linux/arch/um/kernel/reboot.c
Anton Vorontsov 137d1a26c8 um: fix possible race on task->mm
Checking for task->mm is dangerous as ->mm might disappear (exit_mm()
assigns NULL under task_lock(), so tasklist lock is not enough).

We can't use get_task_mm()/mmput() pair as mmput() might sleep, so let's
take the task lock while we care about its mm.

Note that we should also use find_lock_task_mm() to check all process'
threads for a valid mm, but for uml we'll do it in a separate patch.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-31 17:49:30 -07:00

64 lines
1008 B
C

/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include "linux/sched.h"
#include "linux/spinlock.h"
#include "linux/slab.h"
#include "kern_util.h"
#include "os.h"
#include "skas.h"
void (*pm_power_off)(void);
static void kill_off_processes(void)
{
if (proc_mm)
/*
* FIXME: need to loop over userspace_pids
*/
os_kill_ptraced_process(userspace_pid[0], 1);
else {
struct task_struct *p;
int pid;
read_lock(&tasklist_lock);
for_each_process(p) {
task_lock(p);
if (!p->mm) {
task_unlock(p);
continue;
}
pid = p->mm->context.id.u.pid;
task_unlock(p);
os_kill_ptraced_process(pid, 1);
}
read_unlock(&tasklist_lock);
}
}
void uml_cleanup(void)
{
kmalloc_ok = 0;
do_uml_exitcalls();
kill_off_processes();
}
void machine_restart(char * __unused)
{
uml_cleanup();
reboot_skas();
}
void machine_power_off(void)
{
uml_cleanup();
halt_skas();
}
void machine_halt(void)
{
machine_power_off();
}