By keeping a count of the number of currently valid event channels,
port_is_valid() can be simplified.
d->valid_evtchns is only increased (while holding d->event_lock), so
port_is_valid() may be safely called without taking the lock (this
will be useful later).
Signed-off-by: David Vrabel <david.vra...@citrix.com>
---
v3:
- Remove redundant d->evtchn test.
v2:
- Used unsigned int for d->valid_evtchns.
---
xen/common/event_channel.c | 3 +++
xen/include/xen/event.h | 6 +-----
xen/include/xen/sched.h | 5 +++--
3 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index ab3b48e..4924796 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -189,6 +189,8 @@ static int get_free_port(struct domain *d)
return -ENOMEM;
bucket_from_port(d, port) = chn;
+ write_atomic(&d->valid_evtchns, d->valid_evtchns + EVTCHNS_PER_BUCKET);
+
return port;
}
@@ -1232,6 +1234,7 @@ int evtchn_init(struct domain *d)
d->evtchn = alloc_evtchn_bucket(d, 0);
if ( !d->evtchn )
return -ENOMEM;
+ d->valid_evtchns = EVTCHNS_PER_BUCKET;
spin_lock_init_prof(d, event_lock);
if ( get_free_port(d) != 0 )
diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
index 690f865..af923d1 100644
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -89,11 +89,7 @@ static inline bool_t port_is_valid(struct domain *d,
unsigned int p)
{
if ( p >= d->max_evtchns )
return 0;
- if ( !d->evtchn )
- return 0;
- if ( p < EVTCHNS_PER_BUCKET )
- return 1;
- return group_from_port(d, p) != NULL && bucket_from_port(d, p) != NULL;
+ return p < read_atomic(&d->valid_evtchns);
}
static inline struct evtchn *evtchn_from_port(struct domain *d, unsigned int p)
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 80c6f62..604d047 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -336,8 +336,9 @@ struct domain
/* Event channel information. */
struct evtchn *evtchn; /* first bucket only */
struct evtchn **evtchn_group[NR_EVTCHN_GROUPS]; /* all other buckets */
- unsigned int max_evtchns;
- unsigned int max_evtchn_port;
+ unsigned int max_evtchns; /* number supported by ABI */
+ unsigned int max_evtchn_port; /* max permitted port number */
+ unsigned int valid_evtchns; /* number of allocated event channels */
spinlock_t event_lock;
const struct evtchn_port_ops *evtchn_port_ops;
struct evtchn_fifo_domain *evtchn_fifo;
--
1.7.10.4
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