Re: Unable to transfer big files to Nokia N9

From: Paul Menzel
Date: Tue Feb 08 2022 - 02:49:50 EST

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Dear Thorsten, dear Luiz,

Am 07.02.22 um 14:14 schrieb Paul Menzel:

Am 28.01.22 um 11:36 schrieb Thorsten Leemhuis:

Hi, this is your Linux kernel regression tracker speaking.

Thorsten, thank you for following up on this.

On 16.01.22 14:27, Paul Menzel wrote:

#regzbot introduced: 81be03e026dc0c16dc1c64e088b2a53b73caa895

thx for getting regzbot involved, much appreciated!

Dear Luiz,

It turns out there was a regression in Linux 5.16-rc1.

@bt-maintaners, what's the status here? Paul reported that over ten days
ago and there wasn't a single reply. Or did the discussion move
somewhere else?

@Paul: just wondering, did you give 5.17-rc1 a try? Might be worth a
shot, if only to confirm the issue is still present.

I just tried with 5.17-rc3, and the issue is still present.

Merging 4840aa67576b (Bluetooth: hci_core: Fix leaking sent_cmd skb) from

https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git

into Linux 5.17-rc3, the resulting Linux kernel also has the problem.

Kind regards,

Paul

Am 20.12.21 um 22:31 schrieb Paul Menzel:

Am 01.12.21 um 23:07 schrieb Paul Menzel:

Am 01.12.21 um 19:29 schrieb Luiz Augusto von Dentz:

On Wed, Dec 1, 2021 at 9:39 AM Paul Menzel <pmenzel@xxxxxxxxxxxxx>
wrote:

For the first time, I wanted to transfer a 2 MB PDF file from a Dell
Latitude E7250 with Debian sid/unstable with Linux 5.16-rc1 to a Nokia
N9 (MeeGo/Harmattan). Using the package *bluez-obexd* 5.61-1 and GNOME
41, the device was found, and paired fine. Then I selected to transfer
the 2 MB file, and after starting for a second, it timed out after the
progress bar moves forward ones and failed.

The systemd journal contains:

       obexd[21139]: Transfer(0x56243fe4f790) Error: Timed out waiting for response

Testing with a a 5 byte test text file, worked fine. Also testing with a
Galaly M32, both files were transferred without problems (though slowly
with 32 KB/s.)

Trying to connect to the device with bluetoothctl failed for me,
and the journal contained, it failed.

       $ bluetoothctl
       Agent registered
       [bluetooth]# connect 40:98:4E:5B:CE:XX
       Attempting to connect to 40:98:4E:5B:CE:XX
       Failed to connect: org.bluez.Error.Failed

       bluetoothd[21104]: src/service.c:btd_service_connect() a2dp-source profile connect failed for 40:98:4E:5B:CE:B3: Protocol not

available

As the Nokia N9 was once pretty popular in the Linux community, I am
pretty sure, it used to work fine in the past, and there is some
regression. It’d be great, if you could give me some hints how to
further debug the issue.

We will need some logs, obexd and btmon, if possible.

I only managed to get the btmon trace [1]. I did `sudo modprobe -r
btusb` and `sudo btmon -w /dev/shm/trace.log`.

Linux messages:

      [29880.100381] calling btusb_driver_init+0x0/0x1000 [btusb] @28716
      [29880.239603] usbcore: registered new interface driver btusb
      [29880.239608] initcall btusb_driver_init+0x0/0x1000 [btusb] returned 0 after 135952 usecs
      [29880.240706] Bluetooth: hci0: unexpected event for opcode 0x0500
      [29880.241598] Bluetooth: hci0: Legacy ROM 2.5 revision 1.0 build 3 week 17 2014
      [29880.241605] Bluetooth: hci0: Intel device is already patched. patch num: 32

  From the system journal:

      Dez 01 22:52:19 ersatz obexd[21139]: Transfer(0x56243fe53dd0) Error: Timed out waiting for response

Were you able to see anything in the attached logs? If the obexd logs
are missing, can you please tell how I should capture them?

I also tested with Ubuntu 20.04 (*linux-image-5.11.0-27-generic*) and
21.10 (*linux-image-5.13.0-19-generic*) live systems booted from a USB
storage device, and transferring `/usr/bin/systemctl`
(`/lib/systemd/systemd`) with size of 1.8 MB worked fine.

Could there be a regression in that area? Unfortunately, it’s not easy
for me to do a bisection on the device at hand.

(Would it be possible to do with QEMU and USB controller and Bluetooth
device passthrough? How can I transfer the file on the command line so
I wouldn’t need to install a desktop environment?)

Turns out, that is indeed possible [2], but turned out to be cumbersome,
as I hit the regression [3], which seems to have been fixed by commit
95655456e7ce (Bluetooth: btintel: Fix broken LED quirk for legacy ROM
devices) merged in the current Linux 5.17 cycle this week.

As a work around, I applied a hunk from Takashi’s patch.

-       { USB_DEVICE(0x8087, 0x0a2a), .driver_info = BTUSB_INTEL_COMBINED },
+       { USB_DEVICE(0x8087, 0x0a2a), .driver_info = BTUSB_INTEL_COMBINED |
+ BTUSB_INTEL_BROKEN_INITIAL_NCMD },

My problem with the Nokia N9 is still present in Linus’ master branch.

