From patchwork Tue Nov 13 15:06:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philipp Zabel X-Patchwork-Id: 10680905 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1DB1513BF for ; Tue, 13 Nov 2018 15:06:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 07DAF26E74 for ; Tue, 13 Nov 2018 15:06:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EC7372AC37; Tue, 13 Nov 2018 15:06:29 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7136C26E74 for ; Tue, 13 Nov 2018 15:06:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731965AbeKNBFB (ORCPT ); Tue, 13 Nov 2018 20:05:01 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:50699 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731811AbeKNBFB (ORCPT ); Tue, 13 Nov 2018 20:05:01 -0500 Received: from dude.hi.pengutronix.de ([2001:67c:670:100:1d::7] helo=dude.pengutronix.de.) by metis.ext.pengutronix.de with esmtp (Exim 4.89) (envelope-from ) id 1gMaGo-0006uY-QU; Tue, 13 Nov 2018 16:06:26 +0100 From: Philipp Zabel To: linux-media@vger.kernel.org Cc: Hans Verkuil , Mauro Carvalho Chehab , Tomasz Figa , Laurent Pinchart , Nicolas Dufresne Subject: [PATCH] media: vb2: Allow reqbufs(0) with "in use" MMAP buffers Date: Tue, 13 Nov 2018 16:06:21 +0100 Message-Id: <20181113150621.22276-1-p.zabel@pengutronix.de> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::7 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-media@vger.kernel.org Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: John Sheu Videobuf2 presently does not allow VIDIOC_REQBUFS to destroy outstanding buffers if the queue is of type V4L2_MEMORY_MMAP, and if the buffers are considered "in use". This is different behavior than for other memory types and prevents us from deallocating buffers in following two cases: 1) There are outstanding mmap()ed views on the buffer. However even if we put the buffer in reqbufs(0), there will be remaining references, due to vma .open/close() adjusting vb2 buffer refcount appropriately. This means that the buffer will be in fact freed only when the last mmap()ed view is unmapped. 2) Buffer has been exported as a DMABUF. Refcount of the vb2 buffer is managed properly by VB2 DMABUF ops, i.e. incremented on DMABUF get and decremented on DMABUF release. This means that the buffer will be alive until all importers release it. Considering both cases above, there does not seem to be any need to prevent reqbufs(0) operation, because buffer lifetime is already properly managed by both mmap() and DMABUF code paths. Let's remove it and allow userspace freeing the queue (and potentially allocating a new one) even though old buffers might be still in processing. To let userspace know that the kernel now supports orphaning buffers that are still in use, add a new V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS to be set by reqbufs and create_bufs. Signed-off-by: John Sheu Reviewed-by: Pawel Osciak Reviewed-by: Tomasz Figa Signed-off-by: Tomasz Figa [p.zabel@pengutronix.de: moved __vb2_queue_cancel out of the mmap_lock and added V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS] Signed-off-by: Philipp Zabel Acked-by: Sakari Ailus --- .../media/common/videobuf2/videobuf2-core.c | 26 +------------------ .../media/common/videobuf2/videobuf2-v4l2.c | 2 +- include/uapi/linux/videodev2.h | 1 + 3 files changed, 3 insertions(+), 26 deletions(-) diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c index 975ff5669f72..608459450c1e 100644 --- a/drivers/media/common/videobuf2/videobuf2-core.c +++ b/drivers/media/common/videobuf2/videobuf2-core.c @@ -553,20 +553,6 @@ bool vb2_buffer_in_use(struct vb2_queue *q, struct vb2_buffer *vb) } EXPORT_SYMBOL(vb2_buffer_in_use); -/* - * __buffers_in_use() - return true if any buffers on the queue are in use and - * the queue cannot be freed (by the means of REQBUFS(0)) call - */ -static bool __buffers_in_use(struct vb2_queue *q) -{ - unsigned int buffer; - for (buffer = 0; buffer < q->num_buffers; ++buffer) { - if (vb2_buffer_in_use(q, q->bufs[buffer])) - return true; - } - return false; -} - void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb) { call_void_bufop(q, fill_user_buffer, q->bufs[index], pb); @@ -674,23 +660,13 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory, if (*count == 0 || q->num_buffers != 0 || (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) { - /* - * We already have buffers allocated, so first check if they - * are not in use and can be freed. - */ - mutex_lock(&q->mmap_lock); - if (q->memory == VB2_MEMORY_MMAP && __buffers_in_use(q)) { - mutex_unlock(&q->mmap_lock); - dprintk(1, "memory in use, cannot free\n"); - return -EBUSY; - } - /* * Call queue_cancel to clean up any buffers in the * QUEUED state which is possible if buffers were prepared or * queued without ever calling STREAMON. */ __vb2_queue_cancel(q); + mutex_lock(&q->mmap_lock); ret = __vb2_queue_free(q, q->num_buffers); mutex_unlock(&q->mmap_lock); if (ret) diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c index a17033ab2c22..f02d452ceeb9 100644 --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c @@ -624,7 +624,7 @@ EXPORT_SYMBOL(vb2_querybuf); static void fill_buf_caps(struct vb2_queue *q, u32 *caps) { - *caps = 0; + *caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS; if (q->io_modes & VB2_MMAP) *caps |= V4L2_BUF_CAP_SUPPORTS_MMAP; if (q->io_modes & VB2_USERPTR) diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index c8e8ff810190..2a223835214c 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h @@ -879,6 +879,7 @@ struct v4l2_requestbuffers { #define V4L2_BUF_CAP_SUPPORTS_USERPTR (1 << 1) #define V4L2_BUF_CAP_SUPPORTS_DMABUF (1 << 2) #define V4L2_BUF_CAP_SUPPORTS_REQUESTS (1 << 3) +#define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS (1 << 4) /** * struct v4l2_plane - plane info for multi-planar buffers