[Qemu-devel] [STABLE][PATCH 3/3] Implement cancellation method for dma async I/O

[Ryan Harper <ryanh@us.ibm.com>]

Rebased on qemu-stable.

Move the dma helpers to a private aio pool, and implement a cancellation
method for them.  Should prevent issues when cancelling I/O while dma is
in progress.

Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/dma-helpers.c b/dma-helpers.c
index b2ade19..19fa4f0 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -10,6 +10,8 @@
 #include "dma.h"
 #include "block_int.h"
 
+static AIOPool dma_aio_pool;
+
 void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint)
 {
     qsg->sg = qemu_malloc(alloc_hint * sizeof(ScatterGatherEntry));
@@ -126,7 +128,7 @@ static BlockDriverAIOCB *dma_bdrv_io(
     DMABlockState *dbs = qemu_malloc(sizeof(*dbs));
 
     dbs->bs = bs;
-    dbs->acb = qemu_aio_get(bs, cb, opaque);
+    dbs->acb = qemu_aio_get_pool(&dma_aio_pool, bs, cb, opaque);
     dbs->sg = sg;
     dbs->sector_num = sector_num;
     dbs->sg_cur_index = 0;
@@ -153,3 +155,14 @@ BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
     return dma_bdrv_io(bs, sg, sector, cb, opaque, 1);
 }
 
+static void dma_aio_cancel(BlockDriverAIOCB *acb)
+{
+    DMABlockState *dbs = (DMABlockState *)acb->opaque;
+
+    bdrv_aio_cancel(dbs->acb);
+}
+
+void dma_helper_init(void)
+{
+    aio_pool_init(&dma_aio_pool, sizeof(BlockDriverAIOCB), dma_aio_cancel);
+}
diff --git a/dma.h b/dma.h
index d596717..7d2ab45 100644
--- a/dma.h
+++ b/dma.h
@@ -37,5 +37,6 @@ BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
 BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
                                  QEMUSGList *sg, uint64_t sector,
                                  BlockDriverCompletionFunc *cb, void *opaque);
+void dma_helper_init(void);
 
 #endif
diff --git a/vl.c b/vl.c
index 54ae45b..d6d8307 100644
--- a/vl.c
+++ b/vl.c
@@ -5485,6 +5485,7 @@ int main(int argc, char **argv, char **envp)
     cpu_exec_init_all(tb_size * 1024 * 1024);
 
     bdrv_init();
+    dma_helper_init();
 
     /* we always create the cdrom drive, even if no disk is there */