include/linux/cpuset.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_CPUSET_H
   3 #define _LINUX_CPUSET_H
   4 /*
   5  *  cpuset interface
   6  *
   7  *  Copyright (C) 2003 BULL SA
   8  *  Copyright (C) 2004-2006 Silicon Graphics, Inc.
   9  *
  10  */
  11
  12 #include <linux/sched.h>
  13 #include <linux/sched/topology.h>
  14 #include <linux/sched/task.h>
  15 #include <linux/cpumask.h>
  16 #include <linux/nodemask.h>
  17 #include <linux/mm.h>
  18 #include <linux/jump_label.h>
  19
  20 #ifdef CONFIG_CPUSETS
  21
  22 /*
  23  * Static branch rewrites can happen in an arbitrary order for a given
  24  * key. In code paths where we need to loop with read_mems_allowed_begin() and
  25  * read_mems_allowed_retry() to get a consistent view of mems_allowed, we need
  26  * to ensure that begin() always gets rewritten before retry() in the
  27  * disabled -> enabled transition. If not, then if local irqs are disabled
  28  * around the loop, we can deadlock since retry() would always be
  29  * comparing the latest value of the mems_allowed seqcount against 0 as
  30  * begin() still would see cpusets_enabled() as false. The enabled -> disabled
  31  * transition should happen in reverse order for the same reasons (want to stop
  32  * looking at real value of mems_allowed.sequence in retry() first).
  33  */
  34 extern struct static_key_false cpusets_pre_enable_key;
  35 extern struct static_key_false cpusets_enabled_key;
  36 static inline bool cpusets_enabled(void)
  37 {
  38         return static_branch_unlikely(&cpusets_enabled_key);
  39 }
  40
  41 static inline void cpuset_inc(void)
  42 {
  43         static_branch_inc_cpuslocked(&cpusets_pre_enable_key);
  44         static_branch_inc_cpuslocked(&cpusets_enabled_key);
  45 }
  46
  47 static inline void cpuset_dec(void)
  48 {
  49         static_branch_dec_cpuslocked(&cpusets_enabled_key);
  50         static_branch_dec_cpuslocked(&cpusets_pre_enable_key);
  51 }
  52
  53 extern int cpuset_init(void);
  54 extern void cpuset_init_smp(void);
  55 extern void cpuset_force_rebuild(void);
  56 extern void cpuset_update_active_cpus(void);
  57 extern void cpuset_read_lock(void);
  58 extern void cpuset_read_unlock(void);
  59 extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
  60 extern void cpuset_cpus_allowed_fallback(struct task_struct *p);
  61 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
  62 #define cpuset_current_mems_allowed (current->mems_allowed)
  63 void cpuset_init_current_mems_allowed(void);
  64 int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
  65
  66 extern bool __cpuset_node_allowed(int node, gfp_t gfp_mask);
  67
  68 static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
  69 {
  70         if (cpusets_enabled())
  71                 return __cpuset_node_allowed(node, gfp_mask);
  72         return true;
  73 }
  74
  75 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
  76 {
  77         return __cpuset_node_allowed(zone_to_nid(z), gfp_mask);
  78 }
  79
  80 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
  81 {
  82         if (cpusets_enabled())
  83                 return __cpuset_zone_allowed(z, gfp_mask);
  84         return true;
  85 }
  86
  87 extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
  88                                           const struct task_struct *tsk2);
  89
  90 #define cpuset_memory_pressure_bump()                           \
  91         do {                                                    \
  92                 if (cpuset_memory_pressure_enabled)             \
  93                         __cpuset_memory_pressure_bump();        \
  94         } while (0)
  95 extern int cpuset_memory_pressure_enabled;
  96 extern void __cpuset_memory_pressure_bump(void);
  97
  98 extern void cpuset_task_status_allowed(struct seq_file *m,
  99                                         struct task_struct *task);
 100 extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
 101                             struct pid *pid, struct task_struct *tsk);
 102
 103 extern int cpuset_mem_spread_node(void);
 104 extern int cpuset_slab_spread_node(void);
 105
 106 static inline int cpuset_do_page_mem_spread(void)
 107 {
 108         return task_spread_page(current);
 109 }
 110
 111 static inline int cpuset_do_slab_mem_spread(void)
 112 {
 113         return task_spread_slab(current);
 114 }
 115
 116 extern bool current_cpuset_is_being_rebound(void);
 117
 118 extern void rebuild_sched_domains(void);
 119
 120 extern void cpuset_print_current_mems_allowed(void);
 121
 122 /*
 123  * read_mems_allowed_begin is required when making decisions involving
 124  * mems_allowed such as during page allocation. mems_allowed can be updated in
 125  * parallel and depending on the new value an operation can fail potentially
 126  * causing process failure. A retry loop with read_mems_allowed_begin and
 127  * read_mems_allowed_retry prevents these artificial failures.
