Re: [PATCH] mwifiex: pcie: skip cancel_work_sync() on reset failure path

Kalle Valo
2020-11-10T18:51:45Z

Tsuchiya Yuto <kitakar@gmail.com> wrote:

> If a reset is performed, but even the reset fails for some reasons (e.g.,
> on Surface devices, the fw reset requires another quirks),
> cancel_work_sync() hangs in mwifiex_cleanup_pcie().
>
> # firmware went into a bad state
> [...]
> [ 1608.281690] mwifiex_pcie 0000:03:00.0: info: shutdown mwifiex...
> [ 1608.282724] mwifiex_pcie 0000:03:00.0: rx_pending=0, tx_pending=1, cmd_pending=0
> [ 1608.292400] mwifiex_pcie 0000:03:00.0: PREP_CMD: card is removed
> [ 1608.292405] mwifiex_pcie 0000:03:00.0: PREP_CMD: card is removed
> # reset performed after firmware went into a bad state
> [ 1609.394320] mwifiex_pcie 0000:03:00.0: WLAN FW already running! Skip FW dnld
> [ 1609.394335] mwifiex_pcie 0000:03:00.0: WLAN FW is active
> # but even the reset failed
> [ 1619.499049] mwifiex_pcie 0000:03:00.0: mwifiex_cmd_timeout_func: Timeout cmd id = 0xfa, act = 0xe000
> [ 1619.499094] mwifiex_pcie 0000:03:00.0: num_data_h2c_failure = 0
> [ 1619.499103] mwifiex_pcie 0000:03:00.0: num_cmd_h2c_failure = 0
> [ 1619.499110] mwifiex_pcie 0000:03:00.0: is_cmd_timedout = 1
> [ 1619.499117] mwifiex_pcie 0000:03:00.0: num_tx_timeout = 0
> [ 1619.499124] mwifiex_pcie 0000:03:00.0: last_cmd_index = 0
> [ 1619.499133] mwifiex_pcie 0000:03:00.0: last_cmd_id: fa 00 07 01 07 01 07 01 07 01
> [ 1619.499140] mwifiex_pcie 0000:03:00.0: last_cmd_act: 00 e0 00 00 00 00 00 00 00 00
> [ 1619.499147] mwifiex_pcie 0000:03:00.0: last_cmd_resp_index = 3
> [ 1619.499155] mwifiex_pcie 0000:03:00.0: last_cmd_resp_id: 07 81 07 81 07 81 07 81 07 81
> [ 1619.499162] mwifiex_pcie 0000:03:00.0: last_event_index = 2
> [ 1619.499169] mwifiex_pcie 0000:03:00.0: last_event: 58 00 58 00 58 00 58 00 58 00
> [ 1619.499177] mwifiex_pcie 0000:03:00.0: data_sent=0 cmd_sent=1
> [ 1619.499185] mwifiex_pcie 0000:03:00.0: ps_mode=0 ps_state=0
> [ 1619.499215] mwifiex_pcie 0000:03:00.0: info: _mwifiex_fw_dpc: unregister device
> # mwifiex_pcie_work hang happening
> [ 1823.233923] INFO: task kworker/3:1:44 blocked for more than 122 seconds.
> [ 1823.233932] Tainted: G WC OE 5.10.0-rc1-1-mainline #1
> [ 1823.233935] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 1823.233940] task:kworker/3:1 state:D stack: 0 pid: 44 ppid: 2 flags:0x00004000
> [ 1823.233960] Workqueue: events mwifiex_pcie_work [mwifiex_pcie]
> [ 1823.233965] Call Trace:
> [ 1823.233981] __schedule+0x292/0x820
> [ 1823.233990] schedule+0x45/0xe0
> [ 1823.233995] schedule_timeout+0x11c/0x160
> [ 1823.234003] wait_for_completion+0x9e/0x100
> [ 1823.234012] __flush_work.isra.0+0x156/0x210
> [ 1823.234018] ? flush_workqueue_prep_pwqs+0x130/0x130
> [ 1823.234026] __cancel_work_timer+0x11e/0x1a0
> [ 1823.234035] mwifiex_cleanup_pcie+0x28/0xd0 [mwifiex_pcie]
> [ 1823.234049] mwifiex_free_adapter+0x24/0xe0 [mwifiex]
> [ 1823.234060] _mwifiex_fw_dpc+0x294/0x560 [mwifiex]
> [ 1823.234074] mwifiex_reinit_sw+0x15d/0x300 [mwifiex]
> [ 1823.234080] mwifiex_pcie_reset_done+0x50/0x80 [mwifiex_pcie]
> [ 1823.234087] pci_try_reset_function+0x5c/0x90
> [ 1823.234094] process_one_work+0x1d6/0x3a0
> [ 1823.234100] worker_thread+0x4d/0x3d0
> [ 1823.234107] ? rescuer_thread+0x410/0x410
> [ 1823.234112] kthread+0x142/0x160
> [ 1823.234117] ? __kthread_bind_mask+0x60/0x60
> [ 1823.234124] ret_from_fork+0x22/0x30
> [...]
>
> This is a deadlock caused by calling cancel_work_sync() in
> mwifiex_cleanup_pcie():
>
> - Device resets are done via mwifiex_pcie_card_reset()
> - which schedules card->work to call mwifiex_pcie_card_reset_work()
> - which calls pci_try_reset_function().
> - This leads to mwifiex_pcie_reset_done() be called on the same workqueue,
> which in turn calls
> - mwifiex_reinit_sw() and that calls
> - _mwifiex_fw_dpc().
>
> The problem is now that _mwifiex_fw_dpc() calls mwifiex_free_adapter()
> in case firmware initialization fails. That ends up calling
> mwifiex_cleanup_pcie().
>
> Note that all those calls are still running on the workqueue. So when
> mwifiex_cleanup_pcie() now calls cancel_work_sync(), it's really waiting
> on itself to complete, causing a deadlock.
>
> This commit fixes the deadlock by skipping cancel_work_sync() on a reset
> failure path.
>
> After this commit, when reset fails, the following output is
> expected to be shown:
>
> kernel: mwifiex_pcie 0000:03:00.0: info: _mwifiex_fw_dpc: unregister device
> kernel: mwifiex: Failed to bring up adapter: -5
> kernel: mwifiex_pcie 0000:03:00.0: reinit failed: -5
>
> To reproduce this issue, for example, try putting the root port of wifi
> into D3 (replace "00:1d.3" with your setup).
>
> # put into D3 (root port)
> sudo setpci -v -s 00:1d.3 CAP_PM+4.b=0b
>
> Cc: Maximilian Luz <luzmaximilian@gmail.com>
> Signed-off-by: Tsuchiya Yuto <kitakar@gmail.com>

Patch applied to wireless-drivers-next.git, thanks.

4add4d988f95 mwifiex: pcie: skip cancel_work_sync() on reset failure path

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