linux-kernel - Re: [PATCH] usb: hcd: initialize hcd->flags to 0 when rm hcd

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Message-ID: <beceb11c-9906-1f12-6da2-0a18801b6c39@ti.com>
Date:   Thu, 12 Jan 2017 17:38:47 +0200
From:   Roger Quadros <rogerq@...com>
To:     Alan Stern <stern@...land.harvard.edu>
CC:     William Wu <william.wu@...k-chips.com>,
        <gregkh@...uxfoundation.org>, <heiko@...ech.de>,
        <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-rockchip@...ts.infradead.org>, <frank.wang@...k-chips.com>,
        <huangtao@...k-chips.com>, <dianders@...gle.com>,
        <groeck@...gle.com>, William wu <wulf@...k-chips.com>
Subject: Re: [PATCH] usb: hcd: initialize hcd->flags to 0 when rm hcd

On 12/01/17 17:33, Alan Stern wrote:
> On Thu, 12 Jan 2017, Roger Quadros wrote:
> 
>> William,
>>
>> On 12/01/17 14:03, William Wu wrote:
>>> From: William wu <wulf@...k-chips.com>
>>>
>>> On some platforms(e.g. rk3399 board), we can call hcd_add/remove
>>> consecutively without calling usb_put_hcd/usb_create_hcd in between,
>>> so hcd->flags can be stale.
>>>
>>> If the HC dies due to whatever reason then without this patch we get
>>> the below error on next hcd_add.
>>>
>>> [173.296154] xhci-hcd xhci-hcd.2.auto: HC died; cleaning up
>>> [173.296209] xhci-hcd xhci-hcd.2.auto: xHCI Host Controller
>>> [173.296762] xhci-hcd xhci-hcd.2.auto: new USB bus registered, assigned bus number 6
>>> [173.296931] usb usb6: We don't know the algorithms for LPM for this host, disabling LPM.
>>> [173.297179] usb usb6: New USB device found, idVendor=1d6b, idProduct=0003
>>> [173.297203] usb usb6: New USB device strings: Mfr=3, Product=2, SerialNumber=1
>>> [173.297222] usb usb6: Product: xHCI Host Controller
>>> [173.297240] usb usb6: Manufacturer: Linux 4.4.21 xhci-hcd
>>> [173.297257] usb usb6: SerialNumber: xhci-hcd.2.auto
>>> [173.298680] hub 6-0:1.0: USB hub found
>>> [173.298749] hub 6-0:1.0: 1 port detected
>>> [173.299382] rockchip-dwc3 usb@...00000: USB HOST connected
>>> [173.395418] hub 5-0:1.0: activate --> -19
>>> [173.603447] irq 228: nobody cared (try booting with the "irqpoll" option)
>>> [173.603493] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.21 #9
>>> [173.603513] Hardware name: Google Kevin (DT)
>>> [173.603531] Call trace:
>>> [173.603568] [<ffffffc0002087dc>] dump_backtrace+0x0/0x160
>>> [173.603596] [<ffffffc00020895c>] show_stack+0x20/0x28
>>> [173.603623] [<ffffffc0004b28a8>] dump_stack+0x90/0xb0
>>> [173.603650] [<ffffffc00027347c>] __report_bad_irq+0x48/0xe8
>>> [173.603674] [<ffffffc0002737cc>] note_interrupt+0x1e8/0x28c
>>> [173.603698] [<ffffffc000270a38>] handle_irq_event_percpu+0x1d4/0x25c
>>> [173.603722] [<ffffffc000270b0c>] handle_irq_event+0x4c/0x7c
>>> [173.603748] [<ffffffc00027456c>] handle_fasteoi_irq+0xb4/0x124
>>> [173.603777] [<ffffffc00026fe3c>] generic_handle_irq+0x30/0x44
>>> [173.603804] [<ffffffc0002701a8>] __handle_domain_irq+0x90/0xbc
>>> [173.603827] [<ffffffc0002006f4>] gic_handle_irq+0xcc/0x188
>>> ...
>>> [173.604500] [<ffffffc000203700>] el1_irq+0x80/0xf8
>>> [173.604530] [<ffffffc000261388>] cpu_startup_entry+0x38/0x3cc
>>> [173.604558] [<ffffffc00090f7d8>] rest_init+0x8c/0x94
>>> [173.604585] [<ffffffc000e009ac>] start_kernel+0x3d0/0x3fc
>>> [173.604607] [<0000000000b16000>] 0xb16000
>>> [173.604622] handlers:
>>> [173.604648] [<ffffffc000642084>] usb_hcd_irq
>>> [173.604673] Disabling IRQ #228
>>>
>>> Signed-off-by: William wu <wulf@...k-chips.com>
>>> Signed-off-by: William wu <william.wu@...k-chips.com>
>>> ---
>>>  drivers/usb/core/hcd.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
>>> index 479e223..612fab6 100644
>>> --- a/drivers/usb/core/hcd.c
>>> +++ b/drivers/usb/core/hcd.c
>>> @@ -3017,6 +3017,7 @@ void usb_remove_hcd(struct usb_hcd *hcd)
>>>  	}
>>>  
>>>  	usb_put_invalidate_rhdev(hcd);
>>> +	hcd->flags = 0;
>>>  }
>>>  EXPORT_SYMBOL_GPL(usb_remove_hcd);
>>>  
>>>
>> I suggest to initialize hcd->flags to 0 in usb_add_hcd() instead.
>>
>> cheers,
>> -roger
> 
> Roger, didn't you originally propose this very same patch in
> 
> 	http://marc.info/?l=linux-usb&m=146556415503583&w=2
> 
> (and of course, the earlier versions before v10)?  What happened to it?

Alan, You are right. That patch got lost in the ML. Looks like I didn't push it hard enough
and then forgot about it. Sorry.

William,

You don't need to do any changes. My earlier version was clearing the flag
in usb_add_hcd() and I guess Alan suggested to move it to usb_remove_hcd().

So your patch is good.
You can add my.

Acked-by: Roger Quadros <rogerq@...com>

cheers,
-roger