linux-kernel - Re: [PATCH 2/2] xhci:prevent "callbacks suppressed" when debug is not enabled

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Date:	Tue, 27 Aug 2013 17:16:37 +0300
From:	Dmitry Kasatkin <d.kasatkin@...sung.com>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
	Sarah Sharp <sarah.a.sharp@...el.com>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] xhci:prevent "callbacks suppressed" when debug is not
 enabled

On 16/08/13 20:45, Greg KH wrote:
> On Fri, Aug 16, 2013 at 08:38:12PM +0300, Dmitry Kasatkin wrote:
>> On Fri, Aug 16, 2013 at 8:30 PM, Sarah Sharp <sarah.a.sharp@...el.com> wrote:
>>> On Fri, Aug 16, 2013 at 10:26:35AM -0700, Sarah Sharp wrote:
>>>> On Thu, Aug 15, 2013 at 05:17:16PM -0700, Greg KH wrote:
>>>>> On Thu, Aug 15, 2013 at 07:04:55PM +0300, Dmitry Kasatkin wrote:
>>>>>> When debug is not enabled and dev_dbg() will expand to nothing,
>>>>>> log might be flooded with "callbacks suppressed". If it was not
>>>>>> done on purpose, better to use dev_dbg_ratelimited() instead.
>>>>>>
>>>>>> Signed-off-by: Dmitry Kasatkin <d.kasatkin@...sung.com>
>>>>>> ---
>>>>>>  drivers/usb/host/xhci-ring.c | 6 ++----
>>>>>>  1 file changed, 2 insertions(+), 4 deletions(-)
>>>>>
>>>>> Sarah, does this patch conflict with the trace debug patches being
>>>>> worked on?  I'll hold off on applying it for now, let me know if it's ok
>>>>> or not.
>>>> It doesn't conflict with the trace debug patches, because those only
>>>> effect debugging with xhci_dbg with the host device, not dev_dbg with
>>>> the USB device.  This should apply fine to usb-next.
>>> At another glance, the patch removes two if blocks, but doesn't
>>> re-indent the rest of the lines:
>>>
>>>> @@ -3060,8 +3060,7 @@ int xhci_queue_intr_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
>>>>        * to set the polling interval (once the API is added).
>>>>        */
>>>>       if (xhci_interval != ep_interval) {
>>>> -             if (printk_ratelimit())
>>>> -                     dev_dbg(&urb->dev->dev, "Driver uses different interval"
>>>> +             dev_dbg_ratelimited(&urb->dev->dev, "Driver uses different interval"
>>>>                                       " (%d microframe%s) than xHCI "
>>>>                                       "(%d microframe%s)\n",
>>>>                                       ep_interval,
>>> That should probably be fixed.
>> It actually looks correct when patch is applied.
>>
>> But it depends what you mean of course.
>> It looks like it was before:
>> dev_dbg_ratelimited(&urb->dev->dev, "Driver uses different interval"
>>                                        " (%d microframe%s) than xHCI "
>>                                        "(%d microframe%s)\n",
>>                                        ep_interval,
>>                                         ep_interval == 1 ? "" : "s",
>>
>> Or may be you mean:
>> dev_dbg_ratelimited(&urb->dev->dev, "Driver uses different interval"
>>                                " (%d microframe%s) than xHCI "
>>                                "(%d microframe%s)\n",
>>                                ep_interval,
>>                                ep_interval == 1 ? "" : "s",
> No, it should look like:
>
> 		dev_dbg_ratelimited(&urb->dev->dev,
> 				    "Driver uses different interval (%d microframe%s) than xHCI (%d microframe%s)\n",
> 				     ep_interval, ep_interval == 1 ? "" : "s",

Hello. Sorry I was distracted so much from the kernel.

But putting string to one line make it much over 80 chars.
Is that considered OK?

- Dmitry

> and the rest of that call indented the same way.
>
> thanks,
>
> greg k-h
>

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