Re: [PATCH v1 05/10] powerpc/pseries/iommu: Add iommu_pseries_alloc_table() helper

Alexey Kardashevskiy
2020-08-24T00:39:09Z

On 18/08/2020 09:40, Leonardo Bras wrote:
> Creates a helper to allow allocating a new iommu_table without the need
> to reallocate the iommu_group.
>
> This will be helpful for replacing the iommu_table for the new DMA window,
> after we remove the old one with iommu_tce_table_put().
>
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> ---
> arch/powerpc/platforms/pseries/iommu.c | 25 ++++++++++++++-----------
> 1 file changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 8fe23b7dff3a..39617ce0ec83 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -53,28 +53,31 @@ enum {
> DDW_EXT_QUERY_OUT_SIZE = 2
> };
>
> -static struct iommu_table_group *iommu_pseries_alloc_group(int node)
> +static struct iommu_table *iommu_pseries_alloc_table(int node)
> {
> - struct iommu_table_group *table_group;
> struct iommu_table *tbl;
>
> - table_group = kzalloc_node(sizeof(struct iommu_table_group), GFP_KERNEL,
> - node);
> - if (!table_group)
> - return NULL;
> -
> tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL, node);
> if (!tbl)
> - goto free_group;
> + return NULL;
>
> INIT_LIST_HEAD_RCU(&tbl->it_group_list);
> kref_init(&tbl->it_kref);
> + return tbl;
> +}
>
> - table_group->tables[0] = tbl;
> +static struct iommu_table_group *iommu_pseries_alloc_group(int node)
> +{
> + struct iommu_table_group *table_group;
> +
> + table_group = kzalloc_node(sizeof(*table_group), GFP_KERNEL, node);

I'd prefer you did not make unrelated changes (sizeof(struct
iommu_table_group) -> sizeof(*table_group)) so the diff stays shorter
and easier to follow. You changed sizeof(struct iommu_table_group) but
not sizeof(struct iommu_table) and this confused me enough to spend more
time than this straight forward change deserves.

Not important in this case though so

Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>

> + if (!table_group)
> + return NULL;
>
> - return table_group;
> + table_group->tables[0] = iommu_pseries_alloc_table(node);
> + if (table_group->tables[0])
> + return table_group;
>
> -free_group:
> kfree(table_group);
> return NULL;
> }
>

--
Alexey