Linux-RISC-V Archive on lore.kernel.org
 help / color / Atom feed
From: Dmitry Safonov <dima@arista.com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Juri Lelli <juri.lelli@redhat.com>,
	linux-sh@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Ben Segall <bsegall@google.com>, Guo Ren <guoren@kernel.org>,
	Pavel Machek <pavel@ucw.cz>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Paul Burton <paulburton@kernel.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Mel Gorman <mgorman@suse.de>, Jiri Slaby <jslaby@suse.com>,
	Matt Turner <mattst88@gmail.com>,
	uclinux-h8-devel@lists.sourceforge.jp,
	Len Brown <len.brown@intel.com>,
	linux-pm@vger.kernel.org,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	linux-um@lists.infradead.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Richard Henderson <rth@twiddle.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	linux-kernel@vger.kernel.org, Ralf Baechle <ralf@linux-mips.org>,
	Paul Mackerras <paulus@samba.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-ia64@vger.kernel.org,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	James Hogan <jhogan@kernel.org>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Max Filippov <jcmvbkbc@gmail.com>,
	Vincent Chen <deanbo422@gmail.com>,
	Ingo Molnar <mingo@kernel.org>,
	linux-s390@vger.kernel.org, linux-c6x-dev@linux-c6x.org,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	linux-hexagon@vger.kernel.org, Helge Deller <deller@gmx.de>,
	linux-xtensa@linux-xtensa.org, Vasily Gorbik <gor@linux.ibm.com>,
	Aurelien Jacquiot <jacquiot.aurelien@gmail.com>,
	linux-m68k@lists.linux-m68k.org,
	Stafford Horne <shorne@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	Chris Zankel <chris@zankel.net>, Tony Luck <tony.luck@intel.com>,
	Douglas Anderson <dianders@chromium.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Will Deacon <will@kernel.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Brian Cain <bcain@codeaurora.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	kgdb-bugreport@lists.sourceforge.net,
	linux-snps-arc@lists.infradead.org,
	Fenghua Yu <fenghua.yu@intel.com>, Borislav Petkov <bp@alien8.de>,
	Jeff Dike <jdike@addtoit.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Greentime Hu <green.hu@gmail.com>, Guan Xuetao <gxt@pku.edu.cn>,
	linux-parisc@vger.kernel.org, linux-alpha@vger.kernel.org,
	Ley Foon Tan <lftan@altera.com>,
	"David S. Miller" <davem@davemloft.net>,
	Rich Felker <dalias@libc.org>, Petr Mladek <pmladek@suse.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Jonas Bonn <jonas@southpole.se>,
	Richard Weinberger <richard@nod.at>,
	x86@kernel.org, Russell King <linux@armlinux.org.uk>,
	clang-built-linux@googlegroups.com,
	Ingo Molnar <mingo@redhat.com>, Mark Salter <msalter@redhat.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
	openrisc@lists.librecores.org,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Michal Simek <monstr@monstr.eu>,
	Vineet Gupta <vgupta@synopsys.com>,
	linux-mips@vger.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Jason Wessel <jason.wessel@windriver.com>,
	nios2-dev@lists.rocketboards.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 00/50] Add log level to show_stack()
Date: Wed, 13 Nov 2019 16:40:57 +0000
Message-ID: <578d041a-3ce5-28bb-9fcc-cf90fe82b036@arista.com> (raw)
In-Reply-To: <20191113063334.GA147997@google.com>

Hi Sergey,

On 11/13/19 6:33 AM, Sergey Senozhatsky wrote:
[..]
> Well, here we go. There is a number of generally useful functions that
> print nice data and where people might want to have better loglevel control
> (for debugging purposes). show_stack() is just one of them. Patching all
> those functions, which you have mentioned above, is hardly a fun task to do.
> Hence the printk() per-CPU per-context loglevel proposition. The code there
> is not clever or complicated and is meant for debugging purposes only, but
> with just 3 lines of code one can do some stuff:
> 
> 	/* @BTW you can't do this with "%s" KERN_FOO ;P */
> +	printk_emergency_enter(LOGLEVEL_SCHED);
> +	debug_show_all_locks();
> +	printk_emergency_exit();

Not that I want to critic your proposal more, but just to clarify what
I've meant by "cleaver and complicated":

I don't think semantically there is any difference between:

printk_emergency_enter(LOGLEVEL_SCHED);
printk();
printk_emergency_exit();
vs
printk("%s ...", KERN_SHED, ...);

I was speaking about complexity not about usage, but about realization
inside printk_emergency_enter(): there will be some business logic that
will do "it's NMI? Use loglevel given. it's KERN_ALERT? Don't downgrade
the loglevel..." and other smart details those are really logic which
one have to think about and later maintain.

