Re: [PATCH v8 00/53] Add DELETE_BUF ioctl

From: Benjamin Gaignard
Date: Fri Sep 29 2023 - 07:45:14 EST



Le 28/09/2023 à 15:16, Benjamin Gaignard a écrit :

Le 28/09/2023 à 15:04, Hans Verkuil a écrit :
Hi Benjamin,

On 27/09/2023 17:35, Benjamin Gaignard wrote:
Unlike when resolution change on keyframes, dynamic resolution change
on inter frames doesn't allow to do a stream off/on sequence because
it is need to keep all previous references alive to decode inter frames.
This constraint have two main problems:
- more memory consumption.
- more buffers in use.
To solve these issue this series introduce DELETE_BUFS ioctl and remove
the 32 buffers limit per queue.

VP9 conformance tests using fluster give a score of 210/305.
The 24 resize inter tests (vp90-2-21-resize_inter_* files) are ok
but require to use postprocessor.

Kernel branch is available here:
https://gitlab.collabora.com/benjamin.gaignard/for-upstream/-/commits/remove_vb2_queue_limit_v8

GStreamer branch to use DELETE_BUF ioctl and testing dynamic resolution
change is here:
https://gitlab.freedesktop.org/benjamin.gaignard1/gstreamer/-/commits/VP9_drc
I applied patches 1-46 on top of staging and applied patch 1/2 of v4l-utils. I chose
1-46 since those would be the first batch to be merged.

I had to apply a small patch on top, since amphion was still using max_allowed_buffers:

https://git.linuxtv.org/hverkuil/media_tree.git/commit/?h=delbuf&id=fce79aa0239a3a4e5c7634b9b7ffc356057b70b4

With that change everything compiled cleanly.

But running the regression tests (test-media script) failed with a kernel oops:

