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Tue, 12 Nov 2019 18:25:41 -0800 (PST) Subject: Re: [PATCH 00/50] Add log level to show_stack() To: Sergey Senozhatsky , Petr Mladek , Steven Rostedt 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> <20191112044447.GA121272@google.com> <20191112045704.GA138013@google.com> <20191112083509.gmgjpkjffsfaw5lm@pathway.suse.cz> <20191112101229.GA201294@google.com> <20191113012337.GA70781@google.com> From: Dmitry Safonov Message-ID: <25ff45f0-6420-f660-55a8-637f11ab5ab4@arista.com> Date: Wed, 13 Nov 2019 02:25:15 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191113012337.GA70781@google.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191112_182543_563863_48D23612 X-CRM114-Status: GOOD ( 14.71 ) X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , linux-sh@vger.kernel.org, Catalin Marinas , Ben Segall , Guo Ren , Pavel Machek , Vincent Guittot , Paul Burton , Michael Ellerman , Geert Uytterhoeven , Mel Gorman , Jiri Slaby , Matt Turner , uclinux-h8-devel@lists.sourceforge.jp, Len Brown , linux-pm@vger.kernel.org, Heiko Carstens , linux-um@lists.infradead.org, Thomas Gleixner , Dietmar Eggemann , Richard Henderson , Greg Kroah-Hartman , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Ralf Baechle , Paul Mackerras , Andrew Morton , linux-ia64@vger.kernel.org, Tetsuo Handa , James Hogan , "James E.J. Bottomley" , Max Filippov , Vincent Chen , Ingo Molnar , linux-s390@vger.kernel.org, linux-c6x-dev@linux-c6x.org, Yoshinori Sato , linux-hexagon@vger.kernel.org, Helge Deller , linux-xtensa@linux-xtensa.org, Vasily Gorbik , Aurelien Jacquiot , linux-m68k@lists.linux-m68k.org, Stafford Horne , linux-arm-kernel@lists.infradead.org, Chris Zankel , Tony Luck , Douglas Anderson , Benjamin Herrenschmidt , Dmitry Safonov <0x7f454c46@gmail.com>, Will Deacon , Daniel Thompson , Brian Cain , Christian Borntraeger , kgdb-bugreport@lists.sourceforge.net, linux-snps-arc@lists.infradead.org, Fenghua Yu , Borislav Petkov , Jeff Dike , Ivan Kokshaysky , Greentime Hu , Guan Xuetao , linux-parisc@vger.kernel.org, linux-alpha@vger.kernel.org, Ley Foon Tan , "David S. Miller" , Rich Felker , Peter Zijlstra , "H. Peter Anvin" , sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, Anton Ivanov , Jonas Bonn , Richard Weinberger , x86@kernel.org, Russell King , clang-built-linux@googlegroups.com, Ingo Molnar , Mark Salter , Albert Ou , Stefan Kristiansson , openrisc@lists.librecores.org, Paul Walmsley , Michal Simek , Vineet Gupta , linux-mips@vger.kernel.org, Sergey Senozhatsky , Palmer Dabbelt , Jason Wessel , nios2-dev@lists.rocketboards.org, linuxppc-dev@lists.ozlabs.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+linux-snps-arc=archiver.kernel.org@lists.infradead.org On 11/13/19 1:23 AM, Sergey Senozhatsky wrote: > On (19/11/12 19:12), Sergey Senozhatsky wrote: >> On (19/11/12 09:35), Petr Mladek wrote: >> [..] >>> This is getting too complicated. It would introduce too many >>> hidden rules. While the explicitly passed loglevel parameter >>> is straightforward and clear. >> >> If loglevel is DEFAULT or NOTICE or INFO then we can overwrite it >> (either downgrade or upgrade). That's one rule, basically. Not too >> complicated, I guess. > > Can be taken even a bit further than > > show_stack(NULL, NULL, LOGLEVEL_DEBUG); > or > show_stack(NULL, NULL, LOGLEVEL_ERR); > > For instance, > > spin_lock_irqsave(&rq->lock, flags); > printk_emergency_enter(LOGLEVEL_SCHED); > ... > show_stack(...); > printk(); > printk(); > ... > spin_unlock_irqrestore(&rq->lock, flags); > > or > > spin_lock_irqsave(&uart_port->lock, flags); > printk_emergency_enter(LOGLEVEL_SCHED); > ... > printk(); > printk(); > ... Yeah, that makes sense. I believe it's up to you, Petr and Steven to decide what's better for printk(). I mean, after all you care for all this code. I guess I've pointed that in my point of view price for one-time testing code is cheaper than adding a new printk feature to swap log levels on the fly. But again, it's just how I see it - if we fix those printing problems, than in half year we will forget they ever existed, but in your proposal, there will still be some clever printk code. On the other side, also worth to note that current patches set fix problems for kdb (and for my hung task printing patch), but it's incomplete for sysrq driver. I've gone through functions used by sysrq driver and the same changes introducing log level parameter would be needed for: sched_show_task(), debug_show_all_locks(), show_regs(), show_state(), show_mem(). Some of them don't need any platform changes, but at least show_regs() needs. So, you also need to have that in mind making the decision. Thanks, Dmitry _______________________________________________ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc