seqlock: add QemuLockable support

A shortcut when the seqlock write is protected by a spinlock or any mutex
other than the BQL.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/qemu/seqlock.h b/include/qemu/seqlock.h
index c367516708..fd408b7ec5 100644
--- a/include/qemu/seqlock.h
+++ b/include/qemu/seqlock.h
@@ -16,6 +16,7 @@
 
 #include "qemu/atomic.h"
 #include "qemu/thread.h"
+#include "qemu/lockable.h"
 
 typedef struct QemuSeqLock QemuSeqLock;
 
@@ -45,6 +46,25 @@ static inline void seqlock_write_end(QemuSeqLock *sl)
     atomic_set(&sl->sequence, sl->sequence + 1);
 }
 
+/* Lock out other writers and update the count.  */
+static inline void seqlock_write_lock_impl(QemuSeqLock *sl, QemuLockable *lock)
+{
+    qemu_lockable_lock(lock);
+    seqlock_write_begin(sl);
+}
+#define seqlock_write_lock(sl, lock) \
+    seqlock_write_lock_impl(sl, QEMU_MAKE_LOCKABLE(lock))
+
+/* Lock out other writers and update the count.  */
+static inline void seqlock_write_unlock_impl(QemuSeqLock *sl, QemuLockable *lock)
+{
+    qemu_lockable_unlock(lock);
+    seqlock_write_begin(sl);
+}
+#define seqlock_write_unlock(sl, lock) \
+    seqlock_write_unlock_impl(sl, QEMU_MAKE_LOCKABLE(lock))
+
+
 static inline unsigned seqlock_read_begin(const QemuSeqLock *sl)
 {
     /* Always fail if a write is in progress.  */