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Subject: Re: [PATCH v2 12/14] Bluetooth: Update background scan and report
 device based on advertisement monitors
To:     Marcel Holtmann <marcel@holtmann.org>,
        linux-bluetooth@vger.kernel.org,
        'Linux Samsung SOC' <linux-samsung-soc@vger.kernel.org>,
        Miao-chen Chou <mcchou@chromium.org>,
        Johan Hedberg <johan.hedberg@intel.com>
From:   Marek Szyprowski <m.szyprowski@samsung.com>
Message-ID: <cc9eb868-4f4e-e7a3-d0fb-73c54586e1d1@samsung.com>
Date:   Tue, 30 Jun 2020 00:30:27 +0200
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        <CGME20200629223028eucas1p27b9482456072d7864f7505379885a0b4@eucas1p2.samsung.com>
Sender: linux-bluetooth-owner@vger.kernel.org
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Hi

On 17.06.2020 16:39, Marcel Holtmann wrote:
> From: Miao-chen Chou <mcchou@chromium.org>
>
> This calls hci_update_background_scan() when there is any update on the
> advertisement monitors. If there is at least one advertisement monitor,
> the filtering policy of scan parameters should be 0x00. This also reports
> device found mgmt events if there is at least one monitor.
>
> The following cases were tested with btmgmt advmon-* commands.
> (1) add a ADV monitor and observe that the passive scanning is
> triggered.
> (2) remove the last ADV monitor and observe that the passive scanning is
> terminated.
> (3) with a LE peripheral paired, repeat (1) and observe the passive
> scanning continues.
> (4) with a LE peripheral paired, repeat (2) and observe the passive
> scanning continues.
> (5) with a ADV monitor, suspend/resume the host and observe the passive
> scanning continues.
>
> Signed-off-by: Miao-chen Chou <mcchou@chromium.org>
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This patch landed recently in linux-next as commit 8208f5a9d435 
("Bluetooth: Update background scan and report device based on 
advertisement monitors").

It causes a regression, a kernel oops during system suspend/resume cycle 
on Samsung Exynos5250 based Snow Chromebook:

8<--- cut here ---
Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = 86c149f5
[00000000] *pgd=00000000
Internal error: Oops: 5 [#1] SMP ARM
Modules linked in: cmac cros_ec_sysfs cros_ec_lightbar cros_ec_debugfs 
cros_ec_chardev cros_ec_keyb cros_ec_dev snd_soc_hdmi_codec cros_ec_i2c 
cros_ec snd_soc_snow snd_soc_i2s snd_soc_idma snd_soc_s3c_dma exynosdrm 
analogix_dp exynos_gsc v4l2_mem2mem snd_soc_max98095 snd_soc_core 
ac97_bus snd_pcm_dmaengine snd_pcm snd_timer nxp_ptn3460 snd soundcore 
pwm_samsung spi_s3c64xx cyapatp crc_itu_t mwifiex_sdio mwifiex 
sha256_generic libsha256 sha256_arm btmrvl_sdio btmrvl cfg80211 
bluetooth s5p_mfc governor_simpleondemand videobuf2_dma_contig 
videobuf2_memops videobuf2_v4l2 ecdh_generic ecc videobuf2_common 
videodev phy_exynos_usb2 ohci_exynos panfrost gpu_sched mc s3c2410_wdt 
s5p_sss s5p_cec exynos_rng rtc_s3c i2c_arb_gpio_challenge
CPU: 1 PID: 16 Comm: kworker/1:0 Not tainted 
5.7.0-rc7-02995-g8208f5a9d435 #8564
Hardware name: Samsung Exynos (Flattened Device Tree)
Workqueue: events_freezable mmc_rescan
PC is at __queue_work+0x6c/0x4e8
LR is at __queue_work+0x68/0x4e8
pc : [<c03619d8>]    lr : [<c03619d4>]    psr: 60000093
...
Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c5387d  Table: 6be2406a  DAC: 00000051
Process kworker/1:0 (pid: 16, stack limit = 0xf9898f75)
Stack: (0xee117de0 to 0xee118000)
...
[<c03619d8>] (__queue_work) from [<c0361e94>] (queue_work_on+0x40/0x4c)
[<c0361e94>] (queue_work_on) from [<bf17dd0c>] 
(hci_adv_monitors_clear+0x74/0x90 [bluetooth])
[<bf17dd0c>] (hci_adv_monitors_clear [bluetooth]) from [<bf17e138>] 
(hci_unregister_dev+0x158/0x224 [bluetooth])
[<bf17e138>] (hci_unregister_dev [bluetooth]) from [<bf1d1638>] 
(btmrvl_remove_card+0x58/0x7c [btmrvl])
[<bf1d1638>] (btmrvl_remove_card [btmrvl]) from [<c0d09698>] 
(sdio_bus_remove+0x30/0x11c)
[<c0d09698>] (sdio_bus_remove) from [<c09d534c>] 
(device_release_driver_internal+0xe8/0x1ac)
[<c09d534c>] (device_release_driver_internal) from [<c09d3e18>] 
(bus_remove_device+0xcc/0xf8)
[<c09d3e18>] (bus_remove_device) from [<c09cfa3c>] (device_del+0x15c/0x384)
[<c09cfa3c>] (device_del) from [<c0d098b8>] (sdio_remove_func+0x20/0x34)
[<c0d098b8>] (sdio_remove_func) from [<c0d075bc>] 
(mmc_sdio_remove+0x38/0x64)
[<c0d075bc>] (mmc_sdio_remove) from [<c0d08858>] (mmc_sdio_detect+0x6c/0xf8)
[<c0d08858>] (mmc_sdio_detect) from [<c0cff6f0>] (mmc_rescan+0x1d0/0x42c)
[<c0cff6f0>] (mmc_rescan) from [<c0362454>] (process_one_work+0x178/0x4ac)
[<c0362454>] (process_one_work) from [<c0362b44>] (worker_thread+0x2c/0x530)
[<c0362b44>] (worker_thread) from [<c0368610>] (kthread+0x12c/0x158)
[<c0368610>] (kthread) from [<c03001a8>] (ret_from_fork+0x14/0x2c)
Exception stack(0xee117fb0 to 0xee117ff8)
...
---[ end trace 0ec00d142e0a49cf ]---

This board uses btmrvl_sdio bluetooth driver if that helps. Reverting 
this commit in linux-next 20200629 'fixes' the issue.

I can do more tests if needed on this hardware, just let me know how can 
I help and what to do.

> ---
>   include/net/bluetooth/hci_core.h |  1 +
>   net/bluetooth/hci_core.c         | 13 +++++++++++++
>   net/bluetooth/hci_event.c        |  5 +++--
>   net/bluetooth/hci_request.c      | 17 ++++++++++++++---
>   net/bluetooth/mgmt.c             |  5 ++++-
>   5 files changed, 35 insertions(+), 6 deletions(-)

 > ...

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland