Re: [PATCH v4 02/15] util: vfio-helpers: Remove Error parameter from qemu_vfio_undo_mapping()

[Murilo Opsfelder Araújo]

On Thursday, March 5, 2020 11:29:32 AM -03 David Hildenbrand wrote:
> Everybody discards the error. Let's error_report() instead so this error
> doesn't get lost.
>
> This is now the same error handling as in qemu_vfio_do_mapping(). However,
> we don't report any errors via the return value to the caller. This seems
> to be one of these "will never happen, but let's better print an error
> because the caller can't handle it either way" cases.
>
> Cc: Richard Henderson <address@hidden>
> Cc: Paolo Bonzini <address@hidden>
> Cc: Eduardo Habkost <address@hidden>
> Cc: Marcel Apfelbaum <address@hidden>
> Cc: Alex Williamson <address@hidden>
> Cc: Stefan Hajnoczi <address@hidden>
> Signed-off-by: David Hildenbrand <address@hidden>
> ---

Acked-by: Murilo Opsfelder Araujo <address@hidden>

>  util/vfio-helpers.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
> index f31aa77ffe..7085ca702c 100644
> --- a/util/vfio-helpers.c
> +++ b/util/vfio-helpers.c
> @@ -541,8 +541,7 @@ static int qemu_vfio_do_mapping(QEMUVFIOState *s, void
> *host, size_t size, /**
>   * Undo the DMA mapping from @s with VFIO, and remove from mapping list.
>   */
> -static void qemu_vfio_undo_mapping(QEMUVFIOState *s, IOVAMapping *mapping,
> -                                   Error **errp)
> +static void qemu_vfio_undo_mapping(QEMUVFIOState *s, IOVAMapping *mapping)
>  {
>      int index;
>      struct vfio_iommu_type1_dma_unmap unmap = {
> @@ -557,7 +556,7 @@ static void qemu_vfio_undo_mapping(QEMUVFIOState *s,
> IOVAMapping *mapping, assert(QEMU_IS_ALIGNED(mapping->size,
> qemu_real_host_page_size)); assert(index >= 0 && index < s->nr_mappings);
>      if (ioctl(s->container, VFIO_IOMMU_UNMAP_DMA, &unmap)) {
> -        error_setg_errno(errp, errno, "VFIO_UNMAP_DMA failed");
> +        error_report("VFIO_UNMAP_DMA failed: %s", strerror(errno));
>      }
>      memmove(mapping, &s->mappings[index + 1],
>              sizeof(s->mappings[0]) * (s->nr_mappings - index - 1));
> @@ -622,7 +621,7 @@ int qemu_vfio_dma_map(QEMUVFIOState *s, void *host,
> size_t size, assert(qemu_vfio_verify_mappings(s));
>              ret = qemu_vfio_do_mapping(s, host, size, iova0);
>              if (ret) {
> -                qemu_vfio_undo_mapping(s, mapping, NULL);
> +                qemu_vfio_undo_mapping(s, mapping);
>                  goto out;
>              }
>              s->low_water_mark += size;
> @@ -682,7 +681,7 @@ void qemu_vfio_dma_unmap(QEMUVFIOState *s, void *host)
>      if (!m) {
>          goto out;
>      }
> -    qemu_vfio_undo_mapping(s, m, NULL);
> +    qemu_vfio_undo_mapping(s, m);
>  out:
>      qemu_mutex_unlock(&s->lock);
>  }
> @@ -699,7 +698,7 @@ void qemu_vfio_close(QEMUVFIOState *s)
>          return;
>      }
>      while (s->nr_mappings) {
> -        qemu_vfio_undo_mapping(s, &s->mappings[s->nr_mappings - 1], NULL);
> +        qemu_vfio_undo_mapping(s, &s->mappings[s->nr_mappings - 1]);
>      }
>      ram_block_notifier_remove(&s->ram_notifier);
>      qemu_vfio_reset(s);


--
Murilo