From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755896AbcBCOj1 (ORCPT ); Wed, 3 Feb 2016 09:39:27 -0500 Received: from mga04.intel.com ([192.55.52.120]:6892 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755771AbcBCOj0 (ORCPT ); Wed, 3 Feb 2016 09:39:26 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,391,1449561600"; d="scan'208";a="41727025" Subject: Re: [PATCH v3 06/11] staging/android: turn fence_info into a __u64 pointer To: Gustavo Padovan , Greg Kroah-Hartman References: <1454505940-18094-1-git-send-email-gustavo@padovan.org> <1454505940-18094-7-git-send-email-gustavo@padovan.org> Cc: linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, dri-devel@lists.freedesktop.org, Daniel Stone , =?UTF-8?Q?Arve_Hj=c3=b8nnev=c3=a5g?= , Riley Andrews , Daniel Vetter , Rob Clark , Greg Hackmann , John Harrison , Gustavo Padovan From: Maarten Lankhorst Message-ID: <56B2111A.8080103@linux.intel.com> Date: Wed, 3 Feb 2016 15:39:22 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <1454505940-18094-7-git-send-email-gustavo@padovan.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Op 03-02-16 om 14:25 schreef Gustavo Padovan: > From: Gustavo Padovan > > Turn sync_fence_info into __u64 type enable us to extend the struct in the > future without breaking the ABI. > > v2: use type __u64 for fence_info > > v3: fix commit message to reflect the v2 change > > Signed-off-by: Gustavo Padovan > --- > drivers/staging/android/sync.c | 2 +- > drivers/staging/android/uapi/sync.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c > index 2ab0c20..8425457 100644 > --- a/drivers/staging/android/sync.c > +++ b/drivers/staging/android/sync.c > @@ -525,7 +525,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file, > if (info->status >= 0) > info->status = !info->status; > > - len = sizeof(struct sync_file_info); > + len = sizeof(struct sync_file_info) - sizeof(__u64); > > for (i = 0; i < sync_file->num_fences; ++i) { > struct fence *fence = sync_file->cbs[i].fence; > diff --git a/drivers/staging/android/uapi/sync.h b/drivers/staging/android/uapi/sync.h > index a0cf357..e649953 100644 > --- a/drivers/staging/android/uapi/sync.h > +++ b/drivers/staging/android/uapi/sync.h > @@ -54,7 +54,7 @@ struct sync_file_info { > char name[32]; > __s32 status; > > - __u8 sync_fence_info[0]; > + __u64 sync_fence_info; > }; > > #define SYNC_IOC_MAGIC '>' This still doesn't do what you expect it to. I think this is what you want is for userspace to do: struct sync_file_info info; info.flags = info.num_fences = 0; ioctl(fd, SYNC_IOC_FENCE_INFO, &info); if (info.num_fences) { info.sync_fence_info = (uintptr)kcalloc(info.num_fences, sizeof(struct sync_fence_info)); ioctl(fd, SYNC_IOC_FENCE_INFO, &info); } Maybe userspace could preallocate the max in advance and set num_fences higher, kernel would do something like: num_fences = min(info.num_fences, sync->num_fences); struct sync_fence_info array[num_fences]; info.num_fences = sync->num_fences; if (num_fences && copy_to_user((void * __user)(unsigned long)info.sync_fence_info, array, num_fences * sizeof(array))) return -EFAULT;