155 lines
3.3 KiB
C
155 lines
3.3 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/interrupt.h>
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#include <linux/suspend.h>
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#include <linux/module.h>
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#include <linux/syscalls.h>
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#include <linux/freezer.h>
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/*
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* Timeout for stopping processes
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*/
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#define TIMEOUT (20 * 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 != 0))
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return 0;
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return 1;
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}
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static int try_to_freeze_tasks(bool sig_only)
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{
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struct task_struct *g, *p;
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unsigned long end_time;
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unsigned int todo;
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struct timeval start, end;
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u64 elapsed_csecs64;
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unsigned int elapsed_csecs;
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do_gettimeofday(&start);
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end_time = jiffies + TIMEOUT;
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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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if (frozen(p) || !freezeable(p))
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continue;
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if (!freeze_task(p, sig_only))
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continue;
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/*
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* Now that we've done set_freeze_flag, don't
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* perturb a task in TASK_STOPPED or TASK_TRACED.
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* It is "frozen enough". If the task does wake
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* up, it will immediately call try_to_freeze.
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*/
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if (!task_is_stopped_or_traced(p) &&
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!freezer_should_skip(p))
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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, end_time))
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break;
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} while (todo);
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do_gettimeofday(&end);
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elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
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do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
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elapsed_csecs = elapsed_csecs64;
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if (todo) {
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/* This does not unfreeze processes that are already frozen
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* (we have slightly ugly calling convention in that respect,
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* and caller must call thaw_processes() if something fails),
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* but it cleans up leftover PF_FREEZE requests.
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*/
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printk("\n");
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printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
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"(%d tasks refusing to freeze):\n",
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elapsed_csecs / 100, elapsed_csecs % 100, todo);
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show_state();
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read_lock(&tasklist_lock);
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do_each_thread(g, p) {
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task_lock(p);
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if (freezing(p) && !freezer_should_skip(p))
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printk(KERN_ERR " %s\n", p->comm);
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cancel_freezing(p);
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task_unlock(p);
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} while_each_thread(g, p);
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read_unlock(&tasklist_lock);
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} else {
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printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
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elapsed_csecs % 100);
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}
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return todo ? -EBUSY : 0;
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}
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/**
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* freeze_processes - tell processes to enter the refrigerator
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*/
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int freeze_processes(void)
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{
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int error;
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printk("Freezing user space processes ... ");
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error = try_to_freeze_tasks(true);
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if (error)
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goto Exit;
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printk("done.\n");
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printk("Freezing remaining freezable tasks ... ");
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error = try_to_freeze_tasks(false);
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if (error)
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goto Exit;
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printk("done.");
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Exit:
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BUG_ON(in_atomic());
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printk("\n");
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return error;
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}
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static void thaw_tasks(bool nosig_only)
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{
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struct task_struct *g, *p;
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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 (nosig_only && should_send_signal(p))
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continue;
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if (cgroup_frozen(p))
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continue;
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thaw_process(p);
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} while_each_thread(g, p);
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read_unlock(&tasklist_lock);
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}
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void thaw_processes(void)
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{
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printk("Restarting tasks ... ");
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thaw_tasks(true);
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thaw_tasks(false);
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schedule();
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printk("done.\n");
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}
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