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

Cho KyongHo
2013-08-09T05:58:54Z

On Thu, 08 Aug 2013 16:00:18 +0200, Tomasz Figa wrote:
> 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;
> }
>

Thank you for suggestion.
I think you are worrying about missing the information who makes 'ret' non-zero.
Ok. I will process it separately.

thanks

KyongHo.
> Best regards,
> Tomasz
>