From: Jiwei Sun <sunjw10@xxxxxxxxxx>
During booting into the kernel, the following error message appears:
(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, the udevd executes
some rule scripts by invoking mdadm command to detect if there is a
mdraid associated with this NVMe disk. The mdadm determines if one
NVMe devce is connected to a particular VMD domain by checking the
domain symlink. Here is the root cause:
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 the domain
... symlink; 2) Find the
... domain symlink from
... vmd sysfs; 3) The
... domain symlink is not
... created yet, failed
sysfs_create_link
: create domain symlink
sysfs_create_link() is invoked at the end of vmd_enable_domain().
However, this implementation introduces a timing issue, where mdadm
might fail to retrieve the vmd symlink path because the symlink has not
been created yet.
Fix the issue by creating VMD domain symlinks before invoking
pci_bus_add_devices().
Signed-off-by: Jiwei Sun <sunjw10@xxxxxxxxxx>
Suggested-by: Adrian Huang <ahuang12@xxxxxxxxxx>
---
v3 changes:
- Per Paul's comment, move sysfs_remove_link() after
pci_stop_root_bus()
v2 changes:
- Add "()" after function names in subject and commit log
- Move sysfs_create_link() after vmd_attach_resources()
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 87b7856f375a..4e7fe2e13cac 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -925,6 +925,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
dev_set_msi_domain(&vmd->bus->dev,
dev_get_msi_domain(&vmd->dev->dev));
+ 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);
@@ -964,9 +967,6 @@ 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;
}
@@ -1042,8 +1042,8 @@ 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);
--
2.27.0
