mirror of
https://github.com/torvalds/linux
synced 2024-09-29 16:00:27 +00:00
3e1d1d28d9
1. Establish a simple API for process freezing defined in linux/include/sched.h: frozen(process) Check for frozen process freezing(process) Check if a process is being frozen freeze(process) Tell a process to freeze (go to refrigerator) thaw_process(process) Restart process frozen_process(process) Process is frozen now 2. Remove all references to PF_FREEZE and PF_FROZEN from all kernel sources except sched.h 3. Fix numerous locations where try_to_freeze is manually done by a driver 4. Remove the argument that is no longer necessary from two function calls. 5. Some whitespace cleanup 6. Clear potential race in refrigerator (provides an open window of PF_FREEZE cleared before setting PF_FROZEN, recalc_sigpending does not check PF_FROZEN). This patch does not address the problem of freeze_processes() violating the rule that a task may only modify its own flags by setting PF_FREEZE. This is not clean in an SMP environment. freeze(process) is therefore not SMP safe! Signed-off-by: Christoph Lameter <christoph@lameter.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
116 lines
2.5 KiB
C
116 lines
2.5 KiB
C
/*
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* drivers/power/process.c - Functions for starting/stopping processes on
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* suspend transitions.
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*
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* Originally from swsusp.
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*/
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#undef DEBUG
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#include <linux/smp_lock.h>
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#include <linux/interrupt.h>
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#include <linux/suspend.h>
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#include <linux/module.h>
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/*
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* Timeout for stopping processes
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*/
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#define TIMEOUT (6 * HZ)
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static inline int freezeable(struct task_struct * p)
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{
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if ((p == current) ||
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(p->flags & PF_NOFREEZE) ||
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(p->exit_state == EXIT_ZOMBIE) ||
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(p->exit_state == EXIT_DEAD) ||
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(p->state == TASK_STOPPED) ||
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(p->state == TASK_TRACED))
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return 0;
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return 1;
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}
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/* Refrigerator is place where frozen processes are stored :-). */
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void refrigerator(void)
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{
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/* Hmm, should we be allowed to suspend when there are realtime
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processes around? */
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long save;
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save = current->state;
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current->state = TASK_UNINTERRUPTIBLE;
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pr_debug("%s entered refrigerator\n", current->comm);
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printk("=");
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frozen_process(current);
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spin_lock_irq(¤t->sighand->siglock);
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recalc_sigpending(); /* We sent fake signal, clean it up */
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spin_unlock_irq(¤t->sighand->siglock);
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while (frozen(current))
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schedule();
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pr_debug("%s left refrigerator\n", current->comm);
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current->state = save;
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}
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/* 0 = success, else # of processes that we failed to stop */
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int freeze_processes(void)
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{
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int todo;
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unsigned long start_time;
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struct task_struct *g, *p;
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printk( "Stopping tasks: " );
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start_time = jiffies;
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do {
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todo = 0;
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read_lock(&tasklist_lock);
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do_each_thread(g, p) {
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unsigned long flags;
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if (!freezeable(p))
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continue;
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if ((frozen(p)) ||
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(p->state == TASK_TRACED) ||
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(p->state == TASK_STOPPED))
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continue;
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freeze(p);
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spin_lock_irqsave(&p->sighand->siglock, flags);
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signal_wake_up(p, 0);
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spin_unlock_irqrestore(&p->sighand->siglock, flags);
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todo++;
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} while_each_thread(g, p);
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read_unlock(&tasklist_lock);
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yield(); /* Yield is okay here */
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if (time_after(jiffies, start_time + TIMEOUT)) {
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printk( "\n" );
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printk(KERN_ERR " stopping tasks failed (%d tasks remaining)\n", todo );
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return todo;
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}
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} while(todo);
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printk( "|\n" );
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BUG_ON(in_atomic());
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return 0;
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}
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void thaw_processes(void)
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{
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struct task_struct *g, *p;
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printk( "Restarting tasks..." );
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read_lock(&tasklist_lock);
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do_each_thread(g, p) {
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if (!freezeable(p))
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continue;
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if (!thaw_process(p))
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printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
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} while_each_thread(g, p);
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read_unlock(&tasklist_lock);
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schedule();
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printk( " done\n" );
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}
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EXPORT_SYMBOL(refrigerator);
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