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