From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751516AbeBWOp2 (ORCPT ); Fri, 23 Feb 2018 09:45:28 -0500 Received: from mail-lf0-f65.google.com ([209.85.215.65]:41245 "EHLO mail-lf0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751317AbeBWOp1 (ORCPT ); Fri, 23 Feb 2018 09:45:27 -0500 X-Google-Smtp-Source: AG47ELuaaaEUo8PpS900VoAfmpJvBARNk2AcvKM+HqywR3aYfR2ZkMyTegXxH+0xBsxLLg/xWLPCCQ== Subject: Re: [PATCH 5/9] drm/xen-front: Implement handling of shared display buffers To: Boris Ostrovsky , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, airlied@linux.ie, daniel.vetter@intel.com, seanpaul@chromium.org, gustavo@padovan.org, jgross@suse.com, konrad.wilk@oracle.com Cc: Oleksandr Andrushchenko References: <1519200222-20623-1-git-send-email-andr2000@gmail.com> <1519200222-20623-6-git-send-email-andr2000@gmail.com> <11ce6c96-1739-435c-4b6f-c9f5d02a2905@oracle.com> <36003bb4-6fc9-f8f9-2817-103bf0f543e9@oracle.com> From: Oleksandr Andrushchenko Message-ID: Date: Fri, 23 Feb 2018 16:45:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <36003bb4-6fc9-f8f9-2817-103bf0f543e9@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/23/2018 04:36 PM, Boris Ostrovsky wrote: > On 02/23/2018 02:53 AM, Oleksandr Andrushchenko wrote: >> On 02/23/2018 02:25 AM, Boris Ostrovsky wrote: >>> On 02/21/2018 03:03 AM, Oleksandr Andrushchenko wrote: >>>> static int __init xen_drv_init(void) >>>> { >>>> + /* At the moment we only support case with XEN_PAGE_SIZE == >>>> PAGE_SIZE */ >>>> + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); >>> Why BUILD_BUG_ON? This should simply not load if page sizes are >>> different. >>> >>> >> This is a compile time check, so if kernel/Xen is configured >> to use page size combination which is not supported by the >> driver it will fail during compilation. This seems correct to me, >> because you shouldn't even try to load the driver which >> cannot handle different page sizes to not make any harm. > > This will prevent whole kernel from building. So, for example, > randconfig builds will fail. > makes a lot of sense, thank you will rework so I reject to load if the requirement is not met >>> >>> >>>> + ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages); >>>> + BUG_ON(ret); >>> We should try not to BUG*(). There are a few in this patch (and possibly >>> others) that I think can be avoided. >>> >> I will rework BUG_* for map/unmap code to handle errors, >> but will still leave >> /* either pages or sgt, not both */ >> BUG_ON(cfg->pages && cfg->sgt); >> which is a real driver bug and must not happen > Why not return an error? > > In fact, AFAICS you only call it in patch 9 where both of these can be > tested, in which case something like -EINVAL would look reasonable. ok, will remove BUG_ON as well > -boris From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleksandr Andrushchenko Subject: Re: [PATCH 5/9] drm/xen-front: Implement handling of shared display buffers Date: Fri, 23 Feb 2018 16:45:23 +0200 Message-ID: References: <1519200222-20623-1-git-send-email-andr2000@gmail.com> <1519200222-20623-6-git-send-email-andr2000@gmail.com> <11ce6c96-1739-435c-4b6f-c9f5d02a2905@oracle.com> <36003bb4-6fc9-f8f9-2817-103bf0f543e9@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: Received: from mail-lf0-x241.google.com (mail-lf0-x241.google.com [IPv6:2a00:1450:4010:c07::241]) by gabe.freedesktop.org (Postfix) with ESMTPS id DDA666F188 for ; Fri, 23 Feb 2018 14:45:27 +0000 (UTC) Received: by mail-lf0-x241.google.com with SMTP id 70so12699876lfw.2 for ; Fri, 23 Feb 2018 06:45:27 -0800 (PST) In-Reply-To: <36003bb4-6fc9-f8f9-2817-103bf0f543e9@oracle.