There will be also minor issues like people inserting print with one log
level and seeing it in dmesg with another, but I presume those
printk_enter() and printk_exit() will cover little amount of code
without much nesting [as long as it's not getting overused]. And also it
can be documented and people will learn about another feature of printk().

And this year I've seen the presentation "Why printk() is so
complicated?" and I presumed that the approach is to keep things as
simple as possible.

In conclusion:
I see that your proposal also solves the problem [except preemption and
some pr_debug() that shouldn't be printed]. And I think your approach is
better in the sense of short-term (we won't have any missed %s KERN_ in
linux-next), but in a long-term it adds some amount of business logic to
printk and another feature.

Just in case: again, I don't mind, it's up to you, maintainers of
printk. It's also not very fun for me to create those patches.
But they fix console_loglevel issues (I hope we could un-export it in
the end) and also I need it for my other patches those will produce
warnings with debug loglevel when configured through sysctl.

Thanks,
          Dmitry

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  parent reply index

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06  3:04 Dmitry Safonov
2019-11-06  3:04 ` [PATCH 01/50] kallsyms/printk: Add loglvl to print_ip_sym() Dmitry Safonov
2019-11-06  4:38   ` Sergey Senozhatsky
2019-11-06 16:39     ` Dmitry Safonov
2019-11-13 15:49   ` Steven Rostedt
2019-11-06  3:05 ` [PATCH 27/50] riscv: Add show_stack_loglvl() Dmitry Safonov
2019-11-06  8:35 ` [PATCH 00/50] Add log level to show_stack() Petr Mladek
2019-11-06 16:12   ` Dmitry Safonov
2019-11-08 10:37   ` Sergey Senozhatsky
2019-11-08 13:04     ` Petr Mladek
2019-11-11  1:23       ` Sergey Senozhatsky
2019-11-11  9:12         ` Petr Mladek
2019-11-12  4:44           ` Sergey Senozhatsky
2019-11-12  4:57             ` Sergey Senozhatsky
2019-11-12  8:35               ` Petr Mladek
2019-11-12 10:12                 ` Sergey Senozhatsky
2019-11-13  1:23                   ` Sergey Senozhatsky
2019-11-13  2:25                     ` Dmitry Safonov
2019-11-13  6:33                       ` Sergey Senozhatsky
2019-11-13  8:47                         ` Petr Mladek
2019-11-13 16:24                           ` Steven Rostedt
2019-11-13 16:40                         ` Dmitry Safonov [this message]
2019-11-15  0:50                           ` Sergey Senozhatsky
2019-11-13 15:32             ` Steven Rostedt
2019-11-11 19:47         ` Dmitry Safonov
2019-11-12  2:17           ` Sergey Senozhatsky
2019-11-12  2:40             ` Dmitry Safonov
2019-11-12  4:25               ` Sergey Senozhatsky
2019-11-13  2:41                 ` Dmitry Safonov
2019-11-13  2:51                   ` Sergey Senozhatsky
2019-11-13 15:39             ` Steven Rostedt
2019-11-15  3:36               ` Sergey Senozhatsky
2019-11-06  9:20 ` Peter Zijlstra
2019-11-06 16:27   ` Dmitry Safonov
2019-11-06 20:34     ` Peter Zijlstra
2019-11-06 23:25       ` Russell King - ARM Linux admin
2019-11-13 15:44         ` Steven Rostedt
2019-11-08 16:28       ` Dmitry Safonov
2019-11-08 17:30         ` Russell King - ARM Linux admin
2019-11-08 21:08           ` Dmitry Safonov
2019-11-13 15:41       ` Steven Rostedt

