freezer.h (9193B)
1/* SPDX-License-Identifier: GPL-2.0 */ 2/* Freezer declarations */ 3 4#ifndef FREEZER_H_INCLUDED 5#define FREEZER_H_INCLUDED 6 7#include <linux/debug_locks.h> 8#include <linux/sched.h> 9#include <linux/wait.h> 10#include <linux/atomic.h> 11 12#ifdef CONFIG_FREEZER 13extern atomic_t system_freezing_cnt; /* nr of freezing conds in effect */ 14extern bool pm_freezing; /* PM freezing in effect */ 15extern bool pm_nosig_freezing; /* PM nosig freezing in effect */ 16 17/* 18 * Timeout for stopping processes 19 */ 20extern unsigned int freeze_timeout_msecs; 21 22/* 23 * Check if a process has been frozen 24 */ 25static inline bool frozen(struct task_struct *p) 26{ 27 return p->flags & PF_FROZEN; 28} 29 30extern bool freezing_slow_path(struct task_struct *p); 31 32/* 33 * Check if there is a request to freeze a process 34 */ 35static inline bool freezing(struct task_struct *p) 36{ 37 if (likely(!atomic_read(&system_freezing_cnt))) 38 return false; 39 return freezing_slow_path(p); 40} 41 42/* Takes and releases task alloc lock using task_lock() */ 43extern void __thaw_task(struct task_struct *t); 44 45extern bool __refrigerator(bool check_kthr_stop); 46extern int freeze_processes(void); 47extern int freeze_kernel_threads(void); 48extern void thaw_processes(void); 49extern void thaw_kernel_threads(void); 50 51/* 52 * DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION 53 * If try_to_freeze causes a lockdep warning it means the caller may deadlock 54 */ 55static inline bool try_to_freeze_unsafe(void) 56{ 57 might_sleep(); 58 if (likely(!freezing(current))) 59 return false; 60 return __refrigerator(false); 61} 62 63static inline bool try_to_freeze(void) 64{ 65 if (!(current->flags & PF_NOFREEZE)) 66 debug_check_no_locks_held(); 67 return try_to_freeze_unsafe(); 68} 69 70extern bool freeze_task(struct task_struct *p); 71extern bool set_freezable(void); 72 73#ifdef CONFIG_CGROUP_FREEZER 74extern bool cgroup_freezing(struct task_struct *task); 75#else /* !CONFIG_CGROUP_FREEZER */ 76static inline bool cgroup_freezing(struct task_struct *task) 77{ 78 return false; 79} 80#endif /* !CONFIG_CGROUP_FREEZER */ 81 82/* 83 * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it 84 * calls wait_for_completion(&vfork) and reset right after it returns from this 85 * function. Next, the parent should call try_to_freeze() to freeze itself 86 * appropriately in case the child has exited before the freezing of tasks is 87 * complete. However, we don't want kernel threads to be frozen in unexpected 88 * places, so we allow them to block freeze_processes() instead or to set 89 * PF_NOFREEZE if needed. Fortunately, in the ____call_usermodehelper() case the 90 * parent won't really block freeze_processes(), since ____call_usermodehelper() 91 * (the child) does a little before exec/exit and it can't be frozen before 92 * waking up the parent. 93 */ 94 95 96/** 97 * freezer_do_not_count - tell freezer to ignore %current 98 * 99 * Tell freezers to ignore the current task when determining whether the 100 * target frozen state is reached. IOW, the current task will be 101 * considered frozen enough by freezers. 102 * 103 * The caller shouldn't do anything which isn't allowed for a frozen task 104 * until freezer_cont() is called. Usually, freezer[_do_not]_count() pair 105 * wrap a scheduling operation and nothing much else. 106 */ 107static inline void freezer_do_not_count(void) 108{ 109 current->flags |= PF_FREEZER_SKIP; 110} 111 112/** 113 * freezer_count - tell freezer to stop ignoring %current 114 * 115 * Undo freezer_do_not_count(). It tells freezers that %current should be 116 * considered again and tries to freeze if freezing condition is already in 117 * effect. 118 */ 119static inline void freezer_count(void) 120{ 121 current->flags &= ~PF_FREEZER_SKIP; 122 /* 123 * If freezing is in progress, the following paired with smp_mb() 124 * in freezer_should_skip() ensures that either we see %true 125 * freezing() or freezer_should_skip() sees !PF_FREEZER_SKIP. 126 */ 127 smp_mb(); 128 try_to_freeze(); 129} 130 131/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ 132static inline void freezer_count_unsafe(void) 133{ 134 current->flags &= ~PF_FREEZER_SKIP; 135 smp_mb(); 136 try_to_freeze_unsafe(); 137} 138 139/** 140 * freezer_should_skip - whether to skip a task when determining frozen 141 * state is reached 142 * @p: task in quesion 143 * 144 * This function is used by freezers after establishing %true freezing() to 145 * test whether a task should be skipped when determining the target frozen 146 * state is reached. IOW, if this function returns %true, @p is considered 147 * frozen enough. 