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From:   Dexuan Cui <decui@microsoft.com>
To:     Bjorn Helgaas <helgaas@kernel.org>
CC:     "quic_jhugo@quicinc.com" <quic_jhugo@quicinc.com>,
        "wei.liu@kernel.org" <wei.liu@kernel.org>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        "lpieralisi@kernel.org" <lpieralisi@kernel.org>,
        "bhelgaas@google.com" <bhelgaas@google.com>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Michael Kelley (LINUX)" <mikelley@microsoft.com>,
        "robh@kernel.org" <robh@kernel.org>, "kw@linux.com" <kw@linux.com>,
        "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
        "boqun.feng@gmail.com" <boqun.feng@gmail.com>,
        Boqun Feng <Boqun.Feng@microsoft.com>,
        Carl Vanderlip <quic_carlv@quicinc.com>
Subject: RE: [PATCH] PCI: hv: Only reuse existing IRTE allocation for
 Multi-MSI
Thread-Topic: [PATCH] PCI: hv: Only reuse existing IRTE allocation for
 Multi-MSI
Thread-Index: AQHYsYgIr0ByY5vvCEupYVpg2kRVKK2yAnlw
Date:   Tue, 16 Aug 2022 21:13:26 +0000
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References: <20220804025104.15673-1-decui@microsoft.com>
 <20220816155122.GA2064495@bhelgaas>
In-Reply-To: <20220816155122.GA2064495@bhelgaas>
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> From: Bjorn Helgaas <helgaas@kernel.org>
> Sent: Tuesday, August 16, 2022 8:51 AM
> To: Dexuan Cui <decui@microsoft.com>
>=20
> This has only observations with no explanations, and I don't see how
> it will be useful to future readers of the git history.
Please see the below.
=20
> I assume you bisected the problem to b4b77778ecc5? =20
Yes.

> Can you just revert that?  A revert requires no more explanation than
>  "this broke something."

It's better to not revert b4b77778ecc5, which is required by Jeff's
Multi-MSI device, which doesn't seem to be affected by the interrupt
issue I described.

> I guess this is a fine distinction, but I really don't like random
> code changes that "seem to avoid a problem but we don't know how."
> A revert at least has the advantage that we can cover our eyes and
> pretend the commit never happened. This patch feels like future
> readers will have to try to understand the code even though we
> clearly don't understand why it makes a difference.

I just replied to Lorenzo's email with more details. FYI, this is the link
to my reply:
https://lwn.net/ml/linux-kernel/SA1PR21MB1335D08F987BBAE08EADF010BF6B9@SA1P=
R21MB1335.namprd21.prod.outlook.com/
=20
I just felt the commit message might be too long if I had put all the
details there. :-) Can we add a Links: tag?

Thanks,
-- Dexuan