unbind_from_irqhandler can end up doing /proc operations, which can't
happen under a spinlock. So before removing the IRQ handler,
disable the irq under the port_user lock (masking the underlying event
channel and making sure the irq handler isn't running concurrently and
won't start running), then remove the handler without the lock.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
evtchn_unbind_from_user() is called under a lock, so there's no need to
worry about the ordering of unbind_from_irqhandler vs clearing the port
per-user data.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
We only need the array when running as a Xen domain, so dynamically
allocate it as needed to save on bss space.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
enable/disable_irq() complain if the enables/disables are unbalanced,
so keep track of the state and avoid redundant enables.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Define a new per_user_data mutex to serialize bind/unbind operations
to prevent them from racing with each other. Fix error returns
and don't do a bind while holding a spinlock.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
This driver is used by application which wish to receive notifications
from the hypervisor or other guests via Xen's event channel
mechanism. In particular it is used by the xenstore daemon in domain
0.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
