Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

Tomasz Figa
2013-08-08T14:00:29Z

On Thursday 08 of August 2013 18:38:04 Cho KyongHo wrote:
> Since kmalloc() does not guarantee that the allignment of 1KiB when it
> allocates 1KiB, it is required to allocate lv2 page table from own
> slab that guarantees alignment of 1KiB
>
> Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
> ---
> drivers/iommu/exynos-iommu.c | 24 ++++++++++++++++++++----
> 1 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index d90e6fa..a318049 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -100,6 +100,8 @@
> #define REG_PB1_SADDR 0x054
> #define REG_PB1_EADDR 0x058
>
> +static struct kmem_cache *lv2table_kmem_cache;
> +
> static unsigned long *section_entry(unsigned long *pgtable, unsigned
> long iova) {
> return pgtable + lv1ent_offset(iova);
> @@ -765,7 +767,8 @@ static void exynos_iommu_domain_destroy(struct
> iommu_domain *domain)
>
> for (i = 0; i < NUM_LV1ENTRIES; i++)
> if (lv1ent_page(priv->pgtable + i))
> - kfree(__va(lv2table_base(priv->pgtable + i)));
> + kmem_cache_free(lv2table_kmem_cache,
> + __va(lv2table_base(priv->pgtable + i)));
>
> free_pages((unsigned long)priv->pgtable, 2);
> free_pages((unsigned long)priv->lv2entcnt, 1);
> @@ -861,7 +864,7 @@ static unsigned long *alloc_lv2entry(unsigned long
> *sent, unsigned long iova, if (lv1ent_fault(sent)) {
> unsigned long *pent;
>
> - pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
> + pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
> BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
> if (!pent)
> return ERR_PTR(-ENOMEM);
> @@ -881,7 +884,7 @@ static int lv1set_section(unsigned long *sent,
> phys_addr_t paddr, short *pgcnt)
>
> if (lv1ent_page(sent)) {
> BUG_ON(*pgcnt != NUM_LV2ENTRIES);
> - kfree(page_entry(sent, 0));
> + kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
> *pgcnt = 0;
> }
>
> @@ -1082,10 +1085,23 @@ static int __init exynos_iommu_init(void)
> {
> int ret;
>
> + lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> + LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> + if (!lv2table_kmem_cache) {
> + pr_err("%s: Failed to create kmem cache\n", __func__);
> + return -ENOMEM;
> + }
> +
> ret = platform_driver_register(&exynos_sysmmu_driver);
>
> if (ret == 0)
> - bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> + ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> +
> + if (ret) {
> + pr_err("%s: Failed to register exynos-iommu driver.\n",
> + __func__);
> + kmem_cache_destroy(lv2table_kmem_cache);
> + }

What about making the return value handling here cleaner? For example:

lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
if (!lv2table_kmem_cache) {
...
return -ENOMEM;
}

ret = platform_driver_register(&exynos_sysmmu_driver);
if (ret) {
...
goto err_destroy_kmem_cache;
}

ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
if (ret) {
...
goto err_platform_unregister;
}

return 0;

err_platform_unregister:
...
err_destroy_kmem_cache:
...
return ret;
}

Best regards,
Tomasz