On 1/21/19 7:46 AM, Hans Verkuil wrote:
Hi Shuah,
On 12/18/2018 06:59 PM, shuah@xxxxxxxxxx wrote:
From: Shuah Khan <shuah@xxxxxxxxxx>
Media Device Allocator API to allows multiple drivers share a media device.
This API solves a very common use-case for media devices where one physical
device (an USB stick) provides both audio and video. When such media device
exposes a standard USB Audio class, a proprietary Video class, two or more
independent drivers will share a single physical USB bridge. In such cases,
it is necessary to coordinate access to the shared resource.
Using this API, drivers can allocate a media device with the shared struct
device as the key. Once the media device is allocated by a driver, other
drivers can get a reference to it. The media device is released when all
the references are released.
- Tested sharing resources with kaffeine, vlc, xawtv, tvtime, and
arecord. When analog is streaming, digital and audio user-space
applications detect that the tuner is busy and exit. When digital
is streaming, analog and audio applications detect that the tuner is
busy and exit. When arecord is owns the tuner, digital and analog
detect that the tuner is busy and exit.
- Tested media device allocator API with bind/unbind testing on
snd-usb-audio and au0828 drivers to make sure /dev/mediaX is released
only when the last driver is unbound.
- This patch series is tested on 4.20-rc6
- Addressed review comments from Hans on the RFC v8 (rebased on 4.19)
- Updated change log to describe the use-case more clearly.
- No changes to 0001,0002 code since the v7 referenced below.
- 0003 is a new patch to enable ALSA defines that have been
disabled for kernel between 4.9 and 4.19.
- Minor merge conflict resolution in 0004.
- Added SPDX to new files.
References:
https://lkml.org/lkml/2018/11/2/169
https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg105854.html
When I connect my au0828 to my laptop with your v9 patch series applied I get
these warnings:
[ 45.416047] xhci_hcd 0000:39:00.0: xHCI Host Controller
[ 45.417882] xhci_hcd 0000:39:00.0: new USB bus registered, assigned bus number 3
[ 45.419292] xhci_hcd 0000:39:00.0: hcc params 0x200077c1 hci version 0x110 quirks 0x0000000200009810
[ 45.420835] usb usb3: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.00
[ 45.420893] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 45.420899] usb usb3: Product: xHCI Host Controller
[ 45.420905] usb usb3: Manufacturer: Linux 5.0.0-rc1-zen xhci-hcd
[ 45.420911] usb usb3: SerialNumber: 0000:39:00.0
[ 45.424290] hub 3-0:1.0: USB hub found
[ 45.425274] hub 3-0:1.0: 2 ports detected
[ 45.431061] xhci_hcd 0000:39:00.0: xHCI Host Controller
[ 45.432436] xhci_hcd 0000:39:00.0: new USB bus registered, assigned bus number 4
[ 45.432448] xhci_hcd 0000:39:00.0: Host supports USB 3.1 Enhanced SuperSpeed
[ 45.433299] usb usb4: New USB device found, idVendor=1d6b, idProduct=0003, bcdDevice= 5.00
[ 45.433354] usb usb4: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 45.433360] usb usb4: Product: xHCI Host Controller
[ 45.433365] usb usb4: Manufacturer: Linux 5.0.0-rc1-zen xhci-hcd
[ 45.433370] usb usb4: SerialNumber: 0000:39:00.0
[ 45.436134] hub 4-0:1.0: USB hub found
[ 45.436576] hub 4-0:1.0: 2 ports detected
[ 45.750940] usb 3-1: new high-speed USB device number 2 using xhci_hcd
[ 45.899927] usb 3-1: New USB device found, idVendor=2040, idProduct=721e, bcdDevice= 0.05
[ 45.899949] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=10
[ 45.899960] usb 3-1: Product: WinTV Aero-A
[ 45.899970] usb 3-1: Manufacturer: Hauppauge
[ 45.899979] usb 3-1: SerialNumber: 4033622430
[ 46.053476] au0828: au0828 driver loaded
[ 46.053726] WARNING: CPU: 1 PID: 1824 at kernel/module.c:262 module_assert_mutex+0x20/0x30
[ 46.053818] Modules linked in: au0828(+) tveeprom dvb_core v4l2_common rfcomm bnep snd_hda_codec_hdmi snd_hda_codec_realtek
snd_hda_codec_generic uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common videodev media btusb btintel bluetooth
snd_soc_skl snd_soc_skl_ipc snd_soc_sst_ipc snd_soc_sst_dsp snd_soc_acpi_intel_match snd_soc_acpi snd_hda_ext_core x86_pkg_temp_thermal
snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine snd_hda_intel iwlmvm snd_hda_codec snd_hda_core snd_hwdep snd_pcm snd_timer snd iwlwifi
i915 intel_gtt battery ac pcc_cpufreq thermal
[ 46.053853] CPU: 1 PID: 1824 Comm: systemd-udevd Not tainted 5.0.0-rc1-zen #85
[ 46.053856] Hardware name: ASUSTeK COMPUTER INC. UX490UA/UX490UA, BIOS UX490UA.312 04/09/2018
[ 46.053862] RIP: 0010:module_assert_mutex+0x20/0x30
[ 46.053867] Code: 5d c3 e8 f3 68 f5 ff 0f 1f 00 8b 05 d2 5a 7c 01 85 c0 75 01 c3 be ff ff ff ff 48 c7 c7 80 bc 86 82 e8 e4 27 fb ff 85 c0
75 ea <0f> 0b c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 53 48 89 fb e8 c7
[ 46.053871] RSP: 0018:ffffc90002aa3ac8 EFLAGS: 00010246
[ 46.053876] RAX: 0000000000000000 RBX: ffffffffa0573abf RCX: 0000000000000000
[ 46.053880] RDX: 0000000000000000 RSI: ffffffff8286bc80 RDI: ffff8882a517d570
[ 46.053883] RBP: ffff8882880e6000 R08: 0000000000000000 R09: ffff8882b1f5d000
[ 46.053886] R10: 0000000000000001 R11: 0000000000000003 R12: ffffffffa0573abf
[ 46.053890] R13: ffff8882880e60a0 R14: ffff8882880e6000 R15: ffffffffa0577200
[ 46.053894] FS: 00007f0ac7d318c0(0000) GS:ffff8882b6a80000(0000) knlGS:0000000000000000
[ 46.053898] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 46.053902] CR2: 0000560d354ed800 CR3: 00000002880f9003 CR4: 00000000003606e0
[ 46.053905] Call Trace:
[ 46.053910] find_module+0x9/0x20
My .config is available upon request.
Thanks for the config.
Thanks for finding this. find_module() should be called with
module_mutex since 4.15. The media allocator patch was written
before that.
I didn't realize I don't have CONFIG_DEBUG_MUTEXES=y when I switched
to a new system.
I reproduced the problem and re-worked patch 1 and patch 4 in this
series. I will resend the v10 for just those two patches tomorrow.
Please let me know if you want me to send the entire series.
thanks,
-- Shuah
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