1 /* Freezer declarations */ 2 3 #ifndef FREEZER_H_INCLUDED 4 #define FREEZER_H_INCLUDED 5 6 #include <linux/sched.h> 7 #include <linux/wait.h> 8 9 #ifdef CONFIG_FREEZER 10 /* 11 * Check if a process has been frozen 12 */ 13 static inline int frozen(struct task_struct *p) 14 { 15 return p->flags & PF_FROZEN; 16 } 17 18 /* 19 * Check if there is a request to freeze a process 20 */ 21 static inline int freezing(struct task_struct *p) 22 { 23 return test_tsk_thread_flag(p, TIF_FREEZE); 24 } 25 26 /* 27 * Request that a process be frozen 28 */ 29 static inline void set_freeze_flag(struct task_struct *p) 30 { 31 set_tsk_thread_flag(p, TIF_FREEZE); 32 } 33 34 /* 35 * Sometimes we may need to cancel the previous 'freeze' request 36 */ 37 static inline void clear_freeze_flag(struct task_struct *p) 38 { 39 clear_tsk_thread_flag(p, TIF_FREEZE); 40 } 41 42 static inline bool should_send_signal(struct task_struct *p) 43 { 44 return !(p->flags & PF_FREEZER_NOSIG); 45 } 46 47 /* Takes and releases task alloc lock using task_lock() */ 48 extern int thaw_process(struct task_struct *p); 49 50 extern void refrigerator(void); 51 extern int freeze_processes(void); 52 extern void thaw_processes(void); 53 54 static inline int try_to_freeze(void) 55 { 56 if (freezing(current)) { 57 refrigerator(); 58 return 1; 59 } else 60 return 0; 61 } 62 63 extern bool freeze_task(struct task_struct *p, bool sig_only); 64 extern void cancel_freezing(struct task_struct *p); 65 66 #ifdef CONFIG_CGROUP_FREEZER 67 extern int cgroup_frozen(struct task_struct *task); 68 #else /* !CONFIG_CGROUP_FREEZER */ 69 static inline int cgroup_frozen(struct task_struct *task) { return 0; } 70 #endif /* !CONFIG_CGROUP_FREEZER */ 71 72 /* 73 * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it 74 * calls wait_for_completion(&vfork) and reset right after it returns from this 75 * function. Next, the parent should call try_to_freeze() to freeze itself 76 * appropriately in case the child has exited before the freezing of tasks is 77 * complete. However, we don't want kernel threads to be frozen in unexpected 78 * places, so we allow them to block freeze_processes() instead or to set 79 * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork 80 * parents. Fortunately, in the ____call_usermodehelper() case the parent won't 81 * really block freeze_processes(), since ____call_usermodehelper() (the child) 82 * does a little before exec/exit and it can't be frozen before waking up the 83 * parent. 84 */ 85 86 /* 87 * If the current task is a user space one, tell the freezer not to count it as 88 * freezable. 89 */ 90 static inline void freezer_do_not_count(void) 91 { 92 if (current->mm) 93 current->flags |= PF_FREEZER_SKIP; 94 } 95 96 /* 97 * If the current task is a user space one, tell the freezer to count it as 98 * freezable again and try to freeze it. 99 */ 100 static inline void freezer_count(void) 101 { 102 if (current->mm) { 103 current->flags &= ~PF_FREEZER_SKIP; 104 try_to_freeze(); 105 } 106 } 107 108 /* 109 * Check if the task should be counted as freezeable by the freezer 110 */ 111 static inline int freezer_should_skip(struct task_struct *p) 112 { 113 return !!(p->flags & PF_FREEZER_SKIP); 114 } 115 116 /* 117 * Tell the freezer that the current task should be frozen by it 118 */ 119 static inline void set_freezable(void) 120 { 121 current->flags &= ~PF_NOFREEZE; 122 } 123 124 /* 125 * Tell the freezer that the current task should be frozen by it and that it 126 * should send a fake signal to the task to freeze it. 127 */ 128 static inline void set_freezable_with_signal(void) 129 { 130 current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG); 131 } 132 133 /* 134 * Freezer-friendly wrappers around wait_event_interruptible() and 135 * wait_event_interruptible_timeout(), originally defined in <linux/wait.h> 136 */ 137 138 #define wait_event_freezable(wq, condition) \ 139 ({ \ 140 int __retval; \ 141 do { \ 142 __retval = wait_event_interruptible(wq, \ 143 (condition) || freezing(current)); \ 144 if (__retval && !freezing(current)) \ 145 break; \ 146 else if (!(condition)) \ 147 __retval = -ERESTARTSYS; \ 148 } while (try_to_freeze()); \ 149 __retval; \ 150 }) 151 152 153 #define wait_event_freezable_timeout(wq, condition, timeout) \ 154 ({ \ 155 long __retval = timeout; \ 156 do { \ 157 __retval = wait_event_interruptible_timeout(wq, \ 158 (condition) || freezing(current), \ 159 __retval); \ 160 } while (try_to_freeze()); \ 161 __retval; \ 162 }) 163 #else /* !CONFIG_FREEZER */ 164 static inline int frozen(struct task_struct *p) { return 0; } 165 static inline int freezing(struct task_struct *p) { return 0; } 166 static inline void set_freeze_flag(struct task_struct *p) {} 167 static inline void clear_freeze_flag(struct task_struct *p) {} 168 static inline int thaw_process(struct task_struct *p) { return 1; } 169 170 static inline void refrigerator(void) {} 171 static inline int freeze_processes(void) { BUG(); return 0; } 172 static inline void thaw_processes(void) {} 173 174 static inline int try_to_freeze(void) { return 0; } 175 176 static inline void freezer_do_not_count(void) {} 177 static inline void freezer_count(void) {} 178 static inline int freezer_should_skip(struct task_struct *p) { return 0; } 179 static inline void set_freezable(void) {} 180 static inline void set_freezable_with_signal(void) {} 181 182 #define wait_event_freezable(wq, condition) \ 183 wait_event_interruptible(wq, condition) 184 185 #define wait_event_freezable_timeout(wq, condition, timeout) \ 186 wait_event_interruptible_timeout(wq, condition, timeout) 187 188 #endif /* !CONFIG_FREEZER */ 189 190 #endif /* FREEZER_H_INCLUDED */ 191