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

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Date:	Fri, 16 Aug 2013 10:45:16 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Cc:	Sarah Sharp <sarah.a.sharp@...el.com>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	Dmitry Kasatkin <d.kasatkin@...sung.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] xhci:prevent "callbacks suppressed" when debug is
 not enabled

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",

and the rest of that call indented the same way.

thanks,

greg k-h
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