linux-kernel - RE: [PATCH 1/1] PCI: hv: Remove unused field pci_bus in struct hv_pcibus

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Message-ID:
 <SN6PR02MB4157BFB422607900AC1EBD82D481A@SN6PR02MB4157.namprd02.prod.outlook.com>
Date: Mon, 12 Jan 2026 15:54:51 +0000
From: Michael Kelley <mhklinux@...look.com>
To: "Srivatsa S. Bhat" <srivatsa@...il.mit.edu>
CC: "kys@...rosoft.com" <kys@...rosoft.com>, "haiyangz@...rosoft.com"
	<haiyangz@...rosoft.com>, "wei.liu@...nel.org" <wei.liu@...nel.org>,
	"decui@...rosoft.com" <decui@...rosoft.com>, "longli@...rosoft.com"
	<longli@...rosoft.com>, "lpieralisi@...nel.org" <lpieralisi@...nel.org>,
	"kwilczynski@...nel.org" <kwilczynski@...nel.org>, "mani@...nel.org"
	<mani@...nel.org>, "robh@...nel.org" <robh@...nel.org>, "bhelgaas@...gle.com"
	<bhelgaas@...gle.com>, "linux-pci@...r.kernel.org"
	<linux-pci@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-hyperv@...r.kernel.org"
	<linux-hyperv@...r.kernel.org>
Subject: RE: [PATCH 1/1] PCI: hv: Remove unused field pci_bus in struct
 hv_pcibus_device

From: Srivatsa S. Bhat <srivatsa@...il.mit.edu> Sent: Monday, January 12, 2026 6:29 AM
> Hi Michael,
> 
> On Sun, Jan 11, 2026 at 09:00:34AM -0800, mhkelley58@...il.com wrote:
> > From: Michael Kelley <mhklinux@...look.com>
> >
> > Field pci_bus in struct hv_pcibus_device is unused since
> > commit 418cb6c8e051 ("PCI: hv: Generify PCI probing"). Remove it.
> >
> 
> Since that commit is several years old (2021), I was curious if this was found by
> manual inspection or if the compiler was able to flag the unused
> variable as well.

Code inspection. I was brushing up on how the structs defined
in pci-hyperv.c relate to the standard Linux PCI struct pci_bus and
struct pci_dev. Having a pointer to struct pci_bus in struct
hv_pcibus_device makes sense, and I was a bit surprised to find
it's not set or used. Instead, the PCI bus is always found through
the PCI bridge.

Michael

> 
> > No functional change.
> >
> > Signed-off-by: Michael Kelley <mhklinux@...look.com>
> 
> Reviewed-by: Srivatsa S. Bhat (Microsoft) <srivatsa@...il.mit.edu>
> 
> Regards,
> Srivatsa
> Microsoft Linux Systems Group
> 
> > ---
> >  drivers/pci/controller/pci-hyperv.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> > index 1e237d3538f9..7fcba05cec30 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -501,7 +501,6 @@ struct hv_pcibus_device {
> >  	struct resource *low_mmio_res;
> >  	struct resource *high_mmio_res;
> >  	struct completion *survey_event;
> > -	struct pci_bus *pci_bus;
> >  	spinlock_t config_lock;	/* Avoid two threads writing index page */
> >  	spinlock_t device_list_lock;	/* Protect lists below */
> >  	void __iomem *cfg_addr;
> > --
> > 2.25.1
> >
> >