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Wysocki" , Danilo Krummrich Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, Tarun Sahu , Stuart Hayes , Laurence Oberman , Bjorn Helgaas , kexec@lists.infradead.org, "Ewan Milne" , "John Meneghini" , "Lombardi, Maurizio" , "Bart Van Assche" , "John Garry" , "Jeremy Allison" , "Martin K . Petersen" , "Pasha Tatashin" , David Jeffery Subject: [PATCH 3/9] driver core: warn should device_move try to move a need_parent_lock device Date: Tue, 20 Oct 2026 12:44:29 -0400 Message-ID: <20261020164435.80499-4-djeffery@redhat.com> In-Reply-To: <20261020164435.80499-1-djeffery@redhat.com> References: <20261020164435.80499-1-djeffery@redhat.com> X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: gKtaDc3HaWqaCale1egq6nvpiP2rd2XyQx20qT0DYyM_1792514696 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Currently, no device has need_parent_lock set and is moved by device_move. need_parent_lock is only set by the usb bus and very few device types ever use device_move. Add a warning to device_move to catch should it ever be used on a device with need_parent_lock set. The combination would break the immutable relationship needed between parent and child for need_parent_lock when locking and unlocking both. Suggested-by: Tarun Sahu Signed-off-by: David Jeffery Tested-by: Laurence Oberman --- drivers/base/core.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/base/core.c b/drivers/base/core.c index bce555dd74f6..e8a62c8f0ad3 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -4705,6 +4705,14 @@ int device_move(struct device *dev, struct device *new_parent, if (!dev) return -EINVAL; + /* + * device_move() should not be used on devices with need_parent_lock + * set. Concurrent reparenting will violate the immutable + * relationship needed while locking and unlocking both parent and + * child. + */ + WARN_ON(dev->bus && dev->bus->need_parent_lock); + device_pm_lock(); new_parent = get_device(new_parent); new_parent_kobj = get_device_parent(dev, new_parent); -- 2.55.0