linux-kernel - Re: [PATCH] Replaced hard coded function names in debug messages with __func_

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Date:   Tue, 3 Nov 2020 21:36:54 +0100
From:   Tabot Kevin <tabot.kevin@...il.com>
To:     Daniel Thompson <daniel.thompson@...aro.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Replaced hard coded function names in debug messages
 with __func__ macro.

On Tue, Nov 03, 2020 at 10:04:40AM +0000, Daniel Thompson wrote:
> On Mon, Nov 02, 2020 at 01:15:56PM +0100, Tabot Kevin wrote:
> > On Mon, Nov 02, 2020 at 09:33:24AM +0000, Daniel Thompson wrote:
> > > On Sat, Oct 31, 2020 at 05:41:03PM +0100, Tabot Kevin wrote:
> > > > This patch fixes the following:
> > > > - Uses __func__ macro to print function names.
> > > > - Got rid of unnecessary braces around single line if statements.
> > > > - End of block comments on a seperate line.
> > > > - A spelling mistake of the word "on".
> > > > 
> > > > Signed-off-by: Tabot Kevin <tabot.kevin@...il.com>
> > > > ---
> > > >  drivers/staging/media/atomisp/i2c/atomisp-ov2680.c | 25 +++++++++++-----------
> > > >  1 file changed, 13 insertions(+), 12 deletions(-)
> > > > 
> > > > diff --git a/drivers/staging/media/atomisp/i2c/atomisp-ov2680.c b/drivers/staging/media/atomisp/i2c/atomisp-ov2680.c
> > > > index c907305..1396a33 100644
> > > > --- a/drivers/staging/media/atomisp/i2c/atomisp-ov2680.c
> > > > +++ b/drivers/staging/media/atomisp/i2c/atomisp-ov2680.c
> > > > @@ -146,7 +146,7 @@ static int ov2680_g_bin_factor_x(struct v4l2_subdev *sd, s32 *val)
> > > >  	struct ov2680_device *dev = to_ov2680_sensor(sd);
> > > >  	struct i2c_client *client = v4l2_get_subdevdata(sd);
> > > >  
> > > > -	dev_dbg(&client->dev,  "++++ov2680_g_bin_factor_x\n");
> > > > +	dev_dbg(&client->dev,  "++++%s\n", __func__);
> > > 
> > > It might be better just to remove this sort of message.
> > > 
> > > They are not "wrong wrong" but are they actually useful one a
> > > driver's basic functions work? Even where they are useful
> > > dynamic techniques (ftrace, tracepoints, etc) arguably provide a
> > > better way to support "did my function actually run" debug
> > > approaches anyway.
> >
> > Thank you very much for the response. So, should I just revert back to
> > the original all the changes in places where I replace hard coded
> > functions names with  __func__?
> 
> [Responses on LKML should be quoted like this rather than top-posted]
> 
> Personally I think it is better to remove them completely from the
> driver rather than revert to the original form. Naturally if Mauro or
> Sakari have strong views on this kind of printed message then you
> need to take that into account but, in general, messages like this
> add little or no value to the driver and can be removed.
> 
I went through the code in an attempt to completely remove all "dev_dbg"
messages, but I noticed not only are there many "dev_dbg" messages, there
are also many such messages like (dev_info, dev_err, etc). Should I
remove them all too?
> 
> > > > @@ -251,8 +251,8 @@ static long __ov2680_set_exposure(struct v4l2_subdev *sd, int coarse_itg,
> > > >  	int ret, exp_val;
> > > >  
> > > >  	dev_dbg(&client->dev,
> > > > -		"+++++++__ov2680_set_exposure coarse_itg %d, gain %d, digitgain %d++\n",
> > > > -		coarse_itg, gain, digitgain);
> > > > +		"+++++++%s coarse_itg %d, gain %d, digitgain %d++\n",
> > > > +		__func__, coarse_itg, gain, digitgain);
> 
> This case is a little less clear cut since the printed message does show
> some elements of internal state. However AFAICT this function just writes
> some state to the hardware so I still take the view that dynamic
> tools (I2C tracepoints for example) provide a better way to debug the
> driver.
> 
> 
> Daniel.