Buffer ioctls (Input 0):
                 fail: v4l2-test-buffers.cpp(611): q.reqbufs(node, 1)
         test VIDIOC_REQBUFS/CREATE_BUFS/QUERYBUF: FAIL
[   25.309343] general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN
[   25.310067] KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
[   25.310471] CPU: 0 PID: 187 Comm: v4l2-compliance Not tainted 6.6.0-rc3+ #1
[   25.310837] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
[   25.311334] RIP: 0010:__vb2_queue_alloc+0x34c/0xd00 [videobuf2_common]
[   25.311688] Code: 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 0c 07 00 00 49 8b b7 40 01 00 00 44 89 f0 4c 8d 2c c6 41 39 ce 73 18 4c 89 e8 48 c1 e8 03 <80> 3c 18 00 0f 85 d2 08 00 00 49 83 7d 00 00 74 02
0f 0b 4c 89 e8
[   25.312670] RSP: 0018:ffff88810afef930 EFLAGS: 00010212
[   25.312948] RAX: 0000000000000001 RBX: dffffc0000000000 RCX: 0000000000000040
[   25.313331] RDX: ffff88810ce08814 RSI: 0000000000000000 RDI: ffff88810cfb72e0
[   25.313708] RBP: ffff88810ce08800 R08: 0000000000001800 R09: 0000000000000001
[   25.314097] R10: ffffffff91560b0f R11: ffffffff8f40006a R12: ffff88810afefa74
[   25.314470] R13: 0000000000000008 R14: 0000000000000001 R15: ffff88810cfb71a0
[   25.314854] FS:  00007fa524908440(0000) GS:ffff88811aa00000(0000) knlGS:0000000000000000
[   25.315281] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   25.315594] CR2: 0000562855948270 CR3: 0000000109e21000 CR4: 0000000000350ef0
[   25.315982] Call Trace:
[   25.316122]  <TASK>
[   25.316243]  ? die_addr+0x37/0xa0
[   25.316433]  ? exc_general_protection+0x144/0x210
[   25.316693]  ? asm_exc_general_protection+0x22/0x30
[   25.316955]  ? entry_SYSCALL_64_after_hwframe+0x46/0xb0
[   25.317235]  ? __vb2_queue_alloc+0x34c/0xd00 [videobuf2_common]
[   25.317555]  vb2_core_create_bufs+0x5a0/0xce0 [videobuf2_common]
[   25.317879]  ? __vb2_queue_alloc+0xd00/0xd00 [videobuf2_common]
[   25.318213]  vb2_create_bufs+0x680/0x7f0 [videobuf2_v4l2]
[   25.318506]  ? __kasan_kmalloc+0x83/0x90
[   25.318729]  ? __kmalloc+0x5c/0x150
[   25.318924]  ? __video_do_ioctl+0x3a5/0xc20 [videodev]
[   25.319223]  ? __copy_timestamp+0x270/0x270 [videobuf2_v4l2]
[   25.319532]  ? v4l_sanitize_format+0x121/0x340 [videodev]
[   25.319839]  vb2_ioctl_create_bufs+0x280/0x440 [videobuf2_v4l2]
[   25.320162]  ? check_fmt+0x15/0x5e0 [videodev]
[   25.320420]  v4l_create_bufs+0xa8/0x150 [videodev]
[   25.320693]  __video_do_ioctl+0x8d0/0xc20 [videodev]
[   25.320975]  ? v4l_prepare_buf+0xa0/0xa0 [videodev]
[   25.321250]  ? __might_fault+0x112/0x170
[   25.321463]  ? __might_fault+0x112/0x170
[   25.321675]  video_usercopy+0x48c/0xd00 [videodev]
[   25.321949]  ? v4l_prepare_buf+0xa0/0xa0 [videodev]
[   25.322228]  ? v4l_enumstd+0x60/0x60 [videodev]
[   25.322497]  ? selinux_bprm_creds_for_exec+0xa90/0xa90
[   25.322779]  ? rseq_ip_fixup+0x304/0x480
[   25.322995]  ? __up_read+0x10b/0x750
[   25.323201]  ? rseq_get_rseq_cs+0x680/0x680
[   25.323430]  v4l2_ioctl+0x17f/0x1f0 [videodev]
[   25.323689]  __x64_sys_ioctl+0x127/0x190
[   25.323905]  do_syscall_64+0x35/0x80
[   25.324105]  entry_SYSCALL_64_after_hwframe+0x46/0xb0
[   25.324372] RIP: 0033:0x7fa524bf44eb
[   25.324564] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b
04 25 28 00 00
[   25.325533] RSP: 002b:00007ffc888efee0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[   25.325933] RAX: ffffffffffffffda RBX: 00007ffc888f0350 RCX: 00007fa524bf44eb
[   25.326314] RDX: 00007ffc888effb0 RSI: 00000000c100565c RDI: 0000000000000023
[   25.326702] RBP: 00007ffc888f8550 R08: 0000000000000000 R09: 0000000000000001
[   25.327081] R10: 0000000000000016 R11: 0000000000000246 R12: 0000000000000000
[   25.327468] R13: 0000000000000001 R14: 00007ffc888f8010 R15: 00007ffc888f1790
[   25.327852]  </TASK>
[   25.327979] Modules linked in: vivid videobuf2_dma_contig v4l2_tpg v4l2_dv_timings cec videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videodev videobuf2_common mc rc_core
[   25.328835] ---[ end trace 0000000000000000 ]---
[   25.329083] RIP: 0010:__vb2_queue_alloc+0x34c/0xd00 [videobuf2_common]
[   25.329434] Code: 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 0c 07 00 00 49 8b b7 40 01 00 00 44 89 f0 4c 8d 2c c6 41 39 ce 73 18 4c 89 e8 48 c1 e8 03 <80> 3c 18 00 0f 85 d2 08 00 00 49 83 7d 00 00 74 02
0f 0b 4c 89 e8
[   25.330417] RSP: 0018:ffff88810afef930 EFLAGS: 00010212
[   25.330812] RAX: 0000000000000001 RBX: dffffc0000000000 RCX: 0000000000000040
[   25.331194] RDX: ffff88810ce08814 RSI: 0000000000000000 RDI: ffff88810cfb72e0
[   25.331594] RBP: ffff88810ce08800 R08: 0000000000001800 R09: 0000000000000001
[   25.331978] R10: ffffffff91560b0f R11: ffffffff8f40006a R12: ffff88810afefa74
[   25.332360] R13: 0000000000000008 R14: 0000000000000001 R15: ffff88810cfb71a0
[   25.332746] FS:  00007fa524908440(0000) GS:ffff88811aa00000(0000) knlGS:0000000000000000
[   25.333170] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   25.333486] CR2: 0000562855948270 CR3: 0000000109e21000 CR4: 0000000000350ef0
[   25.333861] Kernel panic - not syncing: Fatal exception
[   25.334179] Kernel Offset: 0xbe00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[   25.334748] Rebooting in 30 seconds..

I use the build scripts as described here:

https://lore.kernel.org/linux-media/18989016-6392-a77b-6cf7-1223c9161def@xxxxxxxxx/

I use this command to run the regression tests:

./build.sh -virtme -virtme-utils-path /usr/local/bin none delbuf

(delbuf is the name of my branch)

I don't really want to spend time reviewing this series until this is fixed...

