Hi Marek,
>> 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@xxxxxxxxxxxx>
>> Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>
>
> 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.
can you check latest bluetooth-next. I think that we applied a fix for it.
Regards
Marcel
