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6e3fbee5f1
So why are we calling smp_send_stop from machine_halt? We don't. Looking more closely at the bug report the problem here is that halt -p is called which triggers not a halt but an attempt to power off. machine_power_off calls machine_shutdown which calls smp_send_stop. If pm_power_off is set we should never make it out machine_power_off to the call of do_exit. So pm_power_off must not be set in this case. When pm_power_off is not set we expect machine_power_off to devolve into machine_halt. So how do we fix this? Playing too much with smp_send_stop is dangerous because it must also be safe to be called from panic. It looks like the obviously correct fix is to only call machine_shutdown when pm_power_off is defined. Doing that will make Andi's assumption about not scheduling true and generally simplify what must be supported. This turns machine_power_off into a noop like machine_halt when pm_power_off is not defined. If the expected behavior is that sys_reboot(LINUX_REBOOT_CMD_POWER_OFF) becomes sys_reboot(LINUX_REBOOT_CMD_HALT) if pm_power_off is NULL this is not quite a comprehensive fix as we pass a different parameter to the reboot notifier and we set system_state to a different value before calling device_shutdown(). Unfortunately any fix more comprehensive I can think of is not obviously correct. The core problem is that there is no architecture independent way to detect if machine_power will become a noop, without calling it. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
166 lines
2.9 KiB
C
166 lines
2.9 KiB
C
/* Various gunk just to reboot the machine. */
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#include <linux/module.h>
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#include <linux/reboot.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/kernel.h>
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#include <linux/ctype.h>
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#include <linux/string.h>
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#include <linux/pm.h>
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#include <asm/io.h>
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#include <asm/kdebug.h>
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#include <asm/delay.h>
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#include <asm/hw_irq.h>
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#include <asm/system.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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#include <asm/apic.h>
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/*
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* Power off function, if any
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*/
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void (*pm_power_off)(void);
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static long no_idt[3];
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static enum {
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BOOT_TRIPLE = 't',
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BOOT_KBD = 'k'
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} reboot_type = BOOT_KBD;
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static int reboot_mode = 0;
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int reboot_force;
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/* reboot=t[riple] | k[bd] [, [w]arm | [c]old]
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warm Don't set the cold reboot flag
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cold Set the cold reboot flag
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triple Force a triple fault (init)
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kbd Use the keyboard controller. cold reset (default)
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force Avoid anything that could hang.
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*/
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static int __init reboot_setup(char *str)
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{
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for (;;) {
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switch (*str) {
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case 'w':
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reboot_mode = 0x1234;
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break;
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case 'c':
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reboot_mode = 0;
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break;
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case 't':
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case 'b':
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case 'k':
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reboot_type = *str;
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break;
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case 'f':
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reboot_force = 1;
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break;
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}
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if((str = strchr(str,',')) != NULL)
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str++;
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else
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break;
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}
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return 1;
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}
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__setup("reboot=", reboot_setup);
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static inline void kb_wait(void)
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{
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int i;
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for (i=0; i<0x10000; i++)
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if ((inb_p(0x64) & 0x02) == 0)
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break;
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}
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void machine_shutdown(void)
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{
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unsigned long flags;
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/* Stop the cpus and apics */
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#ifdef CONFIG_SMP
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int reboot_cpu_id;
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/* The boot cpu is always logical cpu 0 */
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reboot_cpu_id = 0;
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/* Make certain the cpu I'm about to reboot on is online */
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if (!cpu_isset(reboot_cpu_id, cpu_online_map)) {
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reboot_cpu_id = smp_processor_id();
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}
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/* Make certain I only run on the appropriate processor */
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set_cpus_allowed(current, cpumask_of_cpu(reboot_cpu_id));
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/* O.K Now that I'm on the appropriate processor,
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* stop all of the others.
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*/
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smp_send_stop();
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#endif
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local_irq_save(flags);
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#ifndef CONFIG_SMP
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disable_local_APIC();
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#endif
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disable_IO_APIC();
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local_irq_restore(flags);
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}
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void machine_emergency_restart(void)
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{
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int i;
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/* Tell the BIOS if we want cold or warm reboot */
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*((unsigned short *)__va(0x472)) = reboot_mode;
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for (;;) {
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/* Could also try the reset bit in the Hammer NB */
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switch (reboot_type) {
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case BOOT_KBD:
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for (i=0; i<10; i++) {
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kb_wait();
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udelay(50);
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outb(0xfe,0x64); /* pulse reset low */
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udelay(50);
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}
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case BOOT_TRIPLE:
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__asm__ __volatile__("lidt (%0)": :"r" (&no_idt));
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__asm__ __volatile__("int3");
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reboot_type = BOOT_KBD;
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break;
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}
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}
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}
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void machine_restart(char * __unused)
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{
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printk("machine restart\n");
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if (!reboot_force) {
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machine_shutdown();
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}
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machine_emergency_restart();
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}
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void machine_halt(void)
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{
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}
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void machine_power_off(void)
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{
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if (pm_power_off) {
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if (!reboot_force) {
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machine_shutdown();
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}
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pm_power_off();
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}
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}
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