[Qemu-devel] [PATCH] dma-helpers: dma_blk_io() cancel support

[Stefan Hajnoczi <stefanha@redhat.com>]

Attempting to cancel a dma_blk_io() request causes an abort(3):

  void bdrv_aio_cancel(BlockAIOCB *acb)
  {
      ...
      while (acb->refcnt > 1) {
          if (acb->aiocb_info->get_aio_context) {
              aio_poll(acb->aiocb_info->get_aio_context(acb), true);
          } else if (acb->bs) {
              aio_poll(bdrv_get_aio_context(acb->bs), true);
          } else {
              abort();
          }
      }
      ...
  }

This happens because DMAAIOCB->bs is NULL and
dma_aiocb_info.get_aio_context() is also NULL.

This patch trivially implements dma_aiocb_info.get_aio_context() by
fetching the DMAAIOCB->ctx field.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 dma-helpers.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/dma-helpers.c b/dma-helpers.c
index b521d84..9defc10 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -185,10 +185,17 @@ static void dma_aio_cancel(BlockAIOCB *acb)
     }
 }
 
+static AioContext *dma_get_aio_context(BlockAIOCB *acb)
+{
+    DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
+
+    return dbs->ctx;
+}
 
 static const AIOCBInfo dma_aiocb_info = {
     .aiocb_size         = sizeof(DMAAIOCB),
     .cancel_async       = dma_aio_cancel,
+    .get_aio_context    = dma_get_aio_context,
 };
 
 BlockAIOCB *dma_blk_io(AioContext *ctx,
-- 
2.5.5