Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753200AbZGTMpU (ORCPT ); Mon, 20 Jul 2009 08:45:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750779AbZGTMpT (ORCPT ); Mon, 20 Jul 2009 08:45:19 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:64451 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751800AbZGTMpS (ORCPT ); Mon, 20 Jul 2009 08:45:18 -0400 Message-ID: <4A64672E.8020005@cn.fujitsu.com> Date: Mon, 20 Jul 2009 20:46:38 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Andrew Morton , Neil Horman , Vivek Goyal , Brayan Arraes , "Eric W. Biederman" , LKML Subject: [PATCH] sysrq, kdump: fix regression, revert "simplify sysrq-c handler" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2814 Lines: 79 1) This fix breaks our tools. This fix changes the ABI. panic_on_oops is default 0, and a lots system do not specify the boot option "panic", thus, Sysrq-c will not cause CrashDump(Kdump) as expected. 2) When CONFIG_KEXEC=n, Sysrq-c should become an invalid command like Sysrq-D(CONFIG_LOCKDEP, show-all-locks). But this fix makes it a valid command and let it do a hazard thing: cause a page fault(NULL dereference) in kernel. So, we revert this fix. |commit d6580a9f15238b87e618310c862231ae3f352d2d |Author: Neil Horman |Date: Wed Jun 17 16:28:17 2009 -0700 | kexec: sysrq: simplify sysrq-c handler | Currently the sysrq-c handler is bit over-engineered. Its behavior is | dependent on a few compile time and run time factors that alter its | behavior which is really unnecessecary. | If CONFIG_KEXEC is not configured, sysrq-c, crashes the system with a NULL | pointer dereference. If CONFIG_KEXEC is configured, it calls crash_kexec | directly, which implies that the kexec kernel will either be booted (if | its been previously loaded), or it will simply do nothing (the no kexec | kernel has been loaded). | It would be much easier to just simplify the whole thing to dereference a | NULL pointer all the time regardless of configuration. That way, it will | always try to crash the system, and if a kexec kernel has been loaded into | reserved space, it will still boot from the page fault trap handler | (assuming panic_on_oops is set appropriately). Signed-off-by: Lai Jiangshan --- diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c index 0db3585..39a05b5 100644 --- a/drivers/char/sysrq.c +++ b/drivers/char/sysrq.c @@ -121,17 +121,20 @@ static struct sysrq_key_op sysrq_unraw_op = { #define sysrq_unraw_op (*(struct sysrq_key_op *)0) #endif /* CONFIG_VT */ -static void sysrq_handle_crash(int key, struct tty_struct *tty) +#ifdef CONFIG_KEXEC +static void sysrq_handle_crashdump(int key, struct tty_struct *tty) { - char *killer = NULL; - *killer = 1; + crash_kexec(get_irq_regs()); } static struct sysrq_key_op sysrq_crashdump_op = { - .handler = sysrq_handle_crash, - .help_msg = "Crash", - .action_msg = "Trigger a crash", + .handler = sysrq_handle_crashdump, + .help_msg = "Crashdump", + .action_msg = "Trigger a crashdump", .enable_mask = SYSRQ_ENABLE_DUMP, }; +#else +#define sysrq_crashdump_op (*(struct sysrq_key_op *)0) +#endif static void sysrq_handle_reboot(int key, struct tty_struct *tty) { -- 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/