include/linux/cpuset.h

   1 #ifndef _LINUX_CPUSET_H
   2 #define _LINUX_CPUSET_H
   3 /*
   4  *  cpuset interface
   5  *
   6  *  Copyright (C) 2003 BULL SA
   7  *  Copyright (C) 2004-2006 Silicon Graphics, Inc.
   8  *
   9  */
  10
  11 #include <linux/sched.h>
  12 #include <linux/sched/topology.h>
  13 #include <linux/sched/task.h>
  14 #include <linux/cpumask.h>
  15 #include <linux/nodemask.h>
  16 #include <linux/mm.h>
  17 #include <linux/jump_label.h>
  18
  19 #ifdef CONFIG_CPUSETS
  20
  21 /*
  22  * Static branch rewrites can happen in an arbitrary order for a given
  23  * key. In code paths where we need to loop with read_mems_allowed_begin() and
  24  * read_mems_allowed_retry() to get a consistent view of mems_allowed, we need
  25  * to ensure that begin() always gets rewritten before retry() in the
  26  * disabled -> enabled transition. If not, then if local irqs are disabled
  27  * around the loop, we can deadlock since retry() would always be
  28  * comparing the latest value of the mems_allowed seqcount against 0 as
  29  * begin() still would see cpusets_enabled() as false. The enabled -> disabled
  30  * transition should happen in reverse order for the same reasons (want to stop
  31  * looking at real value of mems_allowed.sequence in retry() first).
  32  */
  33 extern struct static_key_false cpusets_pre_enable_key;
  34 extern struct static_key_false cpusets_enabled_key;
  35 static inline bool cpusets_enabled(void)
  36 {
  37         return static_branch_unlikely(&cpusets_enabled_key);
  38 }
  39
  40 static inline int nr_cpusets(void)
  41 {
  42         /* jump label reference count + the top-level cpuset */
  43         return static_key_count(&cpusets_enabled_key.key) + 1;
  44 }
  45
  46 static inline void cpuset_inc(void)
  47 {
  48         static_branch_inc(&cpusets_pre_enable_key);
  49         static_branch_inc(&cpusets_enabled_key);
  50 }
  51
  52 static inline void cpuset_dec(void)
  53 {
  54         static_branch_dec(&cpusets_enabled_key);
  55         static_branch_dec(&cpusets_pre_enable_key);
  56 }
  57
  58 extern int cpuset_init(void);
  59 extern void cpuset_init_smp(void);
  60 extern void cpuset_force_rebuild(void);
  61 extern void cpuset_update_active_cpus(void);
  62 extern void cpuset_wait_for_hotplug(void);
  63 extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
  64 extern void cpuset_cpus_allowed_fallback(struct task_struct *p);
  65 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
  66 #define cpuset_current_mems_allowed (current->mems_allowed)
  67 void cpuset_init_current_mems_allowed(void);
  68 int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
  69
  70 extern bool __cpuset_node_allowed(int node, gfp_t gfp_mask);
  71
  72 static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
  73 {
  74         if (cpusets_enabled())
  75                 return __cpuset_node_allowed(node, gfp_mask);
  76         return true;
  77 }
  78
  79 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
  80 {
  81         return __cpuset_node_allowed(zone_to_nid(z), gfp_mask);
  82 }
  83
  84 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
  85 {
  86         if (cpusets_enabled())
  87                 return __cpuset_zone_allowed(z, gfp_mask);
  88         return true;
  89 }
  90
  91 extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
  92                                           const struct task_struct *tsk2);
  93
  94 #define cpuset_memory_pressure_bump()                           \
  95         do {                                                    \
  96                 if (cpuset_memory_pressure_enabled)             \
  97                         __cpuset_memory_pressure_bump();        \
  98         } while (0)
  99 extern int cpuset_memory_pressure_enabled;
 100 extern void __cpuset_memory_pressure_bump(void);
 101
 102 extern void cpuset_task_status_allowed(struct seq_file *m,
 103                                         struct task_struct *task);
 104 extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
 105                             struct pid *pid, struct task_struct *tsk);
 106
 107 extern int cpuset_mem_spread_node(void);
 108 extern int cpuset_slab_spread_node(void);
 109
 110 static inline int cpuset_do_page_mem_spread(void)
 111 {
 112         return task_spread_page(current);
 113 }
 114
 115 static inline int cpuset_do_slab_mem_spread(void)
 116 {
 117         return task_spread_slab(current);
 118 }
 119
 120 extern int current_cpuset_is_being_rebound(void);
 121
 122 extern void rebuild_sched_domains(void);
 123
 124 extern void cpuset_print_current_mems_allowed(void);
 125
 126 /*
 127  * read_mems_allowed_begin is required when making decisions involving
 128  * mems_allowed such as during page allocation. mems_allowed can be updated in
 129  * parallel and depending on the new value an operation can fail potentially
 130  * causing process failure. A retry loop with read_mems_allowed_begin and
 131  * read_mems_allowed_retry prevents these artificial failures.
