Root/
| 1 | /* |
| 2 | * drivers/power/process.c - Functions for starting/stopping processes on |
| 3 | * suspend transitions. |
| 4 | * |
| 5 | * Originally from swsusp. |
| 6 | */ |
| 7 | |
| 8 | |
| 9 | #undef DEBUG |
| 10 | |
| 11 | #include <linux/interrupt.h> |
| 12 | #include <linux/oom.h> |
| 13 | #include <linux/suspend.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/syscalls.h> |
| 16 | #include <linux/freezer.h> |
| 17 | #include <linux/delay.h> |
| 18 | #include <linux/workqueue.h> |
| 19 | |
| 20 | /* |
| 21 | * Timeout for stopping processes |
| 22 | */ |
| 23 | #define TIMEOUT (20 * HZ) |
| 24 | |
| 25 | static inline int freezable(struct task_struct * p) |
| 26 | { |
| 27 | if ((p == current) || |
| 28 | (p->flags & PF_NOFREEZE) || |
| 29 | (p->exit_state != 0)) |
| 30 | return 0; |
| 31 | return 1; |
| 32 | } |
| 33 | |
| 34 | static int try_to_freeze_tasks(bool sig_only) |
| 35 | { |
| 36 | struct task_struct *g, *p; |
| 37 | unsigned long end_time; |
| 38 | unsigned int todo; |
| 39 | bool wq_busy = false; |
| 40 | struct timeval start, end; |
| 41 | u64 elapsed_csecs64; |
| 42 | unsigned int elapsed_csecs; |
| 43 | bool wakeup = false; |
| 44 | |
| 45 | do_gettimeofday(&start); |
| 46 | |
| 47 | end_time = jiffies + TIMEOUT; |
| 48 | |
| 49 | if (!sig_only) |
| 50 | freeze_workqueues_begin(); |
| 51 | |
| 52 | while (true) { |
| 53 | todo = 0; |
| 54 | read_lock(&tasklist_lock); |
| 55 | do_each_thread(g, p) { |
| 56 | if (frozen(p) || !freezable(p)) |
| 57 | continue; |
| 58 | |
| 59 | if (!freeze_task(p, sig_only)) |
| 60 | continue; |
| 61 | |
| 62 | /* |
| 63 | * Now that we've done set_freeze_flag, don't |
| 64 | * perturb a task in TASK_STOPPED or TASK_TRACED. |
| 65 | * It is "frozen enough". If the task does wake |
| 66 | * up, it will immediately call try_to_freeze. |
| 67 | * |
| 68 | * Because freeze_task() goes through p's |
| 69 | * scheduler lock after setting TIF_FREEZE, it's |
| 70 | * guaranteed that either we see TASK_RUNNING or |
| 71 | * try_to_stop() after schedule() in ptrace/signal |
| 72 | * stop sees TIF_FREEZE. |
| 73 | */ |
| 74 | if (!task_is_stopped_or_traced(p) && |
| 75 | !freezer_should_skip(p)) |
| 76 | todo++; |
| 77 | } while_each_thread(g, p); |
| 78 | read_unlock(&tasklist_lock); |
| 79 | |
| 80 | if (!sig_only) { |
| 81 | wq_busy = freeze_workqueues_busy(); |
| 82 | todo += wq_busy; |
| 83 | } |
| 84 | |
| 85 | if (!todo || time_after(jiffies, end_time)) |
| 86 | break; |
| 87 | |
| 88 | if (pm_wakeup_pending()) { |
| 89 | wakeup = true; |
| 90 | break; |
| 91 | } |
| 92 | |
| 93 | /* |
| 94 | * We need to retry, but first give the freezing tasks some |
| 95 | * time to enter the regrigerator. |
| 96 | */ |
| 97 | msleep(10); |
| 98 | } |
| 99 | |
| 100 | do_gettimeofday(&end); |
| 101 | elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); |
| 102 | do_div(elapsed_csecs64, NSEC_PER_SEC / 100); |
| 103 | elapsed_csecs = elapsed_csecs64; |
| 104 | |
| 105 | if (todo) { |
| 106 | /* This does not unfreeze processes that are already frozen |
| 107 | * (we have slightly ugly calling convention in that respect, |
| 108 | * and caller must call thaw_processes() if something fails), |
| 109 | * but it cleans up leftover PF_FREEZE requests. |
| 110 | */ |
| 111 | printk("\n"); |
| 112 | printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds " |
| 113 | "(%d tasks refusing to freeze, wq_busy=%d):\n", |
| 114 | wakeup ? "aborted" : "failed", |
| 115 | elapsed_csecs / 100, elapsed_csecs % 100, |
| 116 | todo - wq_busy, wq_busy); |
| 117 | |
| 118 | thaw_workqueues(); |
| 119 | |
| 120 | read_lock(&tasklist_lock); |
| 121 | do_each_thread(g, p) { |
| 122 | task_lock(p); |
| 123 | if (!wakeup && freezing(p) && !freezer_should_skip(p)) |
| 124 | sched_show_task(p); |
| 125 | cancel_freezing(p); |
| 126 | task_unlock(p); |
| 127 | } while_each_thread(g, p); |
| 128 | read_unlock(&tasklist_lock); |
| 129 | } else { |
| 130 | printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100, |
| 131 | elapsed_csecs % 100); |
| 132 | } |
| 133 | |
| 134 | return todo ? -EBUSY : 0; |
| 135 | } |
| 136 | |
| 137 | /** |
| 138 | * freeze_processes - tell processes to enter the refrigerator |
| 139 | */ |
| 140 | int freeze_processes(void) |
| 141 | { |
| 142 | int error; |
| 143 | |
| 144 | printk("Freezing user space processes ... "); |
| 145 | error = try_to_freeze_tasks(true); |
| 146 | if (error) |
| 147 | goto Exit; |
| 148 | printk("done.\n"); |
| 149 | |
| 150 | printk("Freezing remaining freezable tasks ... "); |
| 151 | error = try_to_freeze_tasks(false); |
| 152 | if (error) |
| 153 | goto Exit; |
| 154 | printk("done."); |
| 155 | |
| 156 | oom_killer_disable(); |
| 157 | Exit: |
| 158 | BUG_ON(in_atomic()); |
| 159 | printk("\n"); |
| 160 | |
| 161 | return error; |
| 162 | } |
| 163 | |
| 164 | static void thaw_tasks(bool nosig_only) |
| 165 | { |
| 166 | struct task_struct *g, *p; |
| 167 | |
| 168 | read_lock(&tasklist_lock); |
| 169 | do_each_thread(g, p) { |
| 170 | if (!freezable(p)) |
| 171 | continue; |
| 172 | |
| 173 | if (nosig_only && should_send_signal(p)) |
| 174 | continue; |
| 175 | |
| 176 | if (cgroup_freezing_or_frozen(p)) |
| 177 | continue; |
| 178 | |
| 179 | thaw_process(p); |
| 180 | } while_each_thread(g, p); |
| 181 | read_unlock(&tasklist_lock); |
| 182 | } |
| 183 | |
| 184 | void thaw_processes(void) |
| 185 | { |
| 186 | oom_killer_enable(); |
| 187 | |
| 188 | printk("Restarting tasks ... "); |
| 189 | thaw_workqueues(); |
| 190 | thaw_tasks(true); |
| 191 | thaw_tasks(false); |
| 192 | schedule(); |
| 193 | printk("done.\n"); |
| 194 | } |
| 195 | |
| 196 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
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v3.9