Yes that make sense.
It will work on it and let you now when I had fix it.
Regards,
Benjamin

This patch fix the problem:

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 320f37e46343..0598c1e4e9b5 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -428,6 +428,8 @@ static void vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb, uns
  */
 static void vb2_queue_remove_buffer(struct vb2_buffer *vb)
 {
+    if (vb->vb2_queue->num_buffers)
+        vb->vb2_queue->num_buffers--;
     vb->vb2_queue->bufs[vb->index] = NULL;
     vb->vb2_queue = NULL;
 }
@@ -641,8 +643,8 @@ static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 #endif

     /* Free vb2 buffers */
-    for (i = q->max_num_buffers, buffer = 0; i > 0 && buffer < buffers; i--) {
-        struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
+    for (i = q->max_num_buffers, buffer = 0; i >= 0 && buffer < buffers; i--) {
+        struct vb2_buffer *vb = vb2_get_buffer(q, i);

         if (!vb)
             continue;
@@ -2541,6 +2543,7 @@ void vb2_core_queue_release(struct vb2_queue *q)
     __vb2_queue_free(q, q->max_num_buffers);
     kfree(q->bufs);
     q->bufs = NULL;
+    q->num_buffers = 0;
     mutex_unlock(&q->mmap_lock);
 }
 EXPORT_SYMBOL_GPL(vb2_core_queue_release);

I'm preparing a v9 with this + your patch for Amphion driver:

https://gitlab.collabora.com/benjamin.gaignard/for-upstream/-/commits/remove_vb2_queue_limit_v9

Regards,

Benjamin




Regards,

    Hans

changes in version 8:
- Add V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS and new 'max_buffers' field in v4l2_create_buffers
   structure to report the maximum number of buffers that a queue could allocate.
- Add V4L2_BUF_CAP_SUPPORTS_DELETE_BUFS to indicate that a queue support
   DELETE_BUFS ioctl.
- Make some test drivers use more than 32 buffers and DELETE_BUFS ioctl.
- Fix remarks done by Hans
- Move "media: core: Rework how create_buf index returned value is
   computed" patch to the top of the serie.

changes in version 7:
- Use a bitmap to know which entries are valid in queue bufs array.
   The number of buffers in the queue could must calculated from the
   bitmap so num_buffers becomes useless. This led to add quite few
   patches to remove it from all the drivers.
   Note: despiste my attention I may have miss some calls to
   num_buffers...
- Split patches to make them more readable.
- Run v4l2-compliance with additional delete-bufs tests.
- Run ./test-media -kmemleak vivid and no more failures.
   Note: I had to remove USERPTR streaming test because they to much
   frequentely hit get_framevec bug. It is not related to my series
   since this happens all the time on master branch.
- Fix Hans remarks on v6

changes in version 6:
- Get a patch per driver to use vb2_get_buffer() instead of directly access
   to queue buffers array.
- Add lock in vb2_core_delete_buf()
- Use vb2_buffer instead of index
- Fix various comments
- Change buffer index name to BUFFER_INDEX_MASK
- Stop spamming kernel log with unbalanced counters

changes in version 5:
- Rework offset cookie encoding pattern is n ow the first patch of the
   serie.
- Use static array instead of allocated one for postprocessor buffers.

changes in version 4:
- Stop using Xarray, instead let queues decide about their own maximum
   number of buffer and allocate bufs array given that value.
- Rework offset cookie encoding pattern.
- Change DELETE_BUF to DELETE_BUFS because it now usable for
   range of buffer to be symetrical of CREATE_BUFS.
- Add fixes tags on couple of Verisilicon related patches.
- Be smarter in Verisilicon postprocessor buffers management.
- Rebase on top of v6.4

changes in version 3:
- Use Xarray API to store allocated video buffers.
- No module parameter to limit the number of buffer per queue.
- Use Xarray inside Verisilicon driver to store postprocessor buffers
   and remove VB2_MAX_FRAME limit.
- Allow Versilicon driver to change of resolution while streaming
- Various fixes the Verisilicon VP9 code to improve fluster score.
  changes in version 2:
- Use a dynamic array and not a list to keep trace of allocated buffers.
   Not use IDR interface because it is marked as deprecated in kernel
   documentation.
- Add a module parameter to limit the number of buffer per queue.
- Add DELETE_BUF ioctl and m2m helpers.

