linux-kernel - Re: [PATCH 0/4] printk_index: Fix false positives

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Date: Tue, 26 Mar 2024 16:36:30 +0100
From: Petr Mladek <pmladek@...e.com>
To: Geert Uytterhoeven <geert+renesas@...der.be>
Cc: Chris Down <chris@...isdown.name>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Jessica Yu <jeyu@...nel.org>, Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Jason Baron <jbaron@...mai.com>, Jim Cromie <jim.cromie@...il.com>,
	Ilya Dryomov <idryomov@...il.com>, Xiubo Li <xiubli@...hat.com>,
	Jeff Layton <jlayton@...nel.org>, linux-kernel@...r.kernel.org,
	ceph-devel@...r.kernel.org
Subject: Re: [PATCH 0/4] printk_index: Fix false positives

On Tue 2024-03-19 16:09:01, Petr Mladek wrote:
> On Wed 2024-02-28 15:00:01, Geert Uytterhoeven wrote:
> > 	Hi all,
> > 
> > When printk-indexing is enabled, each printk() invocation emits a
> > pi_entry structure, containing the format string and other information
> > related to its location in the kernel sources.  This is even true when
> > the printk() is protected by an always-false check, as is typically the
> > case for debug messages: while the actual code to print the message is
> > optimized out by the compiler, the pi_entry structure is still emitted.
> > Hence when debugging is disabled, this leads to the inclusion in the
> > index of lots of printk formats that cannot be emitted by the current
> > kernel.
> > 
> > This series fixes that for the common debug helpers under include/.
> > It reduces the size of an arm64 defconfig kernel with
> > CONFIG_PRINTK_INDEX=y by ca. 1.5 MiB, or 28% of the overhead of
> > enabling CONFIG_PRINTK_INDEX=y.
> > 
> > Notes:
> >   - netdev_(v)dbg() and netif_(v)dbg() are not affected, as
> >     net{dev,if}_printk() do not implement printk-indexing, except
> >     for the single global internal instance of __netdev_printk().
> >   - This series fixes only debug code in global header files under
> >     include/.  There are more cases to fix in subsystem-specific header
> >     files and in sources files.
> > 
> > Thanks for your comments!
> > 
> > Geert Uytterhoeven (4):
> >   printk: Let no_printk() use _printk()
> >   dev_printk: Add and use dev_no_printk()
> >   dyndbg: Use *no_printk() helpers
> >   ceph: Use no_printk() helper
> > 
> >  include/linux/ceph/ceph_debug.h | 18 +++++++-----------
> >  include/linux/dev_printk.h      | 25 +++++++++++++------------
> >  include/linux/dynamic_debug.h   |  4 ++--
> >  include/linux/printk.h          |  2 +-
> >  4 files changed, 23 insertions(+), 26 deletions(-)
> 
> The whole series looks good to me:
> 
> Reviewed-by: Petr Mladek <pmladek@...e.com>
> 
> I am going take it via printk tree for 6.10.

JFYI, the patchset has been committed into printk/linux.git, branch
for-6.10.

Best Regards,
Petr