Tsuchiya Yuto <kitakar@xxxxxxxxx> 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@xxxxxxxxx> > Signed-off-by: Tsuchiya Yuto <kitakar@xxxxxxxxx> Patch applied to wireless-drivers-next.git, thanks. 4add4d988f95 mwifiex: pcie: skip cancel_work_sync() on reset failure path -- https://patchwork.kernel.org/project/linux-wireless/patch/20201028142346.18355-1-kitakar@xxxxxxxxx/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
