Race between "mount" uevent and /proc/mounts?

Schupp Roderich (extern) BenQ MD PD SWP 2 CM MCH
2005-10-25T13:20:15Z

Hi,

the 2.6.13 and 2.6.14-* kernels seem susceptible to a race condition
between the sending of a "mount" uevent and the actual mount becoming
visible thru /proc/mounts, at least when the kernel is configured
with voluntary preemption.

The following scenario:
- system is using the HAL daemon, configured to monitor kernel uvents
- someone (usually some kind of volume manager in response to
a device hotplug, but could also a manual mount) mounts a filesystem
- "mount" uevent is emitted
- HAL daemon reads the event, then opens and reads /proc/mounts
(in order to determine the corresponding mount point, since the uevent
contains only the sysfs device name), but /proc/mounts does not
(yet) contain the corresponding line

There has been one previous post about this:
http://marc.theaimsgroup.com/?l=linux-kernel&m=112670567427154

Cheers, Roderich