From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F015218C32B; Sun, 28 Jul 2024 16:09:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722182978; cv=none; b=K/N7VN4jYaG6DN6vCsva7BrR0Lzqcz+66lAsgGZDu9Z+c13b9WYuQjlpMmODTVFcRFrcci442+HonJWMtTP+CgCMqdwfSHPkyMM3DTcuY5Fqtp/XqPkp0OMUK5oxtzipUXTRy+pttALfRJJhiah284xDEb9tf8NVJcD7/pi22nI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722182978; c=relaxed/simple; bh=IRrehuAqkOzgt1Xl6qCITtkVEYrUQrqrwJfEH2s9ayE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=T8vQpXfZe/4WbyrkiTgQAIS+CEmTHC+NHrAhHkH+zOpNHX3jddD9oJrGeCnFeXAwubI4fDC7VSDKy24OugthD3ZB5D66K8mR9AHf2T0R/Q54acjqXCVQ07fZfYBXXM0utn7y6wlkYo50TS9i9C7/7f7l8x5ZJt1rW9SwckG9iRc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dJCxQ59g; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dJCxQ59g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77F37C32782; Sun, 28 Jul 2024 16:09:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722182977; bh=IRrehuAqkOzgt1Xl6qCITtkVEYrUQrqrwJfEH2s9ayE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dJCxQ59g8fyq4/oyHbcUsH1jBmaVTs4VOld4jXMlWeuFJvQ0KqOGKm9MpA+4B2oVs Sr7iYrRxAE9N8wR3D7FUcJcWhaKqWUEqm/KmeoAvkPbA06XDIxM4VbL6Fz6dokBxCR Y2J+JwLl7nhNRIDMDI/In8LxCjSqBiAqc9X5Tcdx198nTD1AHSBHAURdsaOHGc75gd 1l8OvH1iVkrazZiJ96bS3k1yZ8E9Lqu/lrxTlgZz4P5XS+49m4Zsh6hOq3z+hZa/Pg Axyny8oy49NH2NoufXvPF1QF/bSSRVxOmJ/+/GSQqDkBSxNyFRPGp/DXMuqLl6Hk0b RD6DGvq0q+7OA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jiwei Sun , Adrian Huang , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , Bjorn Helgaas , Nirmal Patel , Sasha Levin , lpieralisi@kernel.org, kw@linux.com, linux-pci@vger.kernel.org Subject: [PATCH AUTOSEL 5.15 11/13] PCI: vmd: Create domain symlink before pci_bus_add_devices() Date: Sun, 28 Jul 2024 12:08:53 -0400 Message-ID: <20240728160907.2053634-11-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240728160907.2053634-1-sashal@kernel.org> References: <20240728160907.2053634-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.164 Content-Transfer-Encoding: 8bit From: Jiwei Sun [ Upstream commit f24c9bfcd423e2b2bb0d198456412f614ec2030a ] The vmd driver creates a "domain" symlink in sysfs for each VMD bridge. Previously this symlink was created after pci_bus_add_devices() added devices below the VMD bridge and emitted udev events to announce them to userspace. This led to a race between userspace consumers of the udev events and the kernel creation of the symlink. One such consumer is mdadm, which assembles block devices into a RAID array, and for devices below a VMD bridge, mdadm depends on the "domain" symlink. If mdadm loses the race, it may be unable to assemble a RAID array, which may cause a boot failure or other issues, with complaints like this: (udev-worker)[2149]: nvme1n1: '/sbin/mdadm -I /dev/nvme1n1'(err) 'mdadm: Unable to get real path for '/sys/bus/pci/drivers/vmd/0000:c7:00.5/domain/device'' (udev-worker)[2149]: nvme1n1: '/sbin/mdadm -I /dev/nvme1n1'(err) 'mdadm: /dev/nvme1n1 is not attached to Intel(R) RAID controller.' (udev-worker)[2149]: nvme1n1: '/sbin/mdadm -I /dev/nvme1n1'(err) 'mdadm: No OROM/EFI properties for /dev/nvme1n1' (udev-worker)[2149]: nvme1n1: '/sbin/mdadm -I /dev/nvme1n1'(err) 'mdadm: no RAID superblock on /dev/nvme1n1.' (udev-worker)[2149]: nvme1n1: Process '/sbin/mdadm -I /dev/nvme1n1' failed with exit code 1. This symptom prevents the OS from booting successfully. After a NVMe disk is probed/added by the nvme driver, udevd invokes mdadm to detect if there is a mdraid associated with this NVMe disk, and mdadm determines if a NVMe device is connected to a particular VMD domain by checking the "domain" symlink. For example: Thread A Thread B Thread mdadm vmd_enable_domain pci_bus_add_devices __driver_probe_device ... work_on_cpu schedule_work_on : wakeup Thread B nvme_probe : wakeup scan_work to scan nvme disk and add nvme disk then wakeup udevd : udevd executes mdadm command flush_work main : wait for nvme_probe done ... __driver_probe_device find_driver_devices : probe next nvme device : 1) Detect domain symlink ... 2) Find domain symlink ... from vmd sysfs ... 3) Domain symlink not ... created yet; failed sysfs_create_link : create domain symlink Create the VMD "domain" symlink before invoking pci_bus_add_devices() to avoid this race. Suggested-by: Adrian Huang Link: https://lore.kernel.org/linux-pci/20240605124844.24293-1-sjiwei@163.com Signed-off-by: Jiwei Sun Signed-off-by: Krzysztof Wilczyński [bhelgaas: commit log] Signed-off-by: Bjorn Helgaas Reviewed-by: Nirmal Patel Signed-off-by: Sasha Levin --- drivers/pci/controller/vmd.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c index f49001ba96c75..10a078ef4799d 100644 --- a/drivers/pci/controller/vmd.c +++ b/drivers/pci/controller/vmd.c @@ -798,6 +798,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features) if (vmd->irq_domain) dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain); + WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj, + "domain"), "Can't create symlink to domain\n"); + vmd_acpi_begin(); pci_scan_child_bus(vmd->bus); @@ -814,9 +817,6 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features) pci_bus_add_devices(vmd->bus); vmd_acpi_end(); - - WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj, - "domain"), "Can't create symlink to domain\n"); return 0; } @@ -873,8 +873,8 @@ static void vmd_remove(struct pci_dev *dev) { struct vmd_dev *vmd = pci_get_drvdata(dev); - sysfs_remove_link(&vmd->dev->dev.kobj, "domain"); pci_stop_root_bus(vmd->bus); + sysfs_remove_link(&vmd->dev->dev.kobj, "domain"); pci_remove_root_bus(vmd->bus); vmd_cleanup_srcu(vmd); vmd_detach_resources(vmd); -- 2.43.0