tree 0c8b69dbc2de5aea96be93a24a8b39dbb9256b88
parent 0cc678f850f2cba0cedbd133fcbbf175554cd6c6
author Daniel De Graaf <dgdegra@tycho.nsa.gov> 1319752727 -0400
committer Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> 1321913688 -0500

xen/event: Add reference counting to event channels

Event channels exposed to userspace by the evtchn module may be used by
other modules in an asynchronous manner, which requires that reference
counting be used to prevent the event channel from being closed before
the signals are delivered.

The reference count on new event channels defaults to -1 which indicates
the event channel is not referenced outside the kernel; evtchn_get fails
if called on such an event channel. The event channels made visible to
userspace by evtchn have a normal reference count.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>