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Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qdRFQ-005VTZ-0I; Tue, 05 Sep 2023 08:17:20 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qdRFL-005VSg-2m; Tue, 05 Sep 2023 08:17:19 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7D59E60ACE; Tue, 5 Sep 2023 08:17:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7233C433C8; Tue, 5 Sep 2023 08:17:10 +0000 (UTC) Message-ID: <814130d1-8597-d567-ddea-cb82cadea00f@xs4all.nl> Date: Tue, 5 Sep 2023 10:17:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v6 17/18] media: v4l2: Add DELETE_BUFS ioctl Content-Language: en-US, nl To: Benjamin Gaignard , mchehab@kernel.org, tfiga@chromium.org, m.szyprowski@samsung.com, ming.qian@nxp.com, ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de, gregkh@linuxfoundation.org, nicolas.dufresne@collabora.com Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-staging@lists.linux.dev, kernel@collabora.com References: <20230901124414.48497-1-benjamin.gaignard@collabora.com> <20230901124414.48497-18-benjamin.gaignard@collabora.com> From: Hans Verkuil In-Reply-To: <20230901124414.48497-18-benjamin.gaignard@collabora.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230905_011716_007860_325670E4 X-CRM114-Status: GOOD ( 50.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 01/09/2023 14:44, Benjamin Gaignard wrote: > VIDIOC_DELETE_BUFS ioctl allows to delete buffers from a queue. > The number of buffers to delete in given by count field of > struct v4l2_delete_buffers and the range start at the index > specified in the same structure. > > Signed-off-by: Benjamin Gaignard > --- > v6: > - Add lock in vb2_core_delete_buf() > - Fix typo and comments > - Add flags in VIDIOC_DELETE_BUFS decalaration > > .../userspace-api/media/v4l/user-func.rst | 1 + > .../media/v4l/vidioc-delete-bufs.rst | 73 +++++++++++++++++++ > .../media/common/videobuf2/videobuf2-core.c | 24 ++++++ > .../media/common/videobuf2/videobuf2-v4l2.c | 38 +++++++++- > drivers/media/v4l2-core/v4l2-dev.c | 1 + > drivers/media/v4l2-core/v4l2-ioctl.c | 17 +++++ > include/media/v4l2-ioctl.h | 4 + > include/media/videobuf2-core.h | 9 +++ > include/media/videobuf2-v4l2.h | 11 +++ > include/uapi/linux/videodev2.h | 16 ++++ > 10 files changed, 193 insertions(+), 1 deletion(-) > create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst > > diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst > index 15ff0bf7bbe6..3fd567695477 100644 > --- a/Documentation/userspace-api/media/v4l/user-func.rst > +++ b/Documentation/userspace-api/media/v4l/user-func.rst > @@ -17,6 +17,7 @@ Function Reference > vidioc-dbg-g-chip-info > vidioc-dbg-g-register > vidioc-decoder-cmd > + vidioc-delete-bufs > vidioc-dqevent > vidioc-dv-timings-cap > vidioc-encoder-cmd > diff --git a/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst > new file mode 100644 > index 000000000000..a55fe6331fc8 > --- /dev/null > +++ b/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst > @@ -0,0 +1,73 @@ > +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later > +.. c:namespace:: V4L > + > +.. _VIDIOC_DELETE_BUFS: > + > +************************ > +ioctl VIDIOC_DELETE_BUFS > +************************ > + > +Name > +==== > + > +VIDIOC_DELETE_BUFS - Deletes buffers from a queue > + > +Synopsis > +======== > + > +.. c:macro:: VIDIOC_DELETE_BUFs > + > +``int ioctl(int fd, VIDIOC_DELETE_BUFs, struct v4l2_delete_buffers *argp)`` > + > +Arguments > +========= > + > +``fd`` > + File descriptor returned by :c:func:`open()`. > + > +``argp`` > + Pointer to struct :c:type:`v4l2_delete_buffers`. > + > +Description > +=========== > + > +Applications can optionally call the :ref:`VIDIOC_DELETE_BUFS` ioctl to > +delete buffers from a queue. > + > +.. c:type:: v4l2_delete_buffers > + > +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| > + > +.. flat-table:: struct v4l2_delete_buffers > + :header-rows: 0 > + :stub-columns: 0 > + :widths: 1 1 2 > + > + * - __u32 > + - ``index`` > + - The starting buffer index to delete. > + * - __u32 > + - ``count`` > + - The number of buffers to be deleted. That's not quite correct. This function will delete the buffers with indices index until index+count-1. And indices in that range have