Re: [PATCH v2] PCI: hv: Fix the definition of vector in hv_compose_msi_msg() - Greg Kroah-Hartman

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()
Date: Thu, 30 Mar 2023 07:58:23 +0200	[thread overview]
Message-ID: <ZCUk_9YQGSfedCOR@kroah.com> (raw)
In-Reply-To: <SA1PR21MB13354973735A5E727F94A169BF8E9@SA1PR21MB1335.namprd21.prod.outlook.com>

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