > revert.
> 
> I can't say I'm aware of any consensus for how to handle this, to be
> completely honest with you. 

Well, I work in a lot of subsystems and this is a surprise to me and
not something I've seen before. Fix the bug, move forward. Reverts are
a cultural admission of failure. I use threats of a revert as a hammer
to encourage people to pay attention to the bugs. I hardly ever
actually revert things. What does reverting their code say to my
submitters???

> > I'll send another patch if you want, but it seems like a waste of all
> > our time.
> 
> It's a bug fix, of course it's a waste of time! We're talking minutes
> though, right?

It becomes hard for maintainers to juggle the tress since you have to
send the revert to -rc and the fix on top of the rc to next. Again, I
will send the patch, just discussing.

Jason