[Qemu-devel] [PATCH 06/12] Threadlet: Add dequeue_work threadlet API and remove active field.

[Arun R Bharadwaj <arun@linux.vnet.ibm.com>]

This patch adds dequeue_work threadlet API and shows how
the paio_cancel changes to dequeue_work.

The active field in the qemu_aiocb structure is now useless.
Remove it.

Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
---
 posix-aio-compat.c |   38 ++++++++++++++++----------------------
 1 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/posix-aio-compat.c b/posix-aio-compat.c
index 2ab1109..2d73846 100644
--- a/posix-aio-compat.c
+++ b/posix-aio-compat.c
@@ -69,7 +69,6 @@ struct qemu_paiocb {
 
     int aio_type;
     ssize_t ret;
-    int active;
     struct qemu_paiocb *next;
 
     int async_context_id;
@@ -346,7 +345,6 @@ static void handle_work(ThreadletWork *work)
     pid = getpid();
     qemu_mutex_lock(&aiocb_mutex);
     aiocb = container_of(work, struct qemu_paiocb, work);
-    aiocb->active = 1;
     qemu_mutex_unlock(&aiocb_mutex);
 
     switch (aiocb->aio_type & QEMU_AIO_TYPE_MASK) {
@@ -452,7 +450,6 @@ static void qemu_paio_submit(struct qemu_paiocb *aiocb)
 {
     qemu_mutex_lock(&aiocb_mutex);
     aiocb->ret = -EINPROGRESS;
-    aiocb->active = 0;
     qemu_mutex_unlock(&aiocb_mutex);
 
     aiocb->work.func = handle_work;
@@ -574,33 +571,30 @@ static void paio_remove(struct qemu_paiocb *acb)
     }
 }
 
-static void paio_cancel(BlockDriverAIOCB *blockacb)
+/**
+ * dequeue_work: Cancel a task queued on the global queue.
+ * @work: Contains the information of the task that needs to be cancelled.
+ */
+static int dequeue_work(ThreadletWork *work)
 {
-    struct qemu_paiocb *acb = (struct qemu_paiocb *)blockacb;
-    int active = 0;
-
-    qemu_mutex_lock(&aiocb_mutex);
     qemu_mutex_lock(&globalqueue.lock);
-    if (!acb->active) {
-        QTAILQ_REMOVE(&globalqueue.request_list, &acb->work, node);
-        acb->ret = -ECANCELED;
-    } else if (acb->ret == -EINPROGRESS) {
-        active = 1;
-    }
+    QTAILQ_REMOVE(&globalqueue.request_list, work, node);
     qemu_mutex_unlock(&globalqueue.lock);
 
-    if (!active) {
-        acb->ret = -ECANCELED;
-    } else {
+    return 0;
+}
+
+static void paio_cancel(BlockDriverAIOCB *blockacb)
+{
+    struct qemu_paiocb *acb = (struct qemu_paiocb *)blockacb;
+    if (dequeue_work(&acb->work) != 0) {
+        /* Wait for running work item to complete */
+        qemu_mutex_lock(&aiocb_mutex);
         while (acb->ret == -EINPROGRESS) {
-            /*
-             * fail safe: if the aio could not be canceled,
-             * we wait for it
-             */
             qemu_cond_wait(&aiocb_completion, &aiocb_mutex);
         }
+        qemu_mutex_unlock(&aiocb_mutex);
     }
-    qemu_mutex_unlock(&aiocb_mutex);
     paio_remove(acb);
 }