contrib/qemu: Import qemu block source code

This qemu block format source code and its minimal
dependency files will be used in the next patch to implement
a qemu-block format translator.

Change-Id: Ic87638972f7ea9b3df84d7a0539512a250c11c1c
BUG: 986775
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/5366
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

1 files changed, 135 insertions, 0 deletions

diff --git a/contrib/qemu/qemu-coroutine.c b/contrib/qemu/qemu-coroutine.c
new file mode 100644
index 000000000..423430d3a
--- /dev/null
+++ b/contrib/qemu/qemu-coroutine.c
@@ -0,0 +1,135 @@
+/*
+ * QEMU coroutines
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
+ *  Kevin Wolf         <kwolf@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "trace.h"
+#include "qemu-common.h"
+#include "qemu/thread.h"
+#include "block/coroutine.h"
+#include "block/coroutine_int.h"
+
+enum {
+    /* Maximum free pool size prevents holding too many freed coroutines */
+    POOL_MAX_SIZE = 64,
+};
+
+/** Free list to speed up creation */
+static QemuMutex pool_lock;
+static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
+static unsigned int pool_size;
+
+Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
+{
+    Coroutine *co;
+
+    qemu_mutex_lock(&pool_lock);
+    co = QSLIST_FIRST(&pool);
+    if (co) {
+        QSLIST_REMOVE_HEAD(&pool, pool_next);
+        pool_size--;
+    }
+    qemu_mutex_unlock(&pool_lock);
+
+    if (!co) {
+        co = qemu_coroutine_new();
+    }
+
+    co->entry = entry;
+    QTAILQ_INIT(&co->co_queue_wakeup);
+    return co;
+}
+
+static void coroutine_delete(Coroutine *co)
+{
+    qemu_mutex_lock(&pool_lock);
+    if (pool_size < POOL_MAX_SIZE) {
+        QSLIST_INSERT_HEAD(&pool, co, pool_next);
+        co->caller = NULL;
+        pool_size++;
+        qemu_mutex_unlock(&pool_lock);
+        return;
+    }
+    qemu_mutex_unlock(&pool_lock);
+
+    qemu_coroutine_delete(co);
+}
+
+static void __attribute__((constructor)) coroutine_pool_init(void)
+{
+    qemu_mutex_init(&pool_lock);
+}
+
+static void __attribute__((destructor)) coroutine_pool_cleanup(void)
+{
+    Coroutine *co;
+    Coroutine *tmp;
+
+    QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) {
+        QSLIST_REMOVE_HEAD(&pool, pool_next);
+        qemu_coroutine_delete(co);
+    }
+
+    qemu_mutex_destroy(&pool_lock);
+}
+
+static void coroutine_swap(Coroutine *from, Coroutine *to)
+{
+    CoroutineAction ret;
+
+    ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD);
+
+    qemu_co_queue_run_restart(to);
+
+    switch (ret) {
+    case COROUTINE_YIELD:
+        return;
+    case COROUTINE_TERMINATE:
+        trace_qemu_coroutine_terminate(to);
+        coroutine_delete(to);
+        return;
+    default:
+        abort();
+    }
+}
+
+void qemu_coroutine_enter(Coroutine *co, void *opaque)
+{
+    Coroutine *self = qemu_coroutine_self();
+
+    trace_qemu_coroutine_enter(self, co, opaque);
+
+    if (co->caller) {
+        fprintf(stderr, "Co-routine re-entered recursively\n");
+        abort();
+    }
+
+    co->caller = self;
+    co->entry_arg = opaque;
+    coroutine_swap(self, co);
+}
+
+void coroutine_fn qemu_coroutine_yield(void)
+{
+    Coroutine *self = qemu_coroutine_self();
+    Coroutine *to = self->caller;
+
+    trace_qemu_coroutine_yield(self, to);
+
+    if (!to) {
+        fprintf(stderr, "Co-routine is yielding to no one\n");
+        abort();
+    }
+
+    self->caller = NULL;
+    coroutine_swap(self, to);
+}