| 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/smp_lock.h> |
| 12 | #include <linux/interrupt.h> |
| 13 | #include <linux/suspend.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/syscalls.h> |
| 16 | #include <linux/freezer.h> |
| 17 | |
| 18 | /* |
| 19 | * Timeout for stopping processes |
| 20 | */ |
| 21 | #define TIMEOUT (20 * HZ) |
| 22 | |
| 23 | #define FREEZER_KERNEL_THREADS 0 |
| 24 | #define FREEZER_USER_SPACE 1 |
| 25 | |
| 26 | static inline int freezeable(struct task_struct * p) |
| 27 | { |
| 28 | if ((p == current) || |
| 29 | (p->flags & PF_NOFREEZE) || |
| 30 | (p->exit_state == EXIT_ZOMBIE) || |
| 31 | (p->exit_state == EXIT_DEAD)) |
| 32 | return 0; |
| 33 | return 1; |
| 34 | } |
| 35 | |
| 36 | /* Refrigerator is place where frozen processes are stored :-). */ |
| 37 | void refrigerator(void) |
| 38 | { |
| 39 | /* Hmm, should we be allowed to suspend when there are realtime |
| 40 | processes around? */ |
| 41 | long save; |
| 42 | save = current->state; |
| 43 | pr_debug("%s entered refrigerator\n", current->comm); |
| 44 | |
| 45 | frozen_process(current); |
| 46 | spin_lock_irq(¤t->sighand->siglock); |
| 47 | recalc_sigpending(); /* We sent fake signal, clean it up */ |
| 48 | spin_unlock_irq(¤t->sighand->siglock); |
| 49 | |
| 50 | while (frozen(current)) { |
| 51 | current->state = TASK_UNINTERRUPTIBLE; |
| 52 | schedule(); |
| 53 | } |
| 54 | pr_debug("%s left refrigerator\n", current->comm); |
| 55 | current->state = save; |
| 56 | } |
| 57 | |
| 58 | static inline void freeze_process(struct task_struct *p) |
| 59 | { |
| 60 | unsigned long flags; |
| 61 | |
| 62 | if (!freezing(p)) { |
| 63 | rmb(); |
| 64 | if (!frozen(p)) { |
| 65 | if (p->state == TASK_STOPPED) |
| 66 | force_sig_specific(SIGSTOP, p); |
| 67 | |
| 68 | freeze(p); |
| 69 | spin_lock_irqsave(&p->sighand->siglock, flags); |
| 70 | signal_wake_up(p, p->state == TASK_STOPPED); |
| 71 | spin_unlock_irqrestore(&p->sighand->siglock, flags); |
| 72 | } |
| 73 | } |
| 74 | } |
| 75 | |
| 76 | static void cancel_freezing(struct task_struct *p) |
| 77 | { |
| 78 | unsigned long flags; |
| 79 | |
| 80 | if (freezing(p)) { |
| 81 | pr_debug(" clean up: %s\n", p->comm); |
| 82 | do_not_freeze(p); |
| 83 | spin_lock_irqsave(&p->sighand->siglock, flags); |
| 84 | recalc_sigpending_tsk(p); |
| 85 | spin_unlock_irqrestore(&p->sighand->siglock, flags); |
| 86 | } |
| 87 | } |
| 88 | |
| 89 | static inline int is_user_space(struct task_struct *p) |
| 90 | { |
| 91 | return p->mm && !(p->flags & PF_BORROWED_MM); |
| 92 | } |
| 93 | |
| 94 | static unsigned int try_to_freeze_tasks(int freeze_user_space) |
| 95 | { |
| 96 | struct task_struct *g, *p; |
| 97 | unsigned long end_time; |
| 98 | unsigned int todo; |
| 99 | |
| 100 | end_time = jiffies + TIMEOUT; |
| 101 | do { |
| 102 | todo = 0; |
| 103 | read_lock(&tasklist_lock); |
| 104 | do_each_thread(g, p) { |
| 105 | if (!freezeable(p)) |
| 106 | continue; |
| 107 | |
| 108 | if (frozen(p)) |
| 109 | continue; |
| 110 | |
| 111 | if (p->state == TASK_TRACED && frozen(p->parent)) { |
| 112 | cancel_freezing(p); |
| 113 | continue; |
| 114 | } |
| 115 | if (is_user_space(p)) { |
