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Date:   Thu, 30 Mar 2023 07:58:23 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Dexuan Cui <decui@microsoft.com>
Cc:     Boqun Feng <boqun.feng@gmail.com>,
        "quic_jhugo@quicinc.com" <quic_jhugo@quicinc.com>,
        "quic_carlv@quicinc.com" <quic_carlv@quicinc.com>,
        "wei.liu@kernel.org" <wei.liu@kernel.org>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "sthemmin@microsoft.com" <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>,
        "helgaas@kernel.org" <helgaas@kernel.org>,
        "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH v2] PCI: hv: Fix the definition of vector in
 hv_compose_msi_msg()
Message-ID: <ZCUk_9YQGSfedCOR@kroah.com>
References: <20221027205256.17678-1-decui@microsoft.com>
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On Thu, Mar 30, 2023 at 03:23:45AM +0000, Dexuan Cui wrote:
> > From: Boqun Feng <boqun.feng@gmail.com>
> > Sent: Wednesday, March 29, 2023 7:56 PM
> > To: Dexuan Cui <decui@microsoft.com>
> >  ...
> > On Wed, Mar 29, 2023 at 06:56:12PM -0700, Boqun Feng wrote:
> > > [Cc stable]
> > >
> > > On Thu, Oct 27, 2022 at 01:52:56PM -0700, Dexuan Cui wrote:
> > > > The local variable 'vector' must be u32 rather than u8: see the
> > > > struct hv_msi_desc3.
> > > >
> > > > 'vector_count' should be u16 rather than u8: see struct hv_msi_desc,
> > > > hv_msi_desc2 and hv_msi_desc3.
> > > >
> > >
> > > Dexuan, I think this patch should only be in 5.15, because...
> > >
> > 
> > Sorry, I meant:
> > 
> > "this patch should also be backported in 5.15"
> > 
> > Regards,
> > Boqun
> > 
> > > > Fixes: a2bad844a67b ("PCI: hv: Fix interrupt mapping for multi-MSI")
> > >
> > > ^^^ this commit is already in 5.15.y (commit id 92dcb50f7f09).
> > >
> > > Upstream id e70af8d040d2b7904dca93d942ba23fb722e21b1
> > > Cc: <stable@vger.kernel.org> # 5.15.x
> 
> The faulty commit a2bad844a67b ("PCI: hv: Fix interrupt mapping for multi-MSI")
> is in all the stable branches, even including 4.14.y, so yes, the commit
> e70af8d040d2 ("PCI: hv: Fix the definition of vector in hv_compose_msi_msg()")
> should be backported to all the stable branches as well, including
> v5.15.y, v5.10.y, v5.4.y, v4.19.y, v4.14.y.
> 
> e70af8d040d2 has a Fixes tag. Not sure why it's not automatically backported.

Because "Fixes:" is not the flag that we are sure to trigger off of.
Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

That being said, because some subsystem maintainers do NOT put cc:
stable in their patches, we do sometimes sweep the tree and try to pick
up things with only "Fixes:" but we don't always catch everything.

So if you want to be sure a patch is applied, please always add a cc:
stable in the patch.

thanks,

greg k-h