From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 12 Nov 2019 13:44:47 +0900 From: Sergey Senozhatsky Subject: Re: [PATCH 00/50] Add log level to show_stack() Message-ID: <20191112044447.GA121272@google.com> References: <20191106030542.868541-1-dima@arista.com> <20191106083538.z5nlpuf64cigxigh@pathway.suse.cz> <20191108103719.GB175344@google.com> <20191108130447.h3wfgo4efjkto56f@pathway.suse.cz> <20191111012336.GA85185@google.com> <20191111091207.u3lrd6cmumnx4czr@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191111091207.u3lrd6cmumnx4czr@pathway.suse.cz> To: Petr Mladek Cc: Sergey Senozhatsky , Dmitry Safonov , linux-kernel@vger.kernel.org, Dmitry Safonov <0x7f454c46@gmail.com>, Andrew Morton , Greg Kroah-Hartman , Ingo Molnar , Jiri Slaby , Sergey Senozhatsky , Steven Rostedt , Tetsuo Handa , Albert Ou , Ben Segall , Dietmar Eggemann , Greentime Hu , Ingo Molnar , James Hogan , Juri Lelli , Mel Gorman , Michal Simek , Palmer Dabbelt , Paul Burton , Paul Walmsley , Peter Zijlstra , Ralf Baechle , Thomas Gleixner , Vincent Chen , Vincent Guittot , Will Deacon , linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org, Ivan Kokshaysky , Matt Turner , Richard Henderson , linux-alpha@vger.kernel.org, Vineet Gupta , linux-snps-arc@lists.infradead.org, Russell King , linux-arm-kernel@lists.infradead.org, clang-built-linux@googlegroups.com, Catalin Marinas , Aurelien Jacquiot , Mark Salter , linux-c6x-dev@linux-c6x.org, Guo Ren , Yoshinori Sato , uclinux-h8-devel@lists.sourceforge.jp, Brian Cain , linux-hexagon@vger.kernel.org, Fenghua Yu , Tony Luck , linux-ia64@vger.kernel.org, Geert Uytterhoeven , linux-m68k@lists.linux-m68k.org, Ley Foon Tan , nios2-dev@lists.rocketboards.org, Jonas Bonn , Stafford Horne , Stefan Kristiansson , openrisc@lists.librecores.org, Helge Deller , "James E.J. Bottomley" , linux-parisc@vger.kernel.org, Benjamin Herrenschmidt , Michael Ellerman , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, Christian Borntraeger , Heiko Carstens , Vasily Gorbik , linux-s390@vger.kernel.org, Rich Felker , linux-sh@vger.kernel.org, "David S. Miller" , sparclinux@vger.kernel.org, Anton Ivanov , Jeff Dike , Richard Weinberger , linux-um@lists.infradead.org, Guan Xuetao , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Len Brown , Pavel Machek , "Rafael J. Wysocki" , linux-pm@vger.kernel.org, Daniel Thompson , Douglas Anderson , Jason Wessel , kgdb-bugreport@lists.sourceforge.net List-ID: On (19/11/11 10:12), Petr Mladek wrote: [..] > > I do recall that we talked about per-CPU printk state bit which would > > start/end "just print it" section. We probably can extend it to "just > > log_store" type of functionality. Doesn't look like a very bad idea. > > The problem with per-CPU printk is that we would need to disable > interrupts. Or disable preemption and have loglevel per-CPU and per-context. preempt_count can navigate us to the right context loglevel on particular CPU. I'm talking here only about backtrace (error) reporting contexts. Those can be atomic perfectly fine. I posted a silly code snippet. [..] > But yes, this per-code-section loglevel is problematic. The feedback > against the patchset shows that people want it also the other way. > I mean to keep pr_debug() as pr_debug(). Hmm. Right. > A solution might be to use the per-code-section loglevel only instead > of some special loglevel. So maybe we can "overwrite" only KERN_DEFAULT loglevels? We certainly should not mess with SCHED or with anything in between EMERG and ERR. > The explicitly passed loglevel makes me feel more confident that > all needed printk() calls were updated. But it might be a false > feeling. I do not really have any strong preference. I'm not like really objecting, just trying to explore some other options. -ss