Then I built a minimal Linux kernel for QEMU, and ran:

     qemu-system-x86_64 -cpu host -m 2G -enable-kvm \
       -usb -device usb-host,vendorid=0x8087,productid=0x0a2a \
       -drive file=/dev/shm/debian-64.img,format=raw,if=virtio \
       -net nic -net user,hostfwd=tcp::22223-:22 \
       -kernel /dev/shm/bzImage -append "root=/dev/vda1 rw quiet"

In the Debian sid/unstable VM, I used

     ssh root@localhost -p 22223

I once had to pair the VM with the Nokia N9 in bluetoothctl, and then
started `/usr/libexec/bluetooth/obexd`, and ran `obexctl`, and connected
first with `connect`, and then ran `send /lib/systemd/systemd` to
transfer the file. In the problematic cases it stopped/hung after the
first progress message.

     # obexctl
     [NEW] Client /org/bluez/obex
     [obex]# connect 40:98:4E:5B:CE:XX
     Attempting to connect to 40:98:4E:5B:CE:XX
     [NEW] Session /org/bluez/obex/client/session0 [default]
     [NEW] ObjectPush /org/bluez/obex/client/session0
     Connection successful
     [40:98:4E:5B:CE:XX]# send /lib/systemd/systemd
     Attempting to send /lib/systemd/systemd to /org/bluez/obex/client/session0
     [NEW] Transfer /org/bluez/obex/client/session0/transfer0
     Transfer /org/bluez/obex/client/session0/transfer0
         Status: queued
         Name: systemd
         Size: 1841712
         Filename: /lib/systemd/systemd
         Session: /org/bluez/obex/client/session0
     [CHG] Transfer /org/bluez/obex/client/session0/transfer0 Status: active
     [CHG] Transfer /org/bluez/obex/client/session0/transfer0 Transferred: 32737 (@32KB/s 00:55)
     [CHG] Transfer /org/bluez/obex/client/session0/transfer0 Status: error
     [DEL] Transfer /org/bluez/obex/client/session0/transfer0

Some manual bisection of Linux releases, verified, that the regression
was introduced in Linux 5.16-rc1. (Lucky me, I started using Bluetooth
with the Nokia with Linux 5.16-rc1.) Then I verified it was introduced
by the Bluetooth pull request for Linux 5.16. Then I picked commit
81be03e026dc0c16dc1c64e088b2a53b73caa895 due to the commit message, and
bisected from there, and it turns out, that this commit is actually
introducing the regression.

     $ git bisect good
     81be03e026dc0c16dc1c64e088b2a53b73caa895 is the first bad commit
     commit 81be03e026dc0c16dc1c64e088b2a53b73caa895
     Author: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
     Date:   Fri Sep 3 15:27:32 2021 -0700

         Bluetooth: RFCOMM: Replace use of memcpy_from_msg with bt_skb_sendmmsg

         This makes use of bt_skb_sendmmsg instead using memcpy_from_msg which
         is not considered safe to be used when lock_sock is held.

         Also make rfcomm_dlc_send handle skb with fragments and queue them all
         atomically.

         Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
         Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>

      net/bluetooth/rfcomm/core.c | 50 ++++++++++++++++++++++++++++++++++++++-------
      net/bluetooth/rfcomm/sock.c | 46 +++++++++--------------------------------
      2 files changed, 53 insertions(+), 43 deletions(-)

Unfortunately, the patch does not cleanly revert, so users have to wait
until an expert can take a look, and come up with a fix.

Kind regards,

Paul

PS: For the records:

     $ git bisect log
     # bad: [81be03e026dc0c16dc1c64e088b2a53b73caa895] Bluetooth: RFCOMM: Replace use of memcpy_from_msg with bt_skb_sendmmsg
     # good: [49d8a5606428ca0962d09050a5af81461ff90fbb] Bluetooth: fix init and cleanup of sco_conn.timeout_work
     git bisect start '81be03e026dc0' 'HEAD^'
     # good: [904c139a2517191e48f9cb1bb2d611ae59434009] Bluetooth: Add support for msbc coding format
     git bisect good 904c139a2517191e48f9cb1bb2d611ae59434009
     # good: [8bba13b1d08d42e2e8308924fa5c1551a7b2b011] Bluetooth: btintel: Fix incorrect out of memory check
     git bisect good 8bba13b1d08d42e2e8308924fa5c1551a7b2b011
     # good: [38f64f650dc0e44c146ff88d15a7339efa325918] Bluetooth: Add bt_skb_sendmsg helper
     git bisect good 38f64f650dc0e44c146ff88d15a7339efa325918
     # good: [0771cbb3b97d3c1d68eecd7f00055f599954c34e] Bluetooth: SCO: Replace use of memcpy_from_msg with bt_skb_sendmsg
     git bisect good 0771cbb3b97d3c1d68eecd7f00055f599954c34e
     # first bad commit: [81be03e026dc0c16dc1c64e088b2a53b73caa895] Bluetooth: RFCOMM: Replace use of memcpy_from_msg with bt_skb_sendmmsg

Kind regards,

Paul

[1]: https://owww.molgen.mpg.de/~pmenzel/trace.log.7z

[2]: https://lore.kernel.org/linux-bluetooth/5891f0d5-8d51-9da5-7663-718f301490b1@xxxxxxxxxxxxx/T/#u [3]: https://lore.kernel.org/linux-bluetooth/20211202162256.31837-1-tiwai@xxxxxxx/

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