linux-kernel - [PATCH 0/2] PCI/IOV: Add missing PCI rescan-remove locking when enabling/disabling SR-IOV

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Message-Id: <20250826-pci_fix_sriov_disable-v1-0-2d0bc938f2a3@linux.ibm.com>
Date: Tue, 26 Aug 2025 10:52:07 +0200
From: Niklas Schnelle <schnelle@...ux.ibm.com>
To: Bjorn Helgaas <helgaas@...nel.org>, Lukas Wunner <lukas@...ner.de>
Cc: Keith Busch <kbusch@...nel.org>, Gerd Bayer <gbayer@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Benjamin Block <bblock@...ux.ibm.com>,
        Halil Pasic <pasic@...ux.ibm.com>, Farhan Ali <alifm@...ux.ibm.com>,
        Julian Ruess <julianr@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, Niklas Schnelle <schnelle@...ux.ibm.com>
Subject: [PATCH 0/2] PCI/IOV: Add missing PCI rescan-remove locking when
 enabling/disabling SR-IOV

Hi Bjorn, Hi Lukas,

This series fixes missing PCI rescan-remove locking in sriov_disable()
and sriov_enable() the former of which was observed to cause a double
remove / list corruption on s390. The first patch is the fix itself and
gives more details while the second patch is an optional proposal to add
a lockdep assertion to pci_stop_and_remove_bus_device() to catch missing
rescan-remove locking more easily in the future. If applied without the
first patch disabling SR-IOV via "echo 0 > /sys/bus/pci/devices/<dev>
/sriov_numvfs" triggers the lockdep assertion. I haven't found an easy
way to trigger the assertion in the sriov_enable() case but I checked
callers.

Also since the sriov_add_vfs() path is not excercised on s390 due to
pdev->no_vf_scan I did some basic testing on an x86 test system with an
SR-IOV capable ConnectX-6 DX NIC.

Thanks,
Niklas

Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
---
Niklas Schnelle (2):
      PCI/IOV: Add missing PCI rescan-remove locking when enabling/disabling SR-IOV
      PCI: Add lockdep assertion in pci_stop_and_remove_bus_device()

 drivers/pci/iov.c    | 5 +++++
 drivers/pci/pci.h    | 2 ++
 drivers/pci/probe.c  | 2 +-
 drivers/pci/remove.c | 1 +
 4 files changed, 9 insertions(+), 1 deletion(-)
---
base-commit: 1b237f190eb3d36f52dffe07a40b5eb210280e00
change-id: 20250821-pci_fix_sriov_disable-552f29c822dd

Best regards,
-- 
Niklas Schnelle