to be valid buffers, i.e. you can't have already deleted buffers in that range. Or should we allow that? It is a fair question. All buffers also have to be in the DEQUEUED state. The text above suggests that given the following valid indices: 0, 1, 3, 4 (so the buffer with index 2 was already deleted) deleting 2 buffers from index 1 would delete buffers 1, 3. When in fact it will attempt to delete buffers 1 and 2. Also document explicitly that calling this with count=0 (and perhaps index=0 as well?) can be used to check if this ioctl is supported. > + * - __u32 > + - ``type`` > + - Type of the stream or buffers, this is the same as the struct > + :c:type:`v4l2_format` ``type`` field. See > + :c:type:`v4l2_buf_type` for valid values. > + * - __u32 > + - ``reserved``\ [13] > + - A place holder for future extensions. Drivers and applications > + must set the array to zero. What should happen if you delete ALL buffers with this call? I.e., the equivalent to REQBUFS with count=0. Thinking about this the main difference is that DELETE_BUFS can only delete dequeued buffers and it does not stop streaming if all buffers are deleted. So REQBUFS with count=0 (or a STREAMOFF) is still needed to officially stop streaming and cancel the queue. Basically REQBUFS with count=0 is almost the equivalent of calling STREAMOFF followed by DELETE_BUFS for all buffers. Almost, but not quite: REQBUFS(0) also reports if the queue is unbalanced, and it sets q->num_buffers to 0. And in vb2_ioctl_reqbufs it will set vdev->queue->owner to NULL. I am inclined to do the same if DELETE_BUFS deletes all buffers. > + > +Return Value > +============ > + > +On success 0 is returned, on error -1 and the ``errno`` variable is set > +appropriately. The generic error codes are described at the > +:ref:`Generic Error Codes ` chapter. > + > +EBUSY > + File I/O is in progress. > + > +EINVAL > + The buffer ``index`` doesn't exist in the queue. > diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c > index dc7f6b59d237..9edb2a1e95fc 100644 > --- a/drivers/media/common/videobuf2/videobuf2-core.c > +++ b/drivers/media/common/videobuf2/videobuf2-core.c > @@ -1633,6 +1633,30 @@ int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb) > } > EXPORT_SYMBOL_GPL(vb2_core_prepare_buf); > > +int vb2_core_delete_buf(struct vb2_queue *q, struct vb2_buffer *vb) > +{ > + mutex_lock(&q->mmap_lock); > + if (vb->planes[0].mem_priv) > + call_void_vb_qop(vb, buf_cleanup, vb); > + > + /* Free MMAP buffers or release USERPTR buffers */ > + if (q->memory == VB2_MEMORY_MMAP) > + __vb2_buf_mem_free(vb); > + else if (q->memory == VB2_MEMORY_DMABUF) > + __vb2_buf_dmabuf_put(vb); > + else > + __vb2_buf_userptr_put(vb); > + > + vb2_queue_remove_buffer(q, vb); > + mutex_unlock(&q->mmap_lock); > + > + dprintk(q, 2, "buffer %d deleted\n", vb->index); > + kfree(vb); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(vb2_core_delete_buf); This is duplicating what already happens in __vb2_free_mem and __vb2_queue_free. That code needs to be refactored. What you want is a __vb2_delete_buffers(struct vb2_queue *q, unsigned int index, unsigned int buffers) function that is called with mmap_lock held and that deletes buffers in the range 'index' to 'index + count - 1'. Buffers may already be deleted. __vb2_free_mem does almost do all of that already. Then this new function can be called from __vb2_queue_free() and you can make a vb2_core_delete_bufs() function that takes the lock and calls __vb2_delete_buffers. Another note: currently __vb2_queue_free checks if any of the buffers had unbalanced operations. That check needs to be moved to __vb2_delete_buffers as well otherwise that would never be reported when using DELETE_BUFS. > + > /* > * vb2_start_streaming() - Attempt to start streaming. > * @q: videobuf2 queue > diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c > index 8ba658ad9891..d0098f58a65c 100644 > --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c > +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c > @@ -385,7 +385,7 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md > > vb = vb2_get_buffer(q, b->index); > if (!vb) { > - dprintk(q, 1, "%s: buffer is NULL\n", opname); > + dprintk(q, 1, "%s: buffer %u was deleted\n", opname, b->index); > return -EINVAL; > } > > @@ -757,6 +757,42 @@ int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev, > } > EXPORT_SYMBOL_GPL(vb2_prepare_buf); > > +int vb2_delete_bufs(struct vb2_queue *q, struct v4l2_delete_buffers *d) > +{ > + struct vb2_buffer *vb; > + unsigned int index; > + int ret = 0; > + Add: if (!d->count) return 0; (possibly also check if !d->index) > + if (d->index > q->num_buffers || > should be >= here. > + d->count > q->num_buffers || > + (d->index + d->count) > q->num_buffers) { > + return -EINVAL; > + } Once we can delete buffers, how does that change the meaning of num_buffers? Isn't this really max_buffer_index or something similar? But we probably also still need to keep track of the actual number of buffers. And create_bufs still allocated buffers from the last index onwards, it does not attempt to reuse indices of previously deleted buffers. There are a lot of drivers that use num_buffers, they will have to be audited. This needs a lot more thought. > + > + for (index = d->index; index < d->index + d->count; index++) { > + vb = vb2_get_buffer(q, index); > + if (!vb) { > + dprintk(q, 1, "can't find the requested buffer\n"); > + ret = -EINVAL; > + goto error; > + } > + if (vb->state != VB2_BUF_STATE_DEQUEUED) { > + dprintk(q, 1, "can't delete non dequeued buffer index %d\n", vb->index); > + ret = -EINVAL; > + goto error; > + } These checks have to take place first, then, if all is OK, you call vb2_core_delete_bufs. Actually, thinking this over, I would move all these checks to vb2_core_delete_bufs. It can all be put under the mmap_lock mutex to ensure nobody is messing around with the queue while this takes place. Note that when vb2_core_reqbufs() is called with count=0, then if it sees that a buffer is still in use (mmaped), it will log a debug message that the buffers are orphaned. We should keep that, I believe. > + > + ret = vb2_core_delete_buf(q, vb); > + if (ret) > + break; > + } > + > +error: > + d->index = index; I wouldn't do this. I don't think this is useful. > + return ret; > +} > +EXPORT_SYMBOL_GPL(vb2_delete_bufs); > + > int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create) > { > unsigned requested_planes = 1; > diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c > index f81279492682..215654fd6581 100644 > --- a/drivers/media/v4l2-core/v4l2-dev.c > +++ b/drivers/media/v4l2-core/v4l2-dev.c > @@ -720,6 +720,7 @@ static void determine_valid_ioctls(struct video_device *vdev) > SET_VALID_IOCTL(ops, VIDIOC_PREPARE_BUF, vidioc_prepare_buf); > SET_VALID_IOCTL(ops, VIDIOC_STREAMON, vidioc_streamon); > SET_VALID_IOCTL(ops, VIDIOC_STREAMOFF, vidioc_streamoff); > + SET_VALID_IOCTL(ops, VIDIOC_DELETE_BUFS, vidioc_delete_bufs); > } > > if (is_vid || is_vbi || is_meta) { > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > index f4d9d6279094..aac3a0ea0126 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -489,6 +489,13 @@ static void v4l_print_create_buffers(const void *arg, bool write_only) > v4l_print_format(&p->format, write_only); > } > > +static void v4l_print_delete_buffers(const void *arg, bool write_only) > +{ > + const struct v4l2_delete_buffers *p = arg; > + > + pr_cont("index=%d, count=%d\n", p->index, p->count); Use %u since both args are unsigned. > +} > + > static void v4l_print_streamparm(const void *arg, bool write_only) > { > const struct v4l2_streamparm *p = arg; > @@ -2160,6 +2167,15 @@ static int v4l_prepare_buf(const struct v4l2_ioctl_ops *ops, > return ret ? ret : ops->vidioc_prepare_buf(file, fh, b); > } > > +static int v4l_delete_bufs(const struct v4l2_ioctl_ops *ops, > + struct file *file, void *fh, void *arg) > +{ > + struct v4l2_delete_buffers *delete = arg; > + int ret = check_fmt(file, delete->type); > + > + return ret ? ret : ops->vidioc_delete_bufs(file, fh, delete); > +} > + > static int v4l_g_parm(const struct v4l2_ioctl_ops *ops, > struct file *file, void *fh, void *arg) > { > @@ -2909,6 +2925,7 @@ static const struct v4l2_ioctl_info v4l2_ioctls[] = { > IOCTL_INFO(VIDIOC_ENUM_FREQ_BANDS, v4l_enum_freq_bands, v4l_print_freq_band, 0), > IOCTL_INFO(VIDIOC_DBG_G_CHIP_INFO, v4l_dbg_g_chip_info, v4l_print_dbg_chip_info, INFO_FL_CLEAR(v4l2_dbg_chip_info, match)), > IOCTL_INFO(VIDIOC_QUERY_EXT_CTRL, v4l_query_ext_ctrl, v4l_print_query_ext_ctrl, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_query_ext_ctrl, id)), > + IOCTL_INFO(VIDIOC_DELETE_BUFS, v4l_delete_bufs, v4l_print_delete_buffers, INFO_FL_PRIO | INFO_FL_QUEUE | INFO_FL_CLEAR(v4l2_delete_buffers, type)), > }; > #define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls) > > diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h > index edb733f21604..55afbde54211 100644 > --- a/include/media/v4l2-ioctl.h > +++ b/include/media/v4l2-ioctl.h > @@ -163,6 +163,8 @@ struct v4l2_fh; > * :ref:`VIDIOC_CREATE_BUFS ` ioctl > * @vidioc_prepare_buf: pointer to the function that implements > * :ref:`VIDIOC_PREPARE_BUF ` ioctl > + * @vidioc_delete_bufs: pointer to the function that implements > + * :ref:`VIDIOC_DELETE_BUFS ` ioctl > * @vidioc_overlay: pointer to the function that implements > * :ref:`VIDIOC_OVERLAY ` ioctl > * @vidioc_g_fbuf: pointer to the function that implements > @@ -422,6 +424,8 @@ struct v4l2_ioctl_ops { > struct v4l2_create_buffers *b); > int (*vidioc_prepare_buf)(struct file *file, void *fh, > struct v4l2_buffer *b); > + int (*vidioc_delete_bufs)(struct file *file, void *fh, > + struct v4l2_delete_buffers *d); > > int (*vidioc_overlay)(struct file *file, void *fh, unsigned int i); > int (*vidioc_g_fbuf)(struct file *file, void *fh, > diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h > index 97153c69583f..e2c5ff31efd0 100644 > --- a/include/media/videobuf2-core.h > +++ b/include/media/videobuf2-core.h > @@ -843,6 +843,15 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory, > */ > int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb); > > +/** > + * vb2_core_delete_buf() - > + * @q: pointer to &struct vb2_queue with videobuf2 queue. > + * @vb: pointer to struct &vb2_buffer. > + * > + * Return: returns zero on success; an error code otherwise. > + */ > +int vb2_core_delete_buf(struct vb2_queue *q, struct vb2_buffer *vb); > + > /** > * vb2_core_qbuf() - Queue a buffer from userspace > * > diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h > index 5a845887850b..2ef68fdf388f 100644 > --- a/include/media/videobuf2-v4l2.h > +++ b/include/media/videobuf2-v4l2.h > @@ -118,6 +118,17 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create); > */ > int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev, > struct v4l2_buffer *b); > +/** > + * vb2_delete_bufs() - Delete buffers from the queue > + * > + * @q: pointer to &struct vb2_queue with videobuf2 queue. > + * @d: delete parameter, passed from userspace to > + * &v4l2_ioctl_ops->vidioc_delete_bufs handler in driver > + * > + * The return values from this function are intended to be directly returned > + * from &v4l2_ioctl_ops->vidioc_delete_bufs handler in driver. > + */ > +int vb2_delete_bufs(struct vb2_queue *q, struct v4l2_delete_buffers *d); I'm missing the vb2_ioctl_delete_bufs function with a call to vb2_queue_is_busy(). > > /** > * vb2_qbuf() - Queue a buffer from userspace > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index 78260e5d9985..9cc7f570d995 100644 > --- a/include/uapi/linux/videodev2.h > +++ b/include/uapi/linux/videodev2.h > @@ -2616,6 +2616,20 @@ struct v4l2_create_buffers { > __u32 reserved[6]; > }; > > +/** > + * struct v4l2_delete_buffers - VIDIOC_DELETE_BUFS argument > + * @index: the first buffer to be deleted > + * @count: number of buffers to delete > + * @type: enum v4l2_buf_type > + * @reserved: future extensions > + */ > +struct v4l2_delete_buffers { > + __u32 index; > + __u32 count; > + __u32 type; > + __u32 reserved[13]; > +}; > + > /* > * I O C T L C O D E S F O R V I D E O D E V I C E S > * > @@ -2715,6 +2729,8 @@ struct v4l2_create_buffers { > #define VIDIOC_DBG_G_CHIP_INFO _IOWR('V', 102, struct v4l2_dbg_chip_info) > > #define VIDIOC_QUERY_EXT_CTRL _IOWR('V', 103, struct v4l2_query_ext_ctrl) > +#define VIDIOC_DELETE_BUFS _IOWR('V', 104, struct v4l2_delete_buffers) > + > > /* Reminder: when adding new ioctls please add support for them to > drivers/media/v4l2-core/v4l2-compat-ioctl32.c as well! */ You need much more extensive compliance checks for this, esp. mixing create_bufs and delete_bufs. And test it with the test-media test script. Regards, Hans _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel