[Qemu-devel] [PATCH 4/4] linux-aio: simplify removal of completed iocbs from the list

[Paolo Bonzini]

There is no need to do another O(n) pass on the list; the iocb to
splice the list at is already available in the array we passed to
io_submit.

Signed-off-by: Paolo Bonzini <address@hidden>
---
 block/linux-aio.c    | 12 ++++++------
 include/qemu/queue.h | 11 +++++++++++
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/block/linux-aio.c b/block/linux-aio.c
index b223d9e..6c98f72 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -186,9 +186,10 @@ static void ioq_init(LaioQueue *io_q)
 
 static int ioq_submit(struct qemu_laio_state *s)
 {
-    int ret, i, len;
+    int ret, len;
     struct qemu_laiocb *aiocb;
     struct iocb *iocbs[MAX_QUEUED_IO];
+    QSIMPLEQ_HEAD(, qemu_laiocb) completed;
 
     do {
         len = 0;
@@ -201,16 +202,15 @@ static int ioq_submit(struct qemu_laio_state *s)
 
         ret = io_submit(s->ctx, len, iocbs);
         if (ret == -EAGAIN) {
-            ret = 0;
+            break;
         }
         if (ret < 0) {
             abort();
         }
 
-        for (i = 0; i < ret; i++) {
-            s->io_q.n--;
-            QSIMPLEQ_REMOVE_HEAD(&s->io_q.pending, next);
-        }
+        s->io_q.n -= ret;
+        aiocb = container_of(iocbs[ret - 1], struct qemu_laiocb, iocb);
+        QSIMPLEQ_SPLIT_AFTER(&completed, &s->io_q.pending, aiocb, next);
     } while (ret == len && !QSIMPLEQ_EMPTY(&s->io_q.pending));
     s->io_q.blocked = (s->io_q.n > 0);
 
diff --git a/include/qemu/queue.h b/include/qemu/queue.h
index 0dedd29..2c21d28 100644
--- a/include/qemu/queue.h
+++ b/include/qemu/queue.h
@@ -279,6 +279,17 @@ struct {                                                   
             \
         (head)->sqh_last = &(head)->sqh_first;                          \
 } while (/*CONSTCOND*/0)
 
+#define QSIMPLEQ_SPLIT_AFTER(head1, head2, elm, field) do {             \
+    if (((head1)->sqh_first = (head2)->sqh_first) == NULL) {            \
+        (head1)->sqh_last = &(head1)->sqh_first;                        \
+    } else {                                                            \
+        (head1)->sqh_last = &(elm)->field.sqe_next;                     \
+        if (((head2)->sqh_first = (elm)->field.sqe_next) == NULL) {     \
+            (head2)->sqh_last = &(head2)->sqh_first;                    \
+        }                                                               \
+    }                                                                   \
+} while (/*CONSTCOND*/0)
+
 #define QSIMPLEQ_REMOVE(head, elm, type, field) do {                    \
     if ((head)->sqh_first == (elm)) {                                   \
         QSIMPLEQ_REMOVE_HEAD((head), field);                            \
-- 
2.1.0