 128  */
 129 static inline unsigned int read_mems_allowed_begin(void)
 130 {
 131         if (!static_branch_unlikely(&cpusets_pre_enable_key))
 132                 return 0;
 133
 134         return read_seqcount_begin(&current->mems_allowed_seq);
 135 }
 136
 137 /*
 138  * If this returns true, the operation that took place after
 139  * read_mems_allowed_begin may have failed artificially due to a concurrent
 140  * update of mems_allowed. It is up to the caller to retry the operation if
 141  * appropriate.
 142  */
 143 static inline bool read_mems_allowed_retry(unsigned int seq)
 144 {
 145         if (!static_branch_unlikely(&cpusets_enabled_key))
 146                 return false;
 147
 148         return read_seqcount_retry(&current->mems_allowed_seq, seq);
 149 }
 150
 151 static inline void set_mems_allowed(nodemask_t nodemask)
 152 {
 153         unsigned long flags;
 154
 155         task_lock(current);
 156         local_irq_save(flags);
 157         write_seqcount_begin(&current->mems_allowed_seq);
 158         current->mems_allowed = nodemask;
 159         write_seqcount_end(&current->mems_allowed_seq);
 160         local_irq_restore(flags);
 161         task_unlock(current);
 162 }
 163
 164 #else /* !CONFIG_CPUSETS */
 165
 166 static inline bool cpusets_enabled(void) { return false; }
 167
 168 static inline int cpuset_init(void) { return 0; }
 169 static inline void cpuset_init_smp(void) {}
 170
 171 static inline void cpuset_force_rebuild(void) { }
 172
 173 static inline void cpuset_update_active_cpus(void)
 174 {
 175         partition_sched_domains(1, NULL, NULL);
 176 }
 177
 178 static inline void cpuset_read_lock(void) { }
 179 static inline void cpuset_read_unlock(void) { }
 180
 181 static inline void cpuset_cpus_allowed(struct task_struct *p,
 182                                        struct cpumask *mask)
 183 {
 184         cpumask_copy(mask, cpu_possible_mask);
 185 }
 186
 187 static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
 188 {
 189 }
 190
 191 static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
 192 {
 193         return node_possible_map;
 194 }
 195
 196 #define cpuset_current_mems_allowed (node_states[N_MEMORY])
 197 static inline void cpuset_init_current_mems_allowed(void) {}
 198
 199 static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
 200 {
 201         return 1;
 202 }
 203
 204 static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
 205 {
 206         return true;
 207 }
 208
 209 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 210 {
 211         return true;
 212 }
 213
 214 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 215 {
 216         return true;
 217 }
 218
 219 static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
 220                                                  const struct task_struct *tsk2)
 221 {
 222         return 1;
 223 }
 224
 225 static inline void cpuset_memory_pressure_bump(void) {}
 226
 227 static inline void cpuset_task_status_allowed(struct seq_file *m,
 228                                                 struct task_struct *task)
 229 {
 230 }
 231
 232 static inline int cpuset_mem_spread_node(void)
 233 {
 234         return 0;
 235 }
 236
 237 static inline int cpuset_slab_spread_node(void)
 238 {
 239         return 0;
 240 }
 241
 242 static inline int cpuset_do_page_mem_spread(void)
 243 {
 244         return 0;
 245 }
 246
 247 static inline int cpuset_do_slab_mem_spread(void)
 248 {
 249         return 0;
 250 }
 251
 252 static inline bool current_cpuset_is_being_rebound(void)
 253 {
 254         return false;
 255 }
 256
 257 static inline void rebuild_sched_domains(void)
 258 {
 259         partition_sched_domains(1, NULL, NULL);
 260 }
 261
 262 static inline void cpuset_print_current_mems_allowed(void)
 263 {
 264 }
 265
 266 static inline void set_mems_allowed(nodemask_t nodemask)
 267 {
 268 }
 269
 270 static inline unsigned int read_mems_allowed_begin(void)
 271 {
 272         return 0;
 273 }
 274
 275 static inline bool read_mems_allowed_retry(unsigned int seq)
 276 {
 277         return false;
 278 }
 279
 280 #endif /* !CONFIG_CPUSETS */
 281
 282 #endif /* _LINUX_CPUSET_H */