From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030534Ab3HIHzm (ORCPT ); Fri, 9 Aug 2013 03:55:42 -0400 Received: from mail-bk0-f53.google.com ([209.85.214.53]:65169 "EHLO mail-bk0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967769Ab3HIHzj (ORCPT ); Fri, 9 Aug 2013 03:55:39 -0400 From: Tomasz Figa To: Cho KyongHo Cc: Tomasz Figa , "'Linux ARM Kernel'" , "'Linux IOMMU'" , "'Linux Kernel'" , "'Linux Samsung SOC'" , devicetree@vger.kernel.org, "'Joerg Roedel'" , "'Kukjin Kim'" , "'Prathyush'" , "'Rahul Sharma'" , "'Subash Patel'" , "'Grant Grundler'" , "'Antonios Motakis'" , kvmarm@lists.cs.columbia.edu, "'Sachin Kamat'" Subject: Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab Date: Fri, 09 Aug 2013 09:55:30 +0200 Message-ID: <2101296.S6JDU5igl3@flatron> User-Agent: KMail/4.10.5 (Linux/3.10.4-gentoo; KDE/4.10.5; x86_64; ; ) In-Reply-To: <20130809145849.790a9800f4f9893b30e54a1c@samsung.com> References: <002801ce941a$fb6369e0$f22a3da0$@samsung.com> <2544843.sndV7usHTj@amdc1227> <20130809145849.790a9800f4f9893b30e54a1c@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi KyongHo, On Friday 09 of August 2013 14:58:49 Cho KyongHo wrote: > 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 > > > --- > > > > > > 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. Oh, this is a valid point, but it was more a nitpick about the coding style. Single path error handling (with goto) is widely used in the kernel in cases when more than one thing has to be undone and so I suggested this method of error handling here as well. > Ok. I will process it separately. Since this patch adds most of the error handling to this function, I think it should be fine to do it as a part of this patch. Best regards, Tomasz