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Boris Ostrovsky , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, airlied@linux.ie, daniel.vetter@intel.com, seanpaul@chromium.org, gustavo@padovan.org, jgross@suse.com, konrad.wilk@oracle.com Cc: Oleksandr Andrushchenko List-Id: dri-devel@lists.freedesktop.org T24gMDIvMjMvMjAxOCAwNDozNiBQTSwgQm9yaXMgT3N0cm92c2t5IHdyb3RlOgo+IE9uIDAyLzIz LzIwMTggMDI6NTMgQU0sIE9sZWtzYW5kciBBbmRydXNoY2hlbmtvIHdyb3RlOgo+PiBPbiAwMi8y My8yMDE4IDAyOjI1IEFNLCBCb3JpcyBPc3Ryb3Zza3kgd3JvdGU6Cj4+PiBPbiAwMi8yMS8yMDE4 IDAzOjAzIEFNLCBPbGVrc2FuZHIgQW5kcnVzaGNoZW5rbyB3cm90ZToKPj4+PiAgICAgIHN0YXRp YyBpbnQgX19pbml0IHhlbl9kcnZfaW5pdCh2b2lkKQo+Pj4+ICAgIHsKPj4+PiArICAgIC8qIEF0 IHRoZSBtb21lbnQgd2Ugb25seSBzdXBwb3J0IGNhc2Ugd2l0aCBYRU5fUEFHRV9TSVpFID09Cj4+ Pj4gUEFHRV9TSVpFICovCj4+Pj4gKyAgICBCVUlMRF9CVUdfT04oWEVOX1BBR0VfU0laRSAhPSBQ QUdFX1NJWkUpOwo+Pj4gV2h5IEJVSUxEX0JVR19PTj8gVGhpcyBzaG91bGQgc2ltcGx5IG5vdCBs b2FkIGlmIHBhZ2Ugc2l6ZXMgYXJlCj4+PiBkaWZmZXJlbnQuCj4+Pgo+Pj4gICAgCj4+IFRoaXMg aXMgYSBjb21waWxlIHRpbWUgY2hlY2ssIHNvIGlmIGtlcm5lbC9YZW4gaXMgY29uZmlndXJlZAo+ PiB0byB1c2UgcGFnZSBzaXplIGNvbWJpbmF0aW9uIHdoaWNoIGlzIG5vdCBzdXBwb3J0ZWQgYnkg dGhlCj4+IGRyaXZlciBpdCB3aWxsIGZhaWwgZHVyaW5nIGNvbXBpbGF0aW9uLiBUaGlzIHNlZW1z IGNvcnJlY3QgdG8gbWUsCj4+IGJlY2F1c2UgeW91IHNob3VsZG4ndCBldmVuIHRyeSB0byBsb2Fk IHRoZSBkcml2ZXIgd2hpY2gKPj4gY2Fubm90IGhhbmRsZSBkaWZmZXJlbnQgcGFnZSBzaXplcyB0 byBub3QgbWFrZSBhbnkgaGFybS4KPgo+IFRoaXMgd2lsbCBwcmV2ZW50IHdob2xlIGtlcm5lbCBm cm9tIGJ1aWxkaW5nLiBTbywgZm9yIGV4YW1wbGUsCj4gcmFuZGNvbmZpZyBidWlsZHMgd2lsbCBm YWlsLgo+Cm1ha2VzIGEgbG90IG9mIHNlbnNlLCB0aGFuayB5b3UKd2lsbCByZXdvcmsgc28gSSBy ZWplY3QgdG8gbG9hZCBpZiB0aGUgcmVxdWlyZW1lbnQgaXMgbm90IG1ldAo+Pj4KPj4+Cj4+Pj4g KyAgICByZXQgPSBnbnR0YWJfbWFwX3JlZnMobWFwX29wcywgTlVMTCwgYnVmLT5wYWdlcywgYnVm LT5udW1fcGFnZXMpOwo+Pj4+ICsgICAgQlVHX09OKHJldCk7Cj4+PiBXZSBzaG91bGQgdHJ5IG5v dCB0byBCVUcqKCkuIFRoZXJlIGFyZSBhIGZldyBpbiB0aGlzIHBhdGNoIChhbmQgcG9zc2libHkK Pj4+IG90aGVycykgdGhhdCBJIHRoaW5rIGNhbiBiZSBhdm9pZGVkLgo+Pj4KPj4gSSB3aWxsIHJl d29yayBCVUdfKiBmb3IgbWFwL3VubWFwIGNvZGUgdG8gaGFuZGxlIGVycm9ycywKPj4gYnV0IHdp bGwgc3RpbGwgbGVhdmUKPj4gICAgICAvKiBlaXRoZXIgcGFnZXMgb3Igc2d0LCBub3QgYm90aCAq Lwo+PiAgICAgIEJVR19PTihjZmctPnBhZ2VzICYmIGNmZy0+c2d0KTsKPj4gd2hpY2ggaXMgYSBy ZWFsIGRyaXZlciBidWcgYW5kIG11c3Qgbm90IGhhcHBlbgo+IFdoeSBub3QgcmV0dXJuIGFuIGVy cm9yPwo+Cj4gSW4gZmFjdCwgQUZBSUNTIHlvdSBvbmx5IGNhbGwgaXQgaW4gcGF0Y2ggOSB3aGVy ZSBib3RoIG9mIHRoZXNlIGNhbiBiZQo+IHRlc3RlZCwgaW4gd2hpY2ggY2FzZSBzb21ldGhpbmcg bGlrZSAtRUlOVkFMIHdvdWxkIGxvb2sgcmVhc29uYWJsZS4Kb2ssIHdpbGwgcmVtb3ZlIEJVR19P TiBhcyB3ZWxsCj4gLWJvcmlzCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fXwpkcmktZGV2ZWwgbWFpbGluZyBsaXN0CmRyaS1kZXZlbEBsaXN0cy5mcmVlZGVz a3RvcC5vcmcKaHR0cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9k cmktZGV2ZWwK