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=578d041a-3ce5-28bb-9fcc-cf90fe82b036@arista.com \
    --to=dima@arista.com \
    --cc=0x7f454c46@gmail.com \
    --cc=James.Bottomley@HansenPartnership.com \
    --cc=akpm@linux-foundation.org \
    --cc=anton.ivanov@cambridgegreys.com \
    --cc=aou@eecs.berkeley.edu \
    --cc=bcain@codeaurora.org \
    --cc=benh@kernel.crashing.org \
    --cc=borntraeger@de.ibm.com \
    --cc=bp@alien8.de \
    --cc=bsegall@google.com \
    --cc=catalin.marinas@arm.com \
    --cc=chris@zankel.net \
    --cc=clang-built-linux@googlegroups.com \
    --cc=dalias@libc.org \
    --cc=daniel.thompson@linaro.org \
    --cc=davem@davemloft.net \
    --cc=deanbo422@gmail.com \
    --cc=deller@gmx.de \
    --cc=dianders@chromium.org \
    --cc=dietmar.eggemann@arm.com \
    --cc=fenghua.yu@intel.com \
    --cc=geert@linux-m68k.org \
    --cc=gor@linux.ibm.com \
    --cc=green.hu@gmail.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=guoren@kernel.org \
    --cc=gxt@pku.edu.cn \
    --cc=heiko.carstens@de.ibm.com \
    --cc=hpa@zytor.com \
    --cc=ink@jurassic.park.msu.ru \
    --cc=jacquiot.aurelien@gmail.com \
    --cc=jason.wessel@windriver.com \
    --cc=jcmvbkbc@gmail.com \
    --cc=jdike@addtoit.com \
    --cc=jhogan@kernel.org \
    --cc=jonas@southpole.se \
    --cc=jslaby@suse.com \
    --cc=juri.lelli@redhat.com \
    --cc=kgdb-bugreport@lists.sourceforge.net \
    --cc=len.brown@intel.com \
    --cc=lftan@altera.com \
    --cc=linux-alpha@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-c6x-dev@linux-c6x.org \
    --cc=linux-hexagon@vger.kernel.org \
    --cc=linux-ia64@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-m68k@lists.linux-m68k.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=linux-sh@vger.kernel.org \
    --cc=linux-snps-arc@lists.infradead.org \
    --cc=linux-um@lists.infradead.org \
    --cc=linux-xtensa@linux-xtensa.org \
    --cc=linux@armlinux.org.uk \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mattst88@gmail.com \
    --cc=mgorman@suse.de \
    --cc=mingo@kernel.org \
    --cc=mingo@redhat.com \
    --cc=monstr@monstr.eu \
    --cc=mpe@ellerman.id.au \
    --cc=msalter@redhat.com \
    --cc=nios2-dev@lists.rocketboards.org \
    --cc=openrisc@lists.librecores.org \
    --cc=palmer@dabbelt.com \
    --cc=paul.walmsley@sifive.com \
    --cc=paulburton@kernel.org \
    --cc=paulus@samba.org \
    --cc=pavel@ucw.cz \
    --cc=penguin-kernel@I-love.SAKURA.ne.jp \
    --cc=peterz@infradead.org \
    --cc=pmladek@suse.com \
    --cc=ralf@linux-mips.org \
    --cc=richard@nod.at \
    --cc=rjw@rjwysocki.net \
    --cc=rostedt@goodmis.org \
    --cc=rth@twiddle.net \
    --cc=sergey.senozhatsky.work@gmail.com \
    --cc=sergey.senozhatsky@gmail.com \
    --cc=shorne@gmail.com \
    --cc=sparclinux@vger.kernel.org \
    --cc=stefan.kristiansson@saunalahti.fi \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=uclinux-h8-devel@lists.sourceforge.jp \
    --cc=vgupta@synopsys.com \
    --cc=vincent.guittot@linaro.org \
    --cc=will@kernel.org \
    --cc=x86@kernel.org \
    --cc=ysato@users.sourceforge.jp \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-RISC-V Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-riscv/0 linux-riscv/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-riscv linux-riscv/ https://lore.kernel.org/linux-riscv \
		linux-riscv@lists.infradead.org
	public-inbox-index linux-riscv

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-riscv


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git