From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D51C4C77D8 for ; Fri, 21 Aug 2026 14:25:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787322306; cv=none; b=XXnJ5jUL6As+761L4gYPp2JgoiZM6UlHvfHAXmDSX0wF1bdzijhRLDYx65yUGljSkvuAHHKkFrtm04dGIpPZ9clE5Ybo5w8vIrH+7VlIgx3LmKTJQqBts0MHSOCFEgTEZ6Y/gHkNLanpkv1qOaHCMXLxLt0ZwdEdyE+awA/7jQo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787322306; c=relaxed/simple; bh=3lQMPdYbR1RntwK+bxjJtg5kiwvAYZO4Z6X9Nwg+SoI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=G+Y54zxFDYqfvoNtZ3tsUX4RwvXn5Z86ChrHzGL/EU0HPMPwOcjLl8hfuAOM6zaH95sbVuEzDTCbDtERPfyszIRAlW+Db+hzvop+//b5VpsJHzLnuxa/Ryr4aTjePR+ZYFshr07WEYlS9/+5uYrrcW4tKXp+17QEfPaxLhWI1AE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=hzf/B062; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hzf/B062" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1787322299; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IU0vv4gN2o5y5prXUpJQRh2FejWBebUitlBF1Qr8ENg=; b=hzf/B062LxjQ1EylGuLR0L1jWOBLeIyksEzCzCqDr+AgSoWJx5yHrmA3Z5tzF8rYcW2tEh JXe26KsjWKxQveAD4njSatNkAfk/l1epB8jGEGJmA7srX2fus+s1Mn3IgTdNf+x15YINgV 10nZ4J9rWceIgdaNOwhzec4njYicrag= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-255-E0vuZrlmMeSZFl2-63xpJw-1; Fri, 21 Aug 2026 10:24:55 -0400 X-MC-Unique: E0vuZrlmMeSZFl2-63xpJw-1 X-Mimecast-MFC-AGG-ID: E0vuZrlmMeSZFl2-63xpJw_1787322293 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 22CFF1954208; Fri, 21 Aug 2026 14:24:53 +0000 (UTC) Received: from djeffery-thinkpadp1gen3.redhat.corp (headnet05.pony-001.prod.iad2.dc.redhat.com [10.2.32.117]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9C2E6180034F; Fri, 21 Aug 2026 14:24:50 +0000 (UTC) From: David Jeffery To: driver-core@lists.linux.dev, Greg Kroah-Hartman , "Rafael J. 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, David Jeffery Subject: [PATCH 3/9] driver core: warn should device_move try to move a need_parent_lock device Date: Fri, 21 Aug 2026 10:24:08 -0400 Message-ID: <20260821142414.150892-4-djeffery@redhat.com> In-Reply-To: <20260821142414.150892-1-djeffery@redhat.com> References: <20260821142414.150892-1-djeffery@redhat.com> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: MWKOepUfwro99tBC5_BV2O9MyIlkmqpFyWLroqbiIYg_1787322293 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. 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 bd9c2921e326..75f5931165a8 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -4712,6 +4712,14 @@ 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