Regards,
Benjamin

Benjamin Gaignard (53):
   media: videobuf2: Rework offset 'cookie' encoding pattern
   media: videobuf2: Stop spamming kernel log with all queue counter
   media: videobuf2: Use vb2_buffer instead of index
   media: amphion: Use vb2_get_buffer() instead of directly access to
     buffers array
   media: mediatek: jpeg: Use vb2_get_buffer() instead of directly access
     to buffers array
   media: mediatek: vdec: Remove useless loop
   media: sti: hva: Use vb2_get_buffer() instead of directly access to
     buffers array
   media: visl: Use vb2_get_buffer() instead of directly access to
     buffers array
   media: atomisp: Use vb2_get_buffer() instead of directly access to
     buffers array
   media: dvb-core: Use vb2_get_buffer() instead of directly access to
     buffers array
   media: videobuf2: Access vb2_queue bufs array through helper functions
   media: videobuf2: Be more flexible on the number of queue stored
     buffers
   media: Report the maximum possible number of buffers for the queue
   media: test-drivers: vivid: Increase max supported buffers for capture
     queues
   media: test-drivers: vicodec: Increase max supported capture queue
     buffers
   media: verisilicon: Refactor postprocessor to store more buffers
   media: verisilicon: Store chroma and motion vectors offset
   media: verisilicon: g2: Use common helpers to compute chroma and mv
     offsets
   media: verisilicon: vp9: Allow to change resolution while streaming
   media: Remove duplicated index vs q->num_buffers check
   media: core: Add helper to get queue number of buffers
   media: dvb-core: Do not initialize twice queue num_buffer field
   media: dvb-frontends: rtl2832_srd: Use queue min_buffers_needed field
   media: video-i2c: Set min_buffers_needed to 2
   media: pci: cx18: Set correct value to min_buffers_needed field
   media: pci: dt3155: Remove useless check
   media: pci: netup_unidvb: Remove useless number of buffers check
   media: pci: tw68: Stop direct calls to queue num_buffers field
   media: pci: tw686x: Set min_buffers_needed to 3
   media: amphion: Stop direct calls to queue num_buffers field
   media: coda: Stop direct calls to queue num_buffers field
   media: mediatek: vcodec: Stop direct calls to queue num_buffers field
   media: nxp: Stop direct calls to queue num_buffers field
   media: renesas: Set min_buffers_needed to 16
   media: ti: Use queue min_buffers_needed field to set the min number of
     buffers
   media: verisilicon: Stop direct calls to queue num_buffers field
   media: test-drivers: Stop direct calls to queue num_buffers field
   media: usb: airspy: Set min_buffers_needed to 8
   media: usb: cx231xx: Set min_buffers_needed to CX231XX_MIN_BUF
   media: usb: hackrf: Set min_buffers_needed to 8
   media: usb: usbtv: Set min_buffers_needed to 2
   media: atomisp: Stop direct calls to queue num_buffers field
   media: imx: Stop direct calls to queue num_buffers field
   media: meson: vdec: Stop direct calls to queue num_buffers field
   touchscreen: sur40: Stop direct calls to queue num_buffers field
   sample: v4l: Stop direct calls to queue num_buffers field
   media: cedrus: Stop direct calls to queue num_buffers field
   media: core: Rework how create_buf index returned value is computed
   media: core: Add bitmap manage bufs array entries
   media: core: Free range of buffers
   media: v4l2: Add DELETE_BUFS ioctl
   media: v4l2: Add mem2mem helpers for DELETE_BUFS ioctl
   media: test-drivers: Use helper for DELETE_BUFS ioctl

