Re: [PATCH V3] media: stk1160: Fixed high volume of stk1160_dbg messages

[Greg KH <gregkh@linuxfoundation.org>]

On Sat, Nov 25, 2023 at 01:51:35PM +0530, Ghanshyam Agrawal wrote:
> On Sat, Nov 25, 2023 at 1:18 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Sat, Nov 25, 2023 at 01:07:38PM +0530, Ghanshyam Agrawal wrote:
> > > The function stk1160_dbg gets called too many times, which causes
> > > the output to get flooded with messages. Since stk1160_dbg uses
> > > printk, it is now replaced with printk_ratelimited directly.
> > >
> > > Suggested-by: Phillip Potter <phil@philpotter.co.uk>
> > > Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@gmail.com>
> > > ---
> > > V3:
> > > Fixed the issue with my patch needing previous versions being applied
> > > first.
> > >
> > > Used printk_ratelimited instead of dev_warn_ratelimited because
> > > of compiler error "incompatible pointer type".
> > >
> > > V2:
> > > To add KERN_WARNING in printk_ratelimited, and later as per warning by
> > > the checkpatch script, replaced  printk_ratelimited with
> > > dev_warn_ratelimited.
> > >
> > > V1:
> > > The function stk1160_dbg gets called too many times, which causes
> > > the output to get flooded with messages. Since stk1160_dbg uses
> > > printk, it is now replaced with dev_warn_ratelimited.
> > >
> > >  drivers/media/usb/stk1160/stk1160-video.c | 5 ++---
> > >  1 file changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/media/usb/stk1160/stk1160-video.c b/drivers/media/usb/stk1160/stk1160-video.c
> > > index 4e966f6bf608..98417fa31d70 100644
> > > --- a/drivers/media/usb/stk1160/stk1160-video.c
> > > +++ b/drivers/media/usb/stk1160/stk1160-video.c
> > > @@ -107,8 +107,7 @@ void stk1160_copy_video(struct stk1160 *dev, u8 *src, int len)
> > >
> > >       /*
> > >        * TODO: These stk1160_dbg are very spammy!
> > > -      * We should 1) check why we are getting them
> > > -      * and 2) add ratelimit.
> > > +      * We should check why we are getting them.
> > >        *
> > >        * UPDATE: One of the reasons (the only one?) for getting these
> > >        * is incorrect standard (mismatch between expected and configured).
> > > @@ -151,7 +150,7 @@ void stk1160_copy_video(struct stk1160 *dev, u8 *src, int len)
> > >
> > >       /* Let the bug hunt begin! sanity checks! */
> > >       if (lencopy < 0) {
> > > -             stk1160_dbg("copy skipped: negative lencopy\n");
> > > +             printk_ratelimited(KERN_WARNING "copy skipped: negative lencopy\n");
> >
> > You changed a debug message level to a KERN_WARNING level?  That feels
> > like a step backwards.
> >
> > thanks,
> >
> > greg k-h
> 
> Hi Greg,
> 
> Thanks for your response. The log level should indeed be DEBUG
> as it was earlier.
> 
> I only wanted to add a rate limit there because it was printing too
> many log messages as mentioned in the todo. Shall I update the
> log level  to DEBUG and resend the patch? Thank you very much
> again.

If it's spamming the logs, why print anything at all as obviously
everyone is ignoring it?  But I do not really know, the final decision
should be up to the developer and maintainer of this subsystem.

thanks,

greg k-h