148 */ 149static inline bool freezer_should_skip(struct task_struct *p) 150{ 151 /* 152 * The following smp_mb() paired with the one in freezer_count() 153 * ensures that either freezer_count() sees %true freezing() or we 154 * see cleared %PF_FREEZER_SKIP and return %false. This makes it 155 * impossible for a task to slip frozen state testing after 156 * clearing %PF_FREEZER_SKIP. 157 */ 158 smp_mb(); 159 return p->flags & PF_FREEZER_SKIP; 160} 161 162/* 163 * These functions are intended to be used whenever you want allow a sleeping 164 * task to be frozen. Note that neither return any clear indication of 165 * whether a freeze event happened while in this function. 166 */ 167 168/* Like schedule(), but should not block the freezer. */ 169static inline void freezable_schedule(void) 170{ 171 freezer_do_not_count(); 172 schedule(); 173 freezer_count(); 174} 175 176/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ 177static inline void freezable_schedule_unsafe(void) 178{ 179 freezer_do_not_count(); 180 schedule(); 181 freezer_count_unsafe(); 182} 183 184/* 185 * Like schedule_timeout(), but should not block the freezer. Do not 186 * call this with locks held. 187 */ 188static inline long freezable_schedule_timeout(long timeout) 189{ 190 long __retval; 191 freezer_do_not_count(); 192 __retval = schedule_timeout(timeout); 193 freezer_count(); 194 return __retval; 195} 196 197/* 198 * Like schedule_timeout_interruptible(), but should not block the freezer. Do not 199 * call this with locks held. 200 */ 201static inline long freezable_schedule_timeout_interruptible(long timeout) 202{ 203 long __retval; 204 freezer_do_not_count(); 205 __retval = schedule_timeout_interruptible(timeout); 206 freezer_count(); 207 return __retval; 208} 209 210/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ 211static inline long freezable_schedule_timeout_interruptible_unsafe(long timeout) 212{ 213 long __retval; 214 215 freezer_do_not_count(); 216 __retval = schedule_timeout_interruptible(timeout); 217 freezer_count_unsafe(); 218 return __retval; 219} 220 221/* Like schedule_timeout_killable(), but should not block the freezer. */ 222static inline long freezable_schedule_timeout_killable(long timeout) 223{ 224 long __retval; 225 freezer_do_not_count(); 226 __retval = schedule_timeout_killable(timeout); 227 freezer_count(); 228 return __retval; 229} 230 231/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ 232static inline long freezable_schedule_timeout_killable_unsafe(long timeout) 233{ 234 long __retval; 235 freezer_do_not_count(); 236 __retval = schedule_timeout_killable(timeout); 237 freezer_count_unsafe(); 238 return __retval; 239} 240 241/* 242 * Like schedule_hrtimeout_range(), but should not block the freezer. Do not 243 * call this with locks held. 244 */ 245static inline int freezable_schedule_hrtimeout_range(ktime_t *expires, 246 u64 delta, const enum hrtimer_mode mode) 247{ 248 int __retval; 249 freezer_do_not_count(); 250 __retval = schedule_hrtimeout_range(expires, delta, mode); 251 freezer_count(); 252 return __retval; 253} 254 255/* 256 * Freezer-friendly wrappers around wait_event_interruptible(), 257 * wait_event_killable() and wait_event_interruptible_timeout(), originally 258 * defined in <linux/wait.h> 259 */ 260 261/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ 262#define wait_event_freezekillable_unsafe(wq, condition) \ 263({ \ 264 int __retval; \ 265 freezer_do_not_count(); \ 266 __retval = wait_event_killable(wq, (condition)); \ 267 freezer_count_unsafe(); \ 268 __retval; \ 269}) 270 271#else /* !CONFIG_FREEZER */ 272static inline bool frozen(struct task_struct *p) { return false; } 273static inline bool freezing(struct task_struct *p) { return false; } 274static inline void __thaw_task(struct task_struct *t) {} 275 276static inline bool __refrigerator(bool check_kthr_stop) { return false; } 277static inline int freeze_processes(void) { return -ENOSYS; } 278static inline int freeze_kernel_threads(void) { return -ENOSYS; } 279static inline void thaw_processes(void) {} 280static inline void thaw_kernel_threads(void) {} 281 282static inline bool try_to_freeze(void) { return false; } 283 284static inline void freezer_do_not_count(void) {} 285static inline void freezer_count(void) {} 286static inline int freezer_should_skip(struct task_struct *p) { return 0; } 287static inline void set_freezable(void) {} 288 289#define freezable_schedule() schedule() 290 291#define freezable_schedule_unsafe() schedule() 292 293#define freezable_schedule_timeout(timeout) schedule_timeout(timeout) 294 295#define freezable_schedule_timeout_interruptible(timeout) \ 296 schedule_timeout_interruptible(timeout) 297 298#define freezable_schedule_timeout_interruptible_unsafe(timeout) \ 299 schedule_timeout_interruptible(timeout) 300 301#define freezable_schedule_timeout_killable(timeout) \ 302 schedule_timeout_killable(timeout) 303 304#define freezable_schedule_timeout_killable_unsafe(timeout) \ 305 schedule_timeout_killable(timeout) 306 307#define freezable_schedule_hrtimeout_range(expires, delta, mode) \ 308 schedule_hrtimeout_range(expires, delta, mode) 309 310#define wait_event_freezekillable_unsafe(wq, condition) \ 311 wait_event_killable(wq, condition) 312 313#endif /* !CONFIG_FREEZER */ 314 315#endif /* FREEZER_H_INCLUDED */