[Qemu-devel] [PATCH] ide: Fix ide_dma_cancel

[Qemu-devel] [PATCH] ide: Fix ide_dma_cancel

[Kevin Wolf]

When cancelling a request, bdrv_aio_cancel may decide that it waits for
completion of a request rather than for cancellation. IDE therefore can't
abandon its DMA status before calling bdrv_aio_cancel; otherwise the callback
of a completed request would use invalid data.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/ide/core.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 0757528..3cd55e3 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -2838,10 +2838,6 @@ static void ide_dma_restart(IDEState *s, int is_read)
 void ide_dma_cancel(BMDMAState *bm)
 {
     if (bm->status & BM_STATUS_DMAING) {
-        bm->status &= ~BM_STATUS_DMAING;
-        /* cancel DMA request */
-        bm->unit = -1;
-        bm->dma_cb = NULL;
         if (bm->aiocb) {
 #ifdef DEBUG_AIO
             printf("aio_cancel\n");
@@ -2849,6 +2845,10 @@ void ide_dma_cancel(BMDMAState *bm)
             bdrv_aio_cancel(bm->aiocb);
             bm->aiocb = NULL;
         }
+        bm->status &= ~BM_STATUS_DMAING;
+        /* cancel DMA request */
+        bm->unit = -1;
+        bm->dma_cb = NULL;
     }
 }
 
-- 
1.6.6.1

Re: [Qemu-devel] [PATCH] ide: Fix ide_dma_cancel

[Christoph Hellwig]

On Wed, May 05, 2010 at 11:54:56AM +0200, Kevin Wolf wrote:
> When cancelling a request, bdrv_aio_cancel may decide that it waits for
> completion of a request rather than for cancellation. IDE therefore can't
> abandon its DMA status before calling bdrv_aio_cancel; otherwise the callback
> of a completed request would use invalid data.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>

As mentioned before, looks good.


Reviewed-by: Christoph Hellwig <hch@lst.de>