[Qemu-devel] [PATCH 08/10] fifolock: create rfifolock_is_owner helper

["Denis V. Lunev" <den@openvz.org>]

This helper is necessary to ensure locking constraints.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
---
 include/qemu/rfifolock.h |  1 +
 util/rfifolock.c         | 12 +++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/qemu/rfifolock.h b/include/qemu/rfifolock.h
index b23ab53..1148cb0 100644
--- a/include/qemu/rfifolock.h
+++ b/include/qemu/rfifolock.h
@@ -50,5 +50,6 @@ void rfifolock_init(RFifoLock *r, void (*cb)(void *), void *opaque);
 void rfifolock_destroy(RFifoLock *r);
 void rfifolock_lock(RFifoLock *r);
 void rfifolock_unlock(RFifoLock *r);
+bool rfifolock_is_owner(RFifoLock *r);
 
 #endif /* QEMU_RFIFOLOCK_H */
diff --git a/util/rfifolock.c b/util/rfifolock.c
index afbf748..4533617 100644
--- a/util/rfifolock.c
+++ b/util/rfifolock.c
@@ -12,6 +12,7 @@
  */
 
 #include <assert.h>
+#include <string.h>
 #include "qemu/rfifolock.h"
 
 void rfifolock_init(RFifoLock *r, void (*cb)(void *), void *opaque)
@@ -48,7 +49,7 @@ void rfifolock_lock(RFifoLock *r)
     /* Take a ticket */
     unsigned int ticket = r->tail++;
 
-    if (r->nesting > 0 && qemu_thread_is_self(&r->owner_thread)) {
+    if (rfifolock_is_owner(r)) {
         r->tail--; /* put ticket back, we're nesting */
     } else {
         while (ticket != r->head) {
@@ -68,11 +69,16 @@ void rfifolock_lock(RFifoLock *r)
 void rfifolock_unlock(RFifoLock *r)
 {
     qemu_mutex_lock(&r->lock);
-    assert(r->nesting > 0);
-    assert(qemu_thread_is_self(&r->owner_thread));
+    assert(rfifolock_is_owner(r));
     if (--r->nesting == 0) {
+        memset(&r->owner_thread, 0, sizeof(r->owner_thread));
         r->head++;
         qemu_cond_broadcast(&r->cond);
     }
     qemu_mutex_unlock(&r->lock);
 }
+
+bool rfifolock_is_owner(RFifoLock *r)
+{
+    return r->nesting > 0 && qemu_thread_is_self(&r->owner_thread);
+}
-- 
2.5.0