linux-kernel - Re: [PATCH] Input - elantech: fix debug dump of the current packet

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Message-ID: <1469731797.3998.69.camel@perches.com>
Date:	Thu, 28 Jul 2016 11:49:57 -0700
From:	Joe Perches <joe@...ches.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Benjamin Tissoires <benjamin.tissoires@...hat.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input - elantech: fix debug dump of the current packet

On Thu, 2016-07-28 at 11:40 -0700, Dmitry Torokhov wrote:
> On Thu, Jul 28, 2016 at 11:30:56AM -0700, Joe Perches wrote:
> > 
> > On Thu, 2016-07-28 at 11:58 +0200, Benjamin Tissoires wrote:
> > > 
> > > The use of mixed psmouse_printk() and printk creates 2 lines in the log,
> > > while the use of %*ph solves everything.
> > > 
> > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> > > ---
> > >  drivers/input/mouse/elantech.c | 8 ++------
> > >  1 file changed, 2 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
> > > index 615d23e..3461d04 100644
> > > --- a/drivers/input/mouse/elantech.c
> > > +++ b/drivers/input/mouse/elantech.c
> > > @@ -222,12 +222,8 @@ static int elantech_write_reg(struct psmouse *psmouse, unsigned char reg,
> > >   */
> > >  static void elantech_packet_dump(struct psmouse *psmouse)
> > >  {
> > > -	int	i;
> > > -
> > > -	psmouse_printk(KERN_DEBUG, psmouse, "PS/2 packet [");
> > > -	for (i = 0; i < psmouse->pktsize; i++)
> > > -		printk("%s0x%02x ", i ? ", " : " ", psmouse->packet[i]);
> > > -	printk("]\n");
> > > +	psmouse_printk(KERN_DEBUG, psmouse, "PS/2 packet [%*ph]",
> > > +		       psmouse->pktsize, psmouse->packet);
> > >  }
> > >  
> > >  /*
> > This should add a newline "\n" format termination but
> I added it, thanks for alerting me.
> 
> > 
> > how does the original produce multiple lines of output?
> > 
> > It looks more like psmouse_printk should be removed altogether
> > and dev_debug should be used instead.
> That does not produce output by default whereas elantech driver uses
> elantech_packet_dump() to drop unexpected packets.

So use dev_printk(KERN_DEBUG, etc...


But I still don't see a mechanism for the original code to be
emitted on multiple lines.

How long is the longest packet?

This might truncate it.

Should this be ratelimited?