  .../userspace-api/media/v4l/user-func.rst     |   1 +
  .../media/v4l/vidioc-create-bufs.rst          |   8 +-
  .../media/v4l/vidioc-delete-bufs.rst          |  80 +++
  .../media/v4l/vidioc-reqbufs.rst              |   2 +
  drivers/input/touchscreen/sur40.c             |   5 +-
  .../media/common/videobuf2/videobuf2-core.c   | 556 +++++++++++-------
  .../media/common/videobuf2/videobuf2-v4l2.c   | 121 +++-
  drivers/media/dvb-core/dvb_vb2.c              |  17 +-
  drivers/media/dvb-frontends/rtl2832_sdr.c     |   9 +-
  drivers/media/i2c/video-i2c.c                 |   5 +-
  drivers/media/pci/cx18/cx18-streams.c         |  13 +-
  drivers/media/pci/dt3155/dt3155.c             |   2 -
  .../pci/netup_unidvb/netup_unidvb_core.c      |   4 +-
  drivers/media/pci/tw68/tw68-video.c           |   6 +-
  drivers/media/pci/tw686x/tw686x-video.c       |  13 +-
  drivers/media/platform/amphion/vpu_dbg.c      |  30 +-
  drivers/media/platform/amphion/vpu_v4l2.c     |   4 +-
  .../media/platform/chips-media/coda-common.c  |   2 +-
  .../platform/mediatek/jpeg/mtk_jpeg_core.c    |   7 +-
  .../vcodec/decoder/vdec/vdec_vp9_req_lat_if.c |   9 +-
  .../mediatek/vcodec/encoder/mtk_vcodec_enc.c  |   2 +-
  drivers/media/platform/nxp/imx7-media-csi.c   |   7 +-
  drivers/media/platform/renesas/rcar_drif.c    |   8 +-
  drivers/media/platform/st/sti/hva/hva-v4l2.c  |   9 +-
  .../media/platform/ti/am437x/am437x-vpfe.c    |   7 +-
  drivers/media/platform/ti/cal/cal-video.c     |   5 +-
  .../media/platform/ti/davinci/vpif_capture.c  |   5 +-
  .../media/platform/ti/davinci/vpif_display.c  |   5 +-
  drivers/media/platform/ti/omap/omap_vout.c    |   5 +-
  drivers/media/platform/verisilicon/hantro.h   |   9 +-
  .../media/platform/verisilicon/hantro_drv.c   |   5 +-
  .../media/platform/verisilicon/hantro_g2.c    |  14 +
  .../platform/verisilicon/hantro_g2_hevc_dec.c |  18 +-
  .../platform/verisilicon/hantro_g2_vp9_dec.c  |  28 +-
  .../media/platform/verisilicon/hantro_hw.h    |   7 +-
  .../platform/verisilicon/hantro_postproc.c    |  93 ++-
  .../media/platform/verisilicon/hantro_v4l2.c  |  27 +-
  .../media/test-drivers/vicodec/vicodec-core.c |   3 +
  drivers/media/test-drivers/vim2m.c            |   2 +
  .../media/test-drivers/vimc/vimc-capture.c    |   2 +
  drivers/media/test-drivers/visl/visl-dec.c    |  32 +-
  drivers/media/test-drivers/visl/visl-video.c  |   2 +
  drivers/media/test-drivers/vivid/vivid-core.c |  14 +
  .../media/test-drivers/vivid/vivid-meta-cap.c |   3 -
  .../media/test-drivers/vivid/vivid-meta-out.c |   5 +-
  .../test-drivers/vivid/vivid-touch-cap.c      |   5 +-
  .../media/test-drivers/vivid/vivid-vbi-cap.c  |   5 +-
  .../media/test-drivers/vivid/vivid-vbi-out.c  |   5 +-
  .../media/test-drivers/vivid/vivid-vid-cap.c  |   5 +-
  .../media/test-drivers/vivid/vivid-vid-out.c  |   5 +-
  drivers/media/usb/airspy/airspy.c             |   9 +-
  drivers/media/usb/cx231xx/cx231xx-417.c       |   4 +-
  drivers/media/usb/cx231xx/cx231xx-video.c     |   4 +-
  drivers/media/usb/hackrf/hackrf.c             |   9 +-
  drivers/media/usb/usbtv/usbtv-video.c         |   3 +-
  drivers/media/v4l2-core/v4l2-dev.c            |   1 +
  drivers/media/v4l2-core/v4l2-ioctl.c          |  21 +-
  drivers/media/v4l2-core/v4l2-mem2mem.c        |  20 +
  .../staging/media/atomisp/pci/atomisp_ioctl.c |   4 +-
  drivers/staging/media/imx/imx-media-capture.c |   7 +-
  drivers/staging/media/meson/vdec/vdec.c       |  13 +-
  .../staging/media/sunxi/cedrus/cedrus_h264.c  |   8 +-
  .../staging/media/sunxi/cedrus/cedrus_h265.c  |   9 +-
  include/media/v4l2-ioctl.h                    |   4 +
  include/media/v4l2-mem2mem.h                  |  12 +
  include/media/videobuf2-core.h                |  65 +-
  include/media/videobuf2-v4l2.h                |  13 +
  include/uapi/linux/videodev2.h                |  24 +-
  samples/v4l/v4l2-pci-skeleton.c               |   5 +-
  69 files changed, 969 insertions(+), 502 deletions(-)
  create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst

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