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

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Message-ID: <20130827173908.GE21564@kroah.com>
Date:	Tue, 27 Aug 2013 10:39:08 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Dmitry Kasatkin <d.kasatkin@...sung.com>
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 Tue, Aug 27, 2013 at 05:16:37PM +0300, Dmitry Kasatkin wrote:
> 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?

Yes it is.

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