linux-kernel - Re: [PATCH] media: atomisp: ov2722: replace hardcoded function name

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Date:   Wed, 06 Jan 2021 10:25:26 -0800
From:   Joe Perches <joe@...ches.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Filip Kolev <fil.kolev@...il.com>
Cc:     devel@...verdev.osuosl.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        linux-media@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] media: atomisp: ov2722: replace hardcoded function name

On Wed, 2021-01-06 at 18:52 +0100, Greg Kroah-Hartman wrote:
> On Wed, Jan 06, 2021 at 07:43:42PM +0200, Filip Kolev wrote: 
> > On 06-Jan-21 09:51, Greg Kroah-Hartman wrote:
> > > On Tue, Jan 05, 2021 at 10:29:18PM +0200, Filip Kolev wrote:
> > > > There is a debug message using hardcoded function name instead of the
> > > > __func__ macro. Replace it.
> > > > 
> > > > Report from checkpatch.pl on the file:
> > > > 
> > > > WARNING: Prefer using '"%s...", __func__' to using 'ov2722_remove', this function's name, in a string
> > > > +	dev_dbg(&client->dev, "ov2722_remove...\n");
[]
> > > > diff --git a/drivers/staging/media/atomisp/i2c/atomisp-ov2722.c b/drivers/staging/media/atomisp/i2c/atomisp-ov2722.c
[]
> > > > @@ -1175,7 +1175,7 @@ static int ov2722_remove(struct i2c_client *client)
> > > >   	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > > >   	struct ov2722_device *dev = to_ov2722_sensor(sd);
> > > > -	dev_dbg(&client->dev, "ov2722_remove...\n");
> > > > +	dev_dbg(&client->dev, "%s...\n", __func__);
> > > 
> > > dev_dbg() provides the function name already, and this is just a "trace"
> > > call, and ftrace should be used instead, so the whole line should be
> > > removed entirely.
> > 
> > Thank you for the review!
> > 
> > How do I go about this? Do I amend the patch and re-send as v2 or create a
> > new patch entirely?
> 
> New patch entirely please.

There are quite a lot of these relatively useless function tracing like
uses in the kernel:

$ git grep -P '"%s[\.\!]*\\n"\s*,\s*__func__\s*\)' | wc -l
1065

Perhaps yet another checkpatch warning would be useful:
---
 scripts/checkpatch.pl | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e6857bdfcb2d..46b8ec8fe9e1 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5981,6 +5981,14 @@ sub process {
 			     "Prefer using '\"%s...\", __func__' to using '$context_function', this function's name, in a string\n" . $herecurr);
 		}
 
+# check for unnecessary function tracing like uses
+		if ($rawline =~ /^\+\s*$logFunctions\s*\([^"]*"%s[\.\!]*\\n"\s*,\s*__func__\s*\)\s*;\s*$/) {
+			if (WARN("TRACING_LOGGING",
+				 "Unnecessary ftrace-like logging - prefer using ftrace\n" . $herecurr) &&
+			    $fix) {
+                                fix_delete_line($fixlinenr, $rawline);
+			}
+		}
 # check for spaces before a quoted newline
 		if ($rawline =~ /^.*\".*\s\\n/) {
 			if (WARN("QUOTED_WHITESPACE_BEFORE_NEWLINE",