From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753804AbYJTMOe (ORCPT ); Mon, 20 Oct 2008 08:14:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752092AbYJTMOZ (ORCPT ); Mon, 20 Oct 2008 08:14:25 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:59319 "EHLO UNKNOWN" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751916AbYJTMOY (ORCPT ); Mon, 20 Oct 2008 08:14:24 -0400 Date: Mon, 20 Oct 2008 14:14:12 +0200 From: Pavel Machek To: Bodo Eggert <7eggert@gmx.de> Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] softpanic - halt booting, but allow reading why Message-ID: <20081020121412.GA10214@ucw.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2008-10-16 13:58:12, Bodo Eggert wrote: > While booting, certain panic()s have the purpose of just stopping the > machnine. This has the unfortunate side effect of preventing the user > from scrolling and looking at the cause. > > This patch adds a softpanic() function, which behaves similar to panic() > in stopping the boot and possibly rebooting after a timeout, but it > does allow background activity. > > Signed-off-by: Bodo Eggert <7eggert@gmx.de> ACK. Can you send it to akpm so that it gets queued? Pavel > --- > > I thought about merging both functions, but I don't think it would work out. > > diff -pruNXdontdiff linux-2.6.27/include/linux/kernel.h linux-2.6.27.softpanic/include/linux/kernel.h > --- linux-2.6.27/include/linux/kernel.h 2008-10-10 13:18:43.000000000 +0200 > +++ linux-2.6.27.softpanic/include/linux/kernel.h 2008-10-10 19:23:43.000000000 +0200 > @@ -144,6 +144,12 @@ extern struct atomic_notifier_head panic > extern long (*panic_blink)(long time); > NORET_TYPE void panic(const char * fmt, ...) > __attribute__ ((NORET_AND format (printf, 1, 2))) __cold; > +#ifdef CONFIG_SOFTPANIC > +NORET_TYPE void softpanic(const char * fmt, ...) > + __attribute__ ((NORET_AND format (printf, 1, 2))) __cold; > +#else > +# define softpanic(...) do { panic(__VA_ARGS__); } while (0) > +#endif > extern void oops_enter(void); > extern void oops_exit(void); > extern int oops_may_print(void); > diff -pruNXdontdiff linux-2.6.27/init/Kconfig linux-2.6.27.softpanic/init/Kconfig > --- linux-2.6.27/init/Kconfig 2008-10-10 13:18:44.000000000 +0200 > +++ linux-2.6.27.softpanic/init/Kconfig 2008-10-10 18:32:03.000000000 +0200 > @@ -618,6 +618,14 @@ config BUG > option for embedded systems with no facilities for reporting errors. > Just say Y. > > +config SOFTPANIC > + bool "Enable softpanic for boot errors" if EMBEDDED > + default y > + help > + Enabling this option changes a hard panic on boot errors to a > + soft panic, which does not stop the system completely. > + You can still scroll the screen and read the messages. > + > config ELF_CORE > default y > bool "Enable ELF core dumps" if EMBEDDED > diff -pruNXdontdiff linux-2.6.27/init/do_mounts.c linux-2.6.27.softpanic/init/do_mounts.c > --- linux-2.6.27/init/do_mounts.c 2008-10-10 13:18:44.000000000 +0200 > +++ linux-2.6.27.softpanic/init/do_mounts.c 2008-10-10 18:32:03.000000000 +0200 > @@ -263,7 +263,7 @@ retry: > printk("Please append a correct \"root=\" boot option; here are the available partitions:\n"); > > printk_all_partitions(); > - panic("VFS: Unable to mount root fs on %s", b); > + softpanic("VFS: Unable to mount root fs on %s", b); > } > > printk("List of all partitions:\n"); > @@ -275,7 +275,7 @@ retry: > #ifdef CONFIG_BLOCK > __bdevname(ROOT_DEV, b); > #endif > - panic("VFS: Unable to mount root fs on %s", b); > + softpanic("VFS: Unable to mount root fs on %s", b); > out: > putname(fs_names); > } > diff -pruNXdontdiff linux-2.6.27/init/main.c linux-2.6.27.softpanic/init/main.c > --- linux-2.6.27/init/main.c 2008-10-10 13:18:44.000000000 +0200 > +++ linux-2.6.27.softpanic/init/main.c 2008-10-10 18:32:03.000000000 +0200 > @@ -621,7 +621,7 @@ asmlinkage void __init start_kernel(void > */ > console_init(); > if (panic_later) > - panic(panic_later, panic_param); > + softpanic(panic_later, panic_param); > > lockdep_info(); > > @@ -830,7 +830,7 @@ static int noinline init_post(void) > run_init_process("/bin/init"); > run_init_process("/bin/sh"); > > - panic("No init found. Try passing init= option to kernel."); > + softpanic("No init found. Try passing init= option to kernel."); > } > > static int __init kernel_init(void * unused) > diff -pruNXdontdiff linux-2.6.27/kernel/panic.c linux-2.6.27.softpanic/kernel/panic.c > --- linux-2.6.27/kernel/panic.c 2008-10-10 13:18:45.000000000 +0200 > +++ linux-2.6.27.softpanic/kernel/panic.c 2008-10-10 20:13:37.000000000 +0200 > @@ -140,9 +140,68 @@ NORET_TYPE void panic(const char * fmt, > i++; > } > } > - > EXPORT_SYMBOL(panic); > > +#ifdef CONFIG_SOFTPANIC > +NORET_TYPE void softpanic(const char * fmt, ...) > +{ > + long i; > + static char buf[1024]; > + va_list args; > +#if defined(CONFIG_S390) > + unsigned long caller = (unsigned long) __builtin_return_address(0); > +#endif > + > + va_start(args, fmt); > + vsnprintf(buf, sizeof(buf), fmt, args); > + va_end(args); > + printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); > + > + atomic_notifier_call_chain(&panic_notifier_list, 0, buf); > + > + if (!panic_blink) > + panic_blink = no_blink; > + > + if (panic_timeout > 0) { > + /* > + * Delay timeout seconds before rebooting the machine. > + * We can't use the "normal" timers since we just panicked.. > + */ > + printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout); > + for (i = 0; i < panic_timeout*1000; ) { > + touch_nmi_watchdog(); > + i += panic_blink(i); > + mdelay(1); > + i++; > + } > + /* This will not be a clean reboot, with everything > + * shutting down. But if there is a chance of > + * rebooting the system it will be rebooted. > + */ > + kernel_restart(NULL); > + } > +#ifdef __sparc__ > + { > + extern int stop_a_enabled; > + /* Make sure the user can actually press Stop-A (L1-A) */ > + stop_a_enabled = 1; > + printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); > + } > +#endif > +#if defined(CONFIG_S390) > + disabled_wait(caller); > +#endif > + for (i = 0;;) { > + touch_softlockup_watchdog(); > + i += panic_blink(i); > + msleep(1); > + i++; > + } > +} > +EXPORT_SYMBOL(softpanic); > +#endif > + > + > /** > * print_tainted - return a string to represent the kernel taint state. > * > -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html