Re: [PATCH 8/8] dma: Let dma_buf_read() / dma_buf_write() propagate MemTxResult

[Philippe Mathieu-Daudé]

On 12/16/21 13:35, Philippe Mathieu-Daudé wrote:
> Since the previous commit, dma_buf_rw() returns a MemTxResult
> type. Do not discard it, return it to the caller.
> 
> Since both dma_buf_read/dma_buf_write functions were previously
> returning the QEMUSGList size not consumed, add an extra argument
> where the unconsummed size can be stored.
> 
> Update the few callers.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  include/sysemu/dma.h  |  6 ++++--
>  hw/ide/ahci.c         |  8 ++++----
>  hw/nvme/ctrl.c        |  4 ++--
>  hw/scsi/megasas.c     | 48 ++++++++++++++++++++++++++++++-------------
>  hw/scsi/scsi-bus.c    |  4 ++--
>  softmmu/dma-helpers.c | 18 ++++++----------
>  6 files changed, 52 insertions(+), 36 deletions(-)
> 
> diff --git a/include/sysemu/dma.h b/include/sysemu/dma.h
> index cdf379fecad..9f998edbea4 100644
> --- a/include/sysemu/dma.h
> +++ b/include/sysemu/dma.h
> @@ -303,8 +303,10 @@ BlockAIOCB *dma_blk_read(BlockBackend *blk,
>  BlockAIOCB *dma_blk_write(BlockBackend *blk,
>                            QEMUSGList *sg, uint64_t offset, uint32_t align,
>                            BlockCompletionFunc *cb, void *opaque);
> -uint64_t dma_buf_read(void *ptr, int32_t len, QEMUSGList *sg, MemTxAttrs 
> attrs);
> -uint64_t dma_buf_write(void *ptr, int32_t len, QEMUSGList *sg, MemTxAttrs 
> attrs);
> +MemTxResult dma_buf_read(void *ptr, int32_t len, uint64_t *residp,
> +                         QEMUSGList *sg, MemTxAttrs attrs);
> +MemTxResult dma_buf_write(void *ptr, int32_t len, uint64_t *residp,
> +                          QEMUSGList *sg, MemTxAttrs attrs);

Side note, ideally all functions returning the MemTxResult
type should use the warn_unused_result attribute.