From: David Laight <David.Laight@ACULAB.COM>
To: 'Nicolas Boichat' <drinkcat@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>
Cc: "dianders@chromium.org" <dianders@chromium.org>,
"groeck@chromium.org" <groeck@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
"Guilherme G. Piccoli" <gpiccoli@canonical.com>,
Kars Mulder <kerneldev@karsmulder.nl>,
Kees Cook <keescook@chromium.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Thomas Gleixner <tglx@linutronix.de>,
Tiezhu Yang <yangtiezhu@loongson.cn>,
Will Deacon <will@kernel.org>, Yue Hu <huyue2@yulong.com>,
"linux-kbuild@vger.kernel.org" <linux-kbuild@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v5] kernel/trace: Add DISALLOW_TRACE_PRINTK make option
Date: Mon, 24 Aug 2020 08:26:13 +0000 [thread overview]
Message-ID: <3f84781f12424cbfa552981af42dfaf2@AcuMS.aculab.com> (raw)
In-Reply-To: <20200824105852.v5.1.I4feb11d34ce7a0dd5ee2c3327fb5a1a9a646be30@changeid>
From: Nicolas Boichat
> Sent: 24 August 2020 03:59
>
> trace_printk is meant as a debugging tool, and should not be
> compiled into production code without specific debug Kconfig
> options enabled, or source code changes, as indicated by the
> warning that shows up on boot if any trace_printk is called:
> ** 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 DISALLOW_TRACE_PRINTK=1 is passed on the make command
> line, the kernel will generate a build-time error if
> trace_printk is used. We expect distributors to set this
> option for their production kernels.
>
> Note that the code to handle trace_printk is still present,
> so this does not prevent people from compiling out-of-tree
> kernel modules, or BPF programs.
>
> Also, we are not making this a kernel config option as we
> want the developer convenience of being able to reuse a
> production kernel config, add trace_printk for debugging,
> and rebuild, without any config changes.
Since the objective seems to be to ensure there are no
calls to trace_printk() in the git tree, but to allow
them in uncommitted sources. Why not use a config option
and rely on rand-config builds to detect any 'accidental'
commits?
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-08-24 8:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 2:59 [PATCH v5] kernel/trace: Add DISALLOW_TRACE_PRINTK make option Nicolas Boichat
2020-08-24 8:26 ` David Laight [this message]
2020-08-24 13:28 ` Steven Rostedt
2020-08-24 13:42 ` Andy Shevchenko
2020-08-24 18:26 ` Steven Rostedt
2020-08-24 13:30 ` Steven Rostedt
2020-08-25 0:38 ` Nicolas Boichat
2020-08-26 1:39 ` Steven Rostedt
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