netdev - Re: [PATCH 4/7] usbnet: cdc_mbim: don't recover device if suspend fails in system sleep

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Date:	Tue, 5 Mar 2013 19:07:57 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Kosina <jkosina@...e.cz>,
	Alan Stern <stern@...land.harvard.edu>,
	Oliver Neukum <oneukum@...e.de>, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH 4/7] usbnet: cdc_mbim: don't recover device if suspend
 fails in system sleep

On Tue, Mar 5, 2013 at 3:09 PM, Bjørn Mork <bjorn@...k.no> wrote:
> Ming Lei <ming.lei@...onical.com> writes:
>
>> If suspend callback fails in system sleep context, usb core will
>> ignore the failure and let system sleep go ahead further, so
>> this patch doesn't recover device under this situation.
>>
>> Cc: Bjørn Mork <bjorn@...k.no>
>> Signed-off-by: Ming Lei <ming.lei@...onical.com>
>> ---
>>  drivers/net/usb/cdc_mbim.c |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/usb/cdc_mbim.c b/drivers/net/usb/cdc_mbim.c
>> index 248d2dc..da83546 100644
>> --- a/drivers/net/usb/cdc_mbim.c
>> +++ b/drivers/net/usb/cdc_mbim.c
>> @@ -338,7 +338,7 @@ static int cdc_mbim_suspend(struct usb_interface *intf, pm_message_t message)
>>
>>       if (intf == ctx->control && info->subdriver && info->subdriver->suspend)
>>               ret = info->subdriver->suspend(intf, message);
>> -     if (ret < 0)
>> +     if (ret < 0 && PMSG_IS_AUTO(msg))
>>               usbnet_resume(intf);
>>
>>  error:
>
> NAK. We if the device cannot suspend, then it cannot do suspend halfways

Sorry, what do you mean that the device cannot suspend?  If you mean
usb_suspend_device(), its failure is still ignored, and generally it is OK
since the suspend action is driven by upstream port.

> either. Whether the caller will ignore the error or not, is irrelevant.

Anyway, usbnet_resume() can't be called to submit new URBs in
the failure path of system suspend, so the patch should be correct.


Thanks,
--
Ming Lei
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