From: Steven Rostedt <rostedt@goodmis.org>
To: Joe Perches <joe@perches.com>
Cc: Nicolas Boichat <drinkcat@chromium.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
devel@driverdev.osuosl.org, lkml <linux-kernel@vger.kernel.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Douglas Anderson <dianders@chromium.org>,
Guenter Roeck <groeck@chromium.org>
Subject: Re: [PATCH v4 3/3] media: atomisp: Only use trace_printk if allowed
Date: Thu, 20 Aug 2020 22:44:59 -0400 [thread overview]
Message-ID: <20200820224459.0968b9f4@oasis.local.home> (raw)
In-Reply-To: <f9d33bcaa2eda680752205d3c3690cb6bc421730.camel@perches.com>
On Thu, 20 Aug 2020 19:36:19 -0700
Joe Perches <joe@perches.com> wrote:
> On Thu, 2020-08-20 at 21:57 -0400, Steven Rostedt wrote:
> > On Fri, 21 Aug 2020 09:39:19 +0800
> > Nicolas Boichat <drinkcat@chromium.org> wrote:
> []
> > > Some other approaches/ideas:
> > > 1. Filter all lkml messages that contain trace_printk. Already found
> > > 1 instance, and I can easily reply to those with a semi-canned answer,
> > > if I remember to check that filter regularly (not sustainable in the
> > > long run...).
> >
> > Added Joe Perches to the thread.
> >
> > We can update checkpatch.pl to complain about a trace_printk() that it
> > finds in the added code.
>
> Why?
>
> I don't see much value in a trace_printk checkpatch warning.
> tracing is still dependent on CONFIG_TRACING otherwise
> trace_printk is an if (0)
>
> ELI5 please.
>
Because no production code should contain trace_printk(). It should be
deleted before going to Linus. If you have trace_printk() in your code,
you will be greeted by the following banner in your dmesg:
**********************************************************
** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **
** **
** trace_printk() being used. Allocating extra memory. **
** **
** This means that this is a DEBUG kernel and it is **
** unsafe for production use. **
** **
** If you see this message and you are not debugging **
** the kernel, report this immediately to your vendor! **
** **
** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **
**********************************************************
-- Steve
next prev parent reply other threads:[~2020-08-21 2:45 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 9:14 [PATCH v4 1/3, RESEND] media: camss: vfe: Use trace_printk for debugging only Nicolas Boichat
2020-08-20 9:14 ` [PATCH v4 2/3] kernel/trace: Add TRACING_ALLOW_PRINTK config option Nicolas Boichat
2020-08-20 9:14 ` [PATCH v4 3/3] media: atomisp: Only use trace_printk if allowed Nicolas Boichat
2020-08-20 14:23 ` Steven Rostedt
2020-08-21 0:13 ` Nicolas Boichat
2020-08-21 0:36 ` Steven Rostedt
2020-08-21 1:39 ` Nicolas Boichat
2020-08-21 1:57 ` Steven Rostedt
2020-08-21 2:36 ` Joe Perches
2020-08-21 2:42 ` Nicolas Boichat
2020-08-21 2:49 ` Joe Perches
2020-08-21 3:04 ` Steven Rostedt
2020-08-21 3:08 ` Steven Rostedt
2020-08-21 2:44 ` Steven Rostedt [this message]
2020-08-21 2:39 ` Nicolas Boichat
2020-08-21 3:01 ` Steven Rostedt
2020-08-21 12:19 ` Nicolas Boichat
2020-08-21 8:48 ` David Laight
2020-08-21 10:27 ` Nicolas Boichat
2020-08-21 11:32 ` David Laight
2020-08-21 12:07 ` Nicolas Boichat
2020-08-21 12:18 ` David Laight
2020-08-21 12:37 ` Nicolas Boichat
2020-08-20 14:21 ` [PATCH v4 1/3, RESEND] media: camss: vfe: Use trace_printk for debugging only Steven Rostedt
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