| 116 | if (!freeze_user_space) |
| 117 | continue; |
| 118 | |
| 119 | /* Freeze the task unless there is a vfork |
| 120 | * completion pending |
| 121 | */ |
| 122 | if (!p->vfork_done) |
| 123 | freeze_process(p); |
| 124 | } else { |
| 125 | if (freeze_user_space) |
| 126 | continue; |
| 127 | |
| 128 | freeze_process(p); |
| 129 | } |
| 130 | todo++; |
| 131 | } while_each_thread(g, p); |
| 132 | read_unlock(&tasklist_lock); |
| 133 | yield(); /* Yield is okay here */ |
| 134 | if (todo && time_after(jiffies, end_time)) |
| 135 | break; |
| 136 | } while (todo); |
| 137 | |
| 138 | if (todo) { |
| 139 | /* This does not unfreeze processes that are already frozen |
| 140 | * (we have slightly ugly calling convention in that respect, |
| 141 | * and caller must call thaw_processes() if something fails), |
| 142 | * but it cleans up leftover PF_FREEZE requests. |
| 143 | */ |
| 144 | printk("\n"); |
| 145 | printk(KERN_ERR "Stopping %s timed out after %d seconds " |
| 146 | "(%d tasks refusing to freeze):\n", |
| 147 | freeze_user_space ? "user space processes" : |
| 148 | "kernel threads", |
| 149 | TIMEOUT / HZ, todo); |
| 150 | read_lock(&tasklist_lock); |
| 151 | do_each_thread(g, p) { |
| 152 | if (is_user_space(p) == !freeze_user_space) |
| 153 | continue; |
| 154 | |
| 155 | if (freezeable(p) && !frozen(p)) |
| 156 | printk(KERN_ERR " %s\n", p->comm); |
| 157 | |
| 158 | cancel_freezing(p); |
| 159 | } while_each_thread(g, p); |
| 160 | read_unlock(&tasklist_lock); |
| 161 | } |
| 162 | |
| 163 | return todo; |
| 164 | } |
| 165 | |
| 166 | /** |
| 167 | * freeze_processes - tell processes to enter the refrigerator |
| 168 | * |
| 169 | * Returns 0 on success, or the number of processes that didn't freeze, |
| 170 | * although they were told to. |
| 171 | */ |
| 172 | int freeze_processes(void) |
| 173 | { |
| 174 | unsigned int nr_unfrozen; |
| 175 | |
| 176 | printk("Stopping tasks ... "); |
| 177 | nr_unfrozen = try_to_freeze_tasks(FREEZER_USER_SPACE); |
| 178 | if (nr_unfrozen) |
| 179 | return nr_unfrozen; |
| 180 | |
| 181 | sys_sync(); |
| 182 | nr_unfrozen = try_to_freeze_tasks(FREEZER_KERNEL_THREADS); |
| 183 | if (nr_unfrozen) |
| 184 | return nr_unfrozen; |
| 185 | |
| 186 | printk("done.\n"); |
| 187 | BUG_ON(in_atomic()); |
| 188 | return 0; |
| 189 | } |
| 190 | |
| 191 | static void thaw_tasks(int thaw_user_space) |
| 192 | { |
| 193 | struct task_struct *g, *p; |
| 194 | |
| 195 | read_lock(&tasklist_lock); |
| 196 | do_each_thread(g, p) { |
| 197 | if (!freezeable(p)) |
| 198 | continue; |
| 199 | |
| 200 | if (is_user_space(p) == !thaw_user_space) |
| 201 | continue; |
| 202 | |
| 203 | if (!thaw_process(p)) |
| 204 | printk(KERN_WARNING " Strange, %s not stopped\n", |
| 205 | p->comm ); |
| 206 | } while_each_thread(g, p); |
| 207 | read_unlock(&tasklist_lock); |
| 208 | } |
| 209 | |
| 210 | void thaw_processes(void) |
| 211 | { |
| 212 | printk("Restarting tasks ... "); |
| 213 | thaw_tasks(FREEZER_KERNEL_THREADS); |
| 214 | thaw_tasks(FREEZER_USER_SPACE); |
| 215 | schedule(); |
| 216 | printk("done.\n"); |
| 217 | } |
| 218 | |
| 219 | EXPORT_SYMBOL(refrigerator); |