From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965381Ab3HIIwK (ORCPT ); Fri, 9 Aug 2013 04:52:10 -0400 Received: from mailout2.samsung.com ([203.254.224.25]:30339 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932235Ab3HIIwF (ORCPT ); Fri, 9 Aug 2013 04:52:05 -0400 X-AuditID: cbfee68e-b7f276d000002279-c3-5204adac3f0d Date: Fri, 09 Aug 2013 17:51:56 +0900 From: Cho KyongHo To: Tomasz Figa 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 Message-id: <20130809175156.c7ffc68b865e4bca48ef47dd@samsung.com> In-reply-to: <2101296.S6JDU5igl3@flatron> References: <002801ce941a$fb6369e0$f22a3da0$@samsung.com> <2544843.sndV7usHTj@amdc1227> <20130809145849.790a9800f4f9893b30e54a1c@samsung.com> <2101296.S6JDU5igl3@flatron> X-Mailer: Sylpheed 3.3.0 (GTK+ 2.10.14; i686-pc-mingw32) MIME-version: 1.0 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpileLIzCtJLcpLzFFi42I5/e+Zoe7atSxBBr+PM1ncuXuO1WL+ESDx 6sgPJosF+60tOmdvYLfoXXCVzeLjqePsFpseX2O1uLxrDpvFjPP7mCwurNjIbjFl0WFWi5N/ ehktWq73Mlmsn/GaxWLVrj+MDgIeTw7OY/KY3XCRxWPnrLvsHneu7WHzOL9pDbPH5iX1HpNv LGf06NuyitHj8yY5jytHzzAFcEVx2aSk5mSWpRbp2yVwZdydUF4wV7NiXd9/9gbGVXJdjBwc EgImEl/+pHQxcgKZYhIX7q1nA7GFBJYxShxeoAIRN5F49ekLYxcjF1B8EaPEhT+7mCCcSUwS +/4cAOtgEVCV2PPoPSuIzSagJbF67nFGEFtEQF3i25R+dpAGZoE5rBJPli5jAUkICwRLbHr2 E6yIV8BRYv2VTUwgNqeApsS8xjaoDRsYJRYs+sgKcYeFxIWmDnaIBkGJH5PvgQ1iBtq2eVsT K4QtL7F5zVtmkGYJgS0cEtdOnGaCOE9A4tvkQywQP8tKbDrADDFTUuLgihssExjFZiEZOwvJ 2FlIxi5gZF7FKJpakFxQnJReZKRXnJhbXJqXrpecn7uJERL/fTsYbx6wPsSYDLRyIrOUaHI+ MH3klcQbGpsZWZiamBobmVuakSasJM6r1mIdKCSQnliSmp2aWpBaFF9UmpNafIiRiYNTqoFx wyOXJSvvT1yjE3nPu1KDt1rq7DlZk3Vrq84Iz+2/uUGG+3NQy0OWg4rfthkcuSdS7LjF1+nb XHa7tEyV60ZiX07bNnPWdXM95JDfsN9dQP9hUL/4lZL7D7KaNMxDc46+9bhSzvUjI16rbI3j nWMymhb5zRIC00QNNRofPRPfbm6oncfX26DEUpyRaKjFXFScCACVmjhKFQMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrIKsWRmVeSWpSXmKPExsVy+t9jAd01a1mCDL4dsbS4c/ccq8X8I0Di 1ZEfTBYL9ltbdM7ewG7Ru+Aqm8XHU8fZLTY9vsZqcXnXHDaLGef3MVlcWLGR3WLKosOsFif/ 9DJatFzvZbJYP+M1i8WqXX8YHQQ8nhycx+Qxu+Eii8fOWXfZPe5c28PmcX7TGmaPzUvqPSbf WM7o0bdlFaPH501yHleOnmEK4IpqYLTJSE1MSS1SSM1Lzk/JzEu3VfIOjneONzUzMNQ1tLQw V1LIS8xNtVVy8QnQdcvMAfpFSaEsMacUKBSQWFyspG+HaUJoiJuuBUxjhK5vSBBcj5EBGkhY x5hxd0J5wVzNinV9/9kbGFfJdTFyckgImEi8+vSFEcIWk7hwbz1bFyMXh5DAIkaJC392MUE4 k5gk9v05wAZSxSKgKrHn0XtWEJtNQEti9dzjYN0iAuoS36b0s4M0MAvMYZV4snQZC0hCWCBY YtOzn2BFvAKOEuuvbGICsTkFNCXmNbZBbdjAKLFg0UdWiDssJC40dbBDNAhK/Jh8D2wQM9C2 zduaWCFseYnNa94yT2AUmIWkbBaSsllIyhYwMq9iFE0tSC4oTkrPNdIrTswtLs1L10vOz93E CE4wz6R3MK5qsDjEKMDBqMTDq7idOUiINbGsuDL3EKMEB7OSCO/2CSxBQrwpiZVVqUX58UWl OanFhxiTgeExkVlKNDkfmPzySuINjU3MjCyNzCyMTMzNSRNWEuc92GodKCSQnliSmp2aWpBa BLOFiYNTqoExIMsxLOOj+pktq89UOX1IO8T+8seyBTN+cty261R5tWDJ7mX8/qtUsiscpFaJ v17WIfmnYcnSMKOfNlddvMp/sS5ruH/j4RwHT+3MH//m8x2IEsio2N+yrWDOtSbBaqkLKsz6 mpMW8zLPsm+rn2HEfzw9LLd1zzWT0Bv3tqVnblk1c8rPKJEaJZbijERDLeai4kQA7aujGHQD AAA= DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 09 Aug 2013 09:55:30 +0200, Tomasz Figa wrote: > 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. > I meant 'separately' that checking all return values each. I think it can be simpler without goto. There are just 2 cases to rollback previous changes in that function. > Best regards, > Tomasz >