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Subject: Re: [PATCH v3] usb:xhci fix panic in
 xhci_free_virt_devices_depth_first
To: Yu Chen <chenyu56@huawei.com>, mathias.nyman@intel.com,
        gregkh@linuxfoundation.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc: fanning4@hisilicon.com, lirui39@hisilicon.com, yangdi10@hisilicon.com,
        wangbinghui@hisilicon.com, groeck@google.com, john.stultz@linaro.org
References: <20171107020138.89251-1-chenyu56@huawei.com>
From: Mathias Nyman <mathias.nyman@linux.intel.com>
Message-ID: <ef197215-cf9c-fd67-69b5-b841dd16a65b@linux.intel.com>
Date: Tue, 7 Nov 2017 16:36:59 +0200
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On 07.11.2017 04:01, Yu Chen wrote:
> From: Yu Chen <chenyu56@huawei.com>
> 
> Check vdev->real_port 0 to avoid panic
> [    9.261347] [<ffffff800884a390>] xhci_free_virt_devices_depth_first+0x58/0x108
> [    9.261352] [<ffffff800884a814>] xhci_mem_cleanup+0x1bc/0x570
> [    9.261355] [<ffffff8008842de8>] xhci_stop+0x140/0x1c8
> [    9.261365] [<ffffff80087ed304>] usb_remove_hcd+0xfc/0x1d0
> [    9.261369] [<ffffff80088551c4>] xhci_plat_remove+0x6c/0xa8
> [    9.261377] [<ffffff80086e928c>] platform_drv_remove+0x2c/0x70
> [    9.261384] [<ffffff80086e6ea0>] __device_release_driver+0x80/0x108
> [    9.261387] [<ffffff80086e7a1c>] device_release_driver+0x2c/0x40
> [    9.261392] [<ffffff80086e5f28>] bus_remove_device+0xe0/0x120
> [    9.261396] [<ffffff80086e2e34>] device_del+0x114/0x210
> [    9.261399] [<ffffff80086e9e00>] platform_device_del+0x30/0xa0
> [    9.261403] [<ffffff8008810bdc>] dwc3_otg_work+0x204/0x488
> [    9.261407] [<ffffff80088133fc>] event_work+0x304/0x5b8
> [    9.261414] [<ffffff80080e31b0>] process_one_work+0x148/0x490
> [    9.261417] [<ffffff80080e3548>] worker_thread+0x50/0x4a0
> [    9.261421] [<ffffff80080e9ea0>] kthread+0xe8/0x100
> [    9.261427] [<ffffff8008083680>] ret_from_fork+0x10/0x50
> 
> The problem can occur if xhci_plat_remove() is called shortly after
> xhci_plat_probe(). While xhci_free_virt_devices_depth_first been
> called before the device has been setup and get real_port initialized.
> The problem occurred on Hikey960 and was reproduced by Guenter Roeck
> on Kevin with chromeos-4.4.
> 
> Cc: Guenter Roeck <groeck@google.com>
> Signed-off-by: Fan Ning <fanning4@hisilicon.com>
> Signed-off-by: Li Rui <lirui39@hisilicon.com>
> Signed-off-by: yangdi <yangdi10@hisilicon.com>
> Signed-off-by: Yu Chen <chenyu56@huawei.com>
> 

Thanks, adding to queue, and adding stable 4.10+ tag as well

-Mathias