Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 25 Dec 2001 14:59:02 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 25 Dec 2001 14:58:53 -0500 Received: from smtp1.vol.cz ([195.250.128.73]:58379 "EHLO smtp1.vol.cz") by vger.kernel.org with ESMTP id ; Tue, 25 Dec 2001 14:58:38 -0500 Date: Tue, 25 Dec 2001 11:33:56 +0000 From: Pavel Machek To: Russell King Cc: linux-kernel@vger.kernel.org Subject: Re: Total system lockup with Alt-SysRQ-L Message-ID: <20011225113355.A37@toy.ucw.cz> In-Reply-To: <20011223175846.B27993@flint.arm.linux.org.uk> <20011224083752.A1181@flint.arm.linux.org.uk> <20011224122605.A2110@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0.1i In-Reply-To: <20011224122605.A2110@flint.arm.linux.org.uk>; from rmk@arm.linux.org.uk on Mon, Dec 24, 2001 at 12:26:05PM +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > We do have some tests in the do_exit() path to panic if/when init dies, > which rely on the init PID being '1'. Unfortunately, these don't trigger > because of the following bogosity in drivers/char/sysrq.c: > > if (p->pid == 1 && even_init) > /* Ugly hack to kill init */ > p->pid = 0x8000; > > So, I propose we get rid of this "ugly hack", and the alt-sysrq-l > option altogether - it would appear to serve no useful purpose. Ask mj if it was ever usefull... But I guess it was not. Kill it. > > Here is a patch that does just this. It should apply to 2.4.17 and 2.5.1 > kernels fine (generated on 2.5.1). > > --- orig/drivers/char/sysrq.c Wed Dec 12 11:37:40 2001 > +++ linux/drivers/char/sysrq.c Mon Dec 24 12:19:58 2001 > @@ -284,24 +284,20 @@ > > /* signal sysrq helper function > * Sends a signal to all user processes */ > -static void send_sig_all(int sig, int even_init) > +static void send_sig_all(int sig) > { > struct task_struct *p; > > for_each_task(p) { > - if (p->mm) { /* Not swapper nor kernel thread */ > - if (p->pid == 1 && even_init) > - /* Ugly hack to kill init */ > - p->pid = 0x8000; > - if (p->pid != 1) > - force_sig(sig, p); > - } > + if (p->mm && p->pid != 1) > + /* Not swapper, init nor kernel thread */ > + force_sig(sig, p); > } > } > > static void sysrq_handle_term(int key, struct pt_regs *pt_regs, > struct kbd_struct *kbd, struct tty_struct *tty) { > - send_sig_all(SIGTERM, 0); > + send_sig_all(SIGTERM); > console_loglevel = 8; > } > static struct sysrq_key_op sysrq_term_op = { > @@ -312,7 +308,7 @@ > > static void sysrq_handle_kill(int key, struct pt_regs *pt_regs, > struct kbd_struct *kbd, struct tty_struct *tty) { > - send_sig_all(SIGKILL, 0); > + send_sig_all(SIGKILL); > console_loglevel = 8; > } > static struct sysrq_key_op sysrq_kill_op = { > @@ -321,17 +317,6 @@ > action_msg: "Kill All Tasks", > }; > > -static void sysrq_handle_killall(int key, struct pt_regs *pt_regs, > - struct kbd_struct *kbd, struct tty_struct *tty) { > - send_sig_all(SIGKILL, 1); > - console_loglevel = 8; > -} > -static struct sysrq_key_op sysrq_killall_op = { > - handler: sysrq_handle_killall, > - help_msg: "killalL", > - action_msg: "Kill All Tasks (even init)", > -}; > - > /* END SIGNAL SYSRQ HANDLERS BLOCK */ > > > @@ -366,7 +351,7 @@ > #else > /* k */ NULL, > #endif > -/* l */ &sysrq_killall_op, > +/* l */ NULL, > /* m */ &sysrq_showmem_op, > /* n */ NULL, > /* o */ NULL, /* This will often be registered > > -- > Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux > http://www.arm.linux.org.uk/personal/aboutme.html > > - > 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/ -- Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt, details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html. - 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/