On Sat, 09/03 01:56, Michael S. Tsirkin wrote:

On Wed, Jun 29, 2016 at 09:24:15AM +0800, Fam Zheng wrote:

quoted

On Tue, 06/28 04:45, Christoph Hellwig wrote:

quoted

On Tue, Jun 28, 2016 at 10:39:15AM +0800, Fam Zheng wrote:

quoted

Userspace listens to the KOBJ_ADD uevent generated in add_disk. At that
point we haven't created the serial attribute file, therefore depending
on how fast udev reacts, the /dev/disk/by-id/ entry doesn't always get
created.

This race condition can be easily reproduced by hot plugging a number of
virtio-blk disks.

Also in systemd, there used to be a related workaround in udev rules
called 'WAIT_FOR="serial"', but it is removed in later versions.

Now let's generate a KOBJ_CHANGE event after the attributes are ready.

The same race is present in other drivers as well, e.g. nvme.  Please
find a way to make this work properly without needing to hack every
driver to send events manually.

OK, I'll take a look today!

Fam

Was this fixed in the generic code?

A proposed fix is:

https://lkml.org/lkml/2016/8/17/81

Fam