Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757960Ab1EZRMY (ORCPT ); Thu, 26 May 2011 13:12:24 -0400 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:56101 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757659Ab1EZRMW (ORCPT ); Thu, 26 May 2011 13:12:22 -0400 Date: Thu, 26 May 2011 22:42:09 +0530 From: "K.Prasad" To: Linux Kernel Mailing List Cc: Andi Kleen , "Luck, Tony" , Vivek Goyal , kexec@lists.infradead.org, "Eric W. Biederman" , anderson@redhat.com Subject: [Patch 1/6] XPANIC: Add extended panic interface Message-ID: <20110526171209.GA17988@in.ibm.com> Reply-To: prasad@linux.vnet.ibm.com References: <20110526170722.GB23266@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110526170722.GB23266@in.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5088 Lines: 161 commit e668fa1aea7844ac4c7ea09030a2f3e647a4adb1 Author: Andi Kleen Date: Fri Nov 19 18:36:44 2010 +0100 XPANIC: Add extended panic interface One panic size doesn't fit all. Machine check has some special requirements on panic, like: - It wants to do a reboot timeout by default so that the machine check event can be logged to disk after warm reboot. - For memory errors it usually doesn't want to do crash dumps because that can lead to crash loops (dumping corrupted memory would lead to another machine check) - It doesn't want to do backtraces because machine checks are not a kernel bug. In a earlier patch this was done with various adhoc hacks, but it's cleaner to extend panic to a 'xpanic' that directly gets a flag and timeout argument. The only user right now will be x86 machine checks, but I consider it likely that other users will switch to this too. For example one obvious candidate would be the "no root found" panic which doesn't really deserve a backtrace. I exported a vpanic() interface too as a global. That's not needed by the current user, but the interface has to exist internally anyways and I could see how other code would find a v* variant of panic useful. Originally based on a suggestion by H. Peter Anvin. Signed-off-by: Andi Kleen --- include/linux/kernel.h | 11 +++++++++++ kernel/panic.c | 41 +++++++++++++++++++++++++++++++---------- 2 files changed, 42 insertions(+), 10 deletions(-) Index: linux-2.6.slim_kdump/include/linux/kernel.h =================================================================== --- linux-2.6.slim_kdump.orig/include/linux/kernel.h +++ linux-2.6.slim_kdump/include/linux/kernel.h @@ -175,10 +175,21 @@ static inline void might_fault(void) } #endif +enum panic_flags { + PANIC_NO_KEXEC = (1 << 0), + PANIC_NO_BACKTRACE = (1 << 1), +}; + extern struct atomic_notifier_head panic_notifier_list; extern long (*panic_blink)(int state); NORET_TYPE void panic(const char * fmt, ...) __attribute__ ((NORET_AND format (printf, 1, 2))) __cold; +NORET_TYPE void xpanic(enum panic_flags flags, int timeout, + const char *fmt, ...) + __attribute__ ((NORET_AND format (printf, 3, 4))) __cold; +NORET_TYPE void vpanic(enum panic_flags flags, int timeout, + const char *fmt, + va_list ap) __noreturn __cold; extern void oops_enter(void); extern void oops_exit(void); void print_oops_end_marker(void); Index: linux-2.6.slim_kdump/kernel/panic.c =================================================================== --- linux-2.6.slim_kdump.orig/kernel/panic.c +++ linux-2.6.slim_kdump/kernel/panic.c @@ -57,14 +57,37 @@ EXPORT_SYMBOL(panic_blink); * * This function never returns. */ -NORET_TYPE void panic(const char * fmt, ...) +NORET_TYPE void panic(const char *fmt, ...) +{ + va_list ap; + va_start(ap, fmt); + vpanic(0, 0, fmt, ap); +} +EXPORT_SYMBOL(panic); + +NORET_TYPE void xpanic(enum panic_flags flags, int timeout, + const char *fmt, ...) +{ + va_list ap; + va_start(ap, fmt); + xpanic(flags, timeout, fmt, ap); +} +EXPORT_SYMBOL(xpanic); + +NORET_TYPE void vpanic(enum panic_flags flags, int timeout, + const char * fmt, va_list args) { static char buf[1024]; - va_list args; long i, i_next = 0; int state = 0; /* + * Let user always override panic_timeout. + */ + if (panic_timeout > 0) + timeout = panic_timeout; + + /* * It's possible to come here directly from a panic-assertion and * not have preempt disabled. Some functions called from here want * preempt to be disabled. No point enabling it later though... @@ -73,12 +96,11 @@ NORET_TYPE void panic(const char * fmt, console_verbose(); bust_spinlocks(1); - va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); - va_end(args); printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); #ifdef CONFIG_DEBUG_BUGVERBOSE - dump_stack(); + if (!(flags & PANIC_NO_BACKTRACE)) + dump_stack(); #endif /* @@ -86,7 +108,8 @@ NORET_TYPE void panic(const char * fmt, * everything else. * Do we want to call this before we try to display a message? */ - crash_kexec(NULL); + if (!(flags & PANIC_NO_KEXEC)) + crash_kexec(NULL); kmsg_dump(KMSG_DUMP_PANIC); @@ -104,7 +127,7 @@ NORET_TYPE void panic(const char * fmt, if (!panic_blink) panic_blink = no_blink; - if (panic_timeout > 0) { + if (timeout > 0) { /* * Delay timeout seconds before rebooting the machine. * We can't use the "normal" timers since we just panicked. @@ -152,9 +175,7 @@ NORET_TYPE void panic(const char * fmt, mdelay(PANIC_TIMER_STEP); } } - -EXPORT_SYMBOL(panic); - +EXPORT_SYMBOL(vpanic); struct tnt { u8 bit; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/