[Qemu-devel] [RFC PATCH 7/9] dma: Implement .cancel_async

[Fam Zheng <famz@redhat.com>]

Just forward the request to bdrv_aio_cancel_async. Use a flag to fix the
ret value in completion code. Also check memory address before calling
dma_memory_unmap.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 dma-helpers.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/dma-helpers.c b/dma-helpers.c
index 499b52b..4a03e18 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -74,6 +74,7 @@ typedef struct {
     uint64_t sector_num;
     DMADirection dir;
     bool in_cancel;
+    bool cancelled;
     int sg_cur_index;
     dma_addr_t sg_cur_byte;
     QEMUIOVector iov;
@@ -105,6 +106,9 @@ static void dma_bdrv_unmap(DMAAIOCB *dbs)
     int i;
 
     for (i = 0; i < dbs->iov.niov; ++i) {
+        if (!(dbs->iov.iov[i].iov_base && dbs->iov.iov[i].iov_len)) {
+            break;
+        }
         dma_memory_unmap(dbs->sg->as, dbs->iov.iov[i].iov_base,
                          dbs->iov.iov[i].iov_len, dbs->dir,
                          dbs->iov.iov[i].iov_len);
@@ -116,6 +120,9 @@ static void dma_complete(DMAAIOCB *dbs, int ret)
 {
     trace_dma_complete(dbs, ret, dbs->common.cb);
 
+    if (dbs->cancelled) {
+        ret = -ECANCELED;
+    }
     dma_bdrv_unmap(dbs);
     if (dbs->common.cb) {
         dbs->common.cb(dbs->common.opaque, ret);
@@ -141,6 +148,9 @@ static void dma_bdrv_cb(void *opaque, int ret)
 
     trace_dma_bdrv_cb(dbs, ret);
 
+    if (dbs->cancelled) {
+        ret = -ECANCELED;
+    }
     dbs->acb = NULL;
     dbs->sector_num += dbs->iov.size / 512;
 
@@ -185,6 +195,7 @@ static void dma_aio_cancel(BlockDriverAIOCB *acb)
 
     trace_dma_aio_cancel(dbs);
 
+    dbs->cancelled = true;
     if (dbs->acb) {
         BlockDriverAIOCB *acb = dbs->acb;
         dbs->acb = NULL;
@@ -196,9 +207,25 @@ static void dma_aio_cancel(BlockDriverAIOCB *acb)
     dma_complete(dbs, 0);
 }
 
+static void dma_aio_cancel_async(BlockDriverAIOCB *acb)
+{
+    DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
+
+    trace_dma_aio_cancel(dbs);
+
+    dbs->cancelled = true;
+    if (dbs->acb) {
+        acb = dbs->acb;
+        dbs->acb = NULL;
+        bdrv_aio_cancel_async(acb);
+    }
+}
+
+
 static const AIOCBInfo dma_aiocb_info = {
     .aiocb_size         = sizeof(DMAAIOCB),
     .cancel             = dma_aio_cancel,
+    .cancel_async       = dma_aio_cancel_async,
 };
 
 BlockDriverAIOCB *dma_bdrv_io(
@@ -218,6 +245,7 @@ BlockDriverAIOCB *dma_bdrv_io(
     dbs->sg_cur_byte = 0;
     dbs->dir = dir;
     dbs->in_cancel = false;
+    dbs->cancelled = false;
     dbs->io_func = io_func;
     dbs->bh = NULL;
     qemu_iovec_init(&dbs->iov, sg->nsg);
-- 
2.0.3