These serve no purpose, but to add to the congnitive load of following
the code. Remove the level of indirection.
Furthermore, the lock protects all data in vm_event_domain, making
ring_lock a poor choice of name.
For vm_event_get_response() and vm_event_grab_slot(), fold the exit
paths to have a single unlock, as the compiler can't make this
optimisation itself.
No functional change.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Razvan Cojocaru <rcojoc...@bitdefender.com>
CC: Tamas K Lengyel <ta...@tklengyel.com>
CC: Petre Pircalabu <ppircal...@bitdefender.com>
---
xen/common/vm_event.c | 58 ++++++++++++++++++++++++-------------------------
xen/include/xen/sched.h | 3 +--
2 files changed, 30 insertions(+), 31 deletions(-)
diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index 902e152..db975e9 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -35,10 +35,6 @@
#define xen_rmb() smp_rmb()
#define xen_wmb() smp_wmb()
-#define vm_event_ring_lock_init(_ved) spin_lock_init(&(_ved)->ring_lock)
-#define vm_event_ring_lock(_ved) spin_lock(&(_ved)->ring_lock)
-#define vm_event_ring_unlock(_ved) spin_unlock(&(_ved)->ring_lock)
-
static int vm_event_enable(
struct domain *d,
struct xen_domctl_vm_event_op *vec,
@@ -66,8 +62,8 @@ static int vm_event_enable(
if ( ring_gfn == 0 )
return -EOPNOTSUPP;
- vm_event_ring_lock_init(*ved);
- vm_event_ring_lock(*ved);
+ spin_lock_init(&(*ved)->lock);
+ spin_lock(&(*ved)->lock);
rc = vm_event_init_domain(d);
@@ -101,13 +97,13 @@ static int vm_event_enable(
/* Initialize the last-chance wait queue. */
init_waitqueue_head(&(*ved)->wq);
- vm_event_ring_unlock(*ved);
+ spin_unlock(&(*ved)->lock);
return 0;
err:
destroy_ring_for_helper(&(*ved)->ring_page,
(*ved)->ring_pg_struct);
- vm_event_ring_unlock(*ved);
+ spin_unlock(&(*ved)->lock);
xfree(*ved);
*ved = NULL;
@@ -200,11 +196,11 @@ static int vm_event_disable(struct domain *d, struct
vm_event_domain **ved)
{
struct vcpu *v;
- vm_event_ring_lock(*ved);
+ spin_lock(&(*ved)->lock);
if ( !list_empty(&(*ved)->wq.list) )
{
- vm_event_ring_unlock(*ved);
+ spin_unlock(&(*ved)->lock);
return -EBUSY;
}
@@ -226,7 +222,7 @@ static int vm_event_disable(struct domain *d, struct
vm_event_domain **ved)
vm_event_cleanup_domain(d);
- vm_event_ring_unlock(*ved);
+ spin_unlock(&(*ved)->lock);
}
xfree(*ved);
@@ -292,7 +288,7 @@ void vm_event_put_request(struct domain *d,
req->version = VM_EVENT_INTERFACE_VERSION;
- vm_event_ring_lock(ved);
+ spin_lock(&ved->lock);
/* Due to the reservations, this step must succeed. */
front_ring = &ved->front_ring;
@@ -319,7 +315,7 @@ void vm_event_put_request(struct domain *d,
!atomic_read(&curr->vm_event_pause_count) )
vm_event_mark_and_pause(curr, ved);
- vm_event_ring_unlock(ved);
+ spin_unlock(&ved->lock);
notify_via_xen_event_channel(d, ved->xen_port);
}
@@ -329,17 +325,15 @@ static int vm_event_get_response(struct domain *d, struct
vm_event_domain *ved,
{
vm_event_front_ring_t *front_ring;
RING_IDX rsp_cons;
+ int rc = 0;
- vm_event_ring_lock(ved);
+ spin_lock(&ved->lock);
front_ring = &ved->front_ring;
rsp_cons = front_ring->rsp_cons;
if ( !RING_HAS_UNCONSUMED_RESPONSES(front_ring) )
- {
- vm_event_ring_unlock(ved);
- return 0;
- }
+ goto out;
/* Copy response */
memcpy(rsp, RING_GET_RESPONSE(front_ring, rsp_cons), sizeof(*rsp));
@@ -353,9 +347,12 @@ static int vm_event_get_response(struct domain *d, struct
vm_event_domain *ved,
* there may be additional space available in the ring. */
vm_event_wake(d, ved);
- vm_event_ring_unlock(ved);
+ rc = 1;
- return 1;
+ out:
+ spin_unlock(&ved->lock);
+
+ return rc;
}
/*
@@ -455,35 +452,38 @@ void vm_event_cancel_slot(struct domain *d, struct
vm_event_domain *ved)
if( !vm_event_check_ring(ved) )
return;
- vm_event_ring_lock(ved);
+ spin_lock(&ved->lock);
vm_event_release_slot(d, ved);
- vm_event_ring_unlock(ved);
+ spin_unlock(&ved->lock);
}
static int vm_event_grab_slot(struct vm_event_domain *ved, int foreign)
{
unsigned int avail_req;
+ int rc;
if ( !ved->ring_page )
return -EOPNOTSUPP;
- vm_event_ring_lock(ved);
+ spin_lock(&ved->lock);
avail_req = vm_event_ring_available(ved);
+
+ rc = -EBUSY;
if ( avail_req == 0 )
- {
- vm_event_ring_unlock(ved);
- return -EBUSY;
- }
+ goto out;
if ( !foreign )
ved->target_producers++;
else
ved->foreign_producers++;
- vm_event_ring_unlock(ved);
+ rc = 0;
- return 0;
+ out:
+ spin_unlock(&ved->lock);
+
+ return rc;
}
/* Simple try_grab wrapper for use in the wait_event() macro. */
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 2201fac..b9691fc 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -282,8 +282,7 @@ struct vcpu
/* VM event */
struct vm_event_domain
{
- /* ring lock */
- spinlock_t ring_lock;
+ spinlock_t lock;
/* The ring has 64 entries */
unsigned char foreign_producers;
unsigned char target_producers;
--
2.1.4
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