 132  */
 133 static inline unsigned int read_mems_allowed_begin(void)
 134 {
 135         if (!static_branch_unlikely(&cpusets_pre_enable_key))
 136                 return 0;
 137
 138         return read_seqcount_begin(&current->mems_allowed_seq);
 139 }
 140
 141 /*
 142  * If this returns true, the operation that took place after
 143  * read_mems_allowed_begin may have failed artificially due to a concurrent
 144  * update of mems_allowed. It is up to the caller to retry the operation if
 145  * appropriate.
 146  */
 147 static inline bool read_mems_allowed_retry(unsigned int seq)
 148 {
 149         if (!static_branch_unlikely(&cpusets_enabled_key))
 150                 return false;
 151
 152         return read_seqcount_retry(&current->mems_allowed_seq, seq);
 153 }
 154
 155 static inline void set_mems_allowed(nodemask_t nodemask)
 156 {
 157         unsigned long flags;
 158
 159         task_lock(current);
 160         local_irq_save(flags);
 161         write_seqcount_begin(&current->mems_allowed_seq);
 162         current->mems_allowed = nodemask;
 163         write_seqcount_end(&current->mems_allowed_seq);
 164         local_irq_restore(flags);
 165         task_unlock(current);
 166 }
 167
 168 #else /* !CONFIG_CPUSETS */
 169
 170 static inline bool cpusets_enabled(void) { return false; }
 171
 172 static inline int cpuset_init(void) { return 0; }
 173 static inline void cpuset_init_smp(void) {}
 174
 175 static inline void cpuset_force_rebuild(void) { }
 176
 177 static inline void cpuset_update_active_cpus(void)
 178 {
 179         partition_sched_domains(1, NULL, NULL);
 180 }
 181
 182 static inline void cpuset_wait_for_hotplug(void) { }
 183
 184 static inline void cpuset_cpus_allowed(struct task_struct *p,
 185                                        struct cpumask *mask)
 186 {
 187         cpumask_copy(mask, cpu_possible_mask);
 188 }
 189
 190 static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
 191 {
 192 }
 193
 194 static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
 195 {
 196         return node_possible_map;
 197 }
 198
 199 #define cpuset_current_mems_allowed (node_states[N_MEMORY])
 200 static inline void cpuset_init_current_mems_allowed(void) {}
 201
 202 static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
 203 {
 204         return 1;
 205 }
 206
 207 static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
 208 {
 209         return true;
 210 }
 211
 212 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 213 {
 214         return true;
 215 }
 216
 217 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 218 {
 219         return true;
 220 }
 221
 222 static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
 223                                                  const struct task_struct *tsk2)
 224 {
 225         return 1;
 226 }
 227
 228 static inline void cpuset_memory_pressure_bump(void) {}
 229
 230 static inline void cpuset_task_status_allowed(struct seq_file *m,
 231                                                 struct task_struct *task)
 232 {
 233 }
 234
 235 static inline int cpuset_mem_spread_node(void)
 236 {
 237         return 0;
 238 }
 239
 240 static inline int cpuset_slab_spread_node(void)
 241 {
 242         return 0;
 243 }
 244
 245 static inline int cpuset_do_page_mem_spread(void)
 246 {
 247         return 0;
 248 }
 249
 250 static inline int cpuset_do_slab_mem_spread(void)
 251 {
 252         return 0;
 253 }
 254
 255 static inline int current_cpuset_is_being_rebound(void)
 256 {
 257         return 0;
 258 }
 259
 260 static inline void rebuild_sched_domains(void)
 261 {
 262         partition_sched_domains(1, NULL, NULL);
 263 }
 264
 265 static inline void cpuset_print_current_mems_allowed(void)
 266 {
 267 }
 268
 269 static inline void set_mems_allowed(nodemask_t nodemask)
 270 {
 271 }
 272
 273 static inline unsigned int read_mems_allowed_begin(void)
 274 {
 275         return 0;
 276 }
 277
 278 static inline bool read_mems_allowed_retry(unsigned int seq)
 279 {
 280         return false;
 281 }
 282
 283 #endif /* !CONFIG_CPUSETS */
 284
 285 #endif /* _LINUX_CPUSET_H */