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[86.9.19.6]) by smtp.gmail.com with ESMTPSA id x17sm4434916wmi.28.2020.03.17.09.00.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2020 09:00:50 -0700 (PDT) Date: Tue, 17 Mar 2020 16:00:49 +0000 From: Daniel Thompson To: Dmitry Safonov Cc: linux-kernel@vger.kernel.org, Dmitry Safonov <0x7f454c46@gmail.com>, Andrew Morton , Greg Kroah-Hartman , Ingo Molnar , Jiri Slaby , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Tetsuo Handa , Douglas Anderson , Jason Wessel , kgdb-bugreport@lists.sourceforge.net Subject: Re: [PATCHv2 47/50] kdb: Don't play with console_loglevel Message-ID: <20200317160049.b2t52oaqifhmcv23@holly.lan> References: <20200316143916.195608-1-dima@arista.com> <20200316143916.195608-48-dima@arista.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200316143916.195608-48-dima@arista.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 16, 2020 at 02:39:13PM +0000, Dmitry Safonov wrote: > Print the stack trace with KERN_EMERG - it should be always visible. > > Playing with console_loglevel is a bad idea as there may be more > messages printed than wanted. Also the stack trace might be not printed > at all if printk() was deferred and console_loglevel was raised back > before the trace got flushed. > > Unfortunately, after rebasing on commit 2277b492582d ("kdb: Fix stack > crawling on 'running' CPUs that aren't the master"), kdb_show_stack() > uses now kdb_dump_stack_on_cpu(), which for now won't be converted as it > uses dump_stack() instead of show_stack(). > > Convert for now the branch that uses show_stack() and remove > console_loglevel exercise from that case. > > Cc: Daniel Thompson > Cc: Douglas Anderson > Cc: Jason Wessel > Cc: kgdb-bugreport@lists.sourceforge.net > Signed-off-by: Dmitry Safonov Acked-by: Daniel Thompson > --- > kernel/debug/kdb/kdb_bt.c | 15 ++++++++------- > 1 file changed, 8 insertions(+), 7 deletions(-) > > diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c > index 3de0cc780c16..43f5dcd2b9ac 100644 > --- a/kernel/debug/kdb/kdb_bt.c > +++ b/kernel/debug/kdb/kdb_bt.c > @@ -21,17 +21,18 @@ > > static void kdb_show_stack(struct task_struct *p, void *addr) > { > - int old_lvl = console_loglevel; > - > - console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; > kdb_trap_printk++; > > - if (!addr && kdb_task_has_cpu(p)) > + if (!addr && kdb_task_has_cpu(p)) { > + int old_lvl = console_loglevel; > + > + console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; > kdb_dump_stack_on_cpu(kdb_process_cpu(p)); > - else > - show_stack(p, addr); > + console_loglevel = old_lvl; > + } else { > + show_stack_loglvl(p, addr, KERN_EMERG); > + } > > - console_loglevel = old_lvl; > kdb_trap_printk--; > } > > -- > 2.25.1 >