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b=GQBFSY6ceaNzgIU3uRpxM5LxA8mXg0czfrHDb7PsTkGFnEmk/iHfhX3+a2yMHDOMF JBLjmHSZGFlZ/Fp8ggARCYJwDeRgAZUW/8ms6ijoMjz+bdporQM3fMNF+icZdLXZqf YeQuQnn2GEAjcC84YRNz6buCHwVgdB39scSWwvRo4+M92SoXoRSgHhnNahJh2XMfWM lS2qedMqH0ZruIfNAgSh2TM2britTzHM3RiDroUi4JXAx1TUAmU+K1EMxI1IAs/vBi tZU4Czom92AXPtC/yF2XdyjWBDik28coouq8iwGtCQ7eAgmr2lsrai8zsW7XrB9dTC Ac3CANgmkkV7Q== Message-ID: <294f4150-cbae-f71b-9804-f985d0b0492a@collabora.com> Date: Tue, 5 Sep 2023 16:28:29 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.0 Subject: Re: [PATCH v6 17/18] media: v4l2: Add DELETE_BUFS ioctl To: Hans Verkuil , 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> <814130d1-8597-d567-ddea-cb82cadea00f@xs4all.nl> Content-Language: en-US From: Benjamin Gaignard In-Reply-To: <814130d1-8597-d567-ddea-cb82cadea00f@xs4all.nl> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230905_072837_642223_EDC30CFB X-CRM114-Status: GOOD ( 59.72 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org Le 05/09/2023 à 10:17, Hans Verkuil a écrit : > 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. I will do that. > >> + * - __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. Unlike REQBUFS DELETE_BUFS can delete buffers while streaming so for me the ownership should not change even if there is no more dequeued buffers. For REQBUFS with count=0 means that the going stream is stopped so we can delete all the buffers while DELETE_BUFS usage is to delete buffers while keeping the stream alive. > >> + >> +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. Loops in __vb2_queue_free() and __vb2_free_mem() try to delete buffers at the end of the queue, I could just modify these functions prototype and loops to start from a given index. That should do the job but have impact on create_bufs (see below) > >> + >> /* >> * 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. Reuse previous indices require to be sure that a range of index is free because create_bufs returns, in index parameter, the starting buffer index. I will add a function to find the first available range and use it in vb2_create_bufs() to change how create->index is set. Hans, sound good for you ? > > 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 >