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/mmu_context.h>
  19 #include <linux/jump_label.h>
  20
  21 #ifdef CONFIG_CPUSETS
  22
  23 /*
  24  * Static branch rewrites can happen in an arbitrary order for a given
  25  * key. In code paths where we need to loop with read_mems_allowed_begin() and
  26  * read_mems_allowed_retry() to get a consistent view of mems_allowed, we need
  27  * to ensure that begin() always gets rewritten before retry() in the
  28  * disabled -> enabled transition. If not, then if local irqs are disabled
  29  * around the loop, we can deadlock since retry() would always be
  30  * comparing the latest value of the mems_allowed seqcount against 0 as
  31  * begin() still would see cpusets_enabled() as false. The enabled -> disabled
  32  * transition should happen in reverse order for the same reasons (want to stop
  33  * looking at real value of mems_allowed.sequence in retry() first).
  34  */
  35 extern struct static_key_false cpusets_pre_enable_key;
  36 extern struct static_key_false cpusets_enabled_key;
  37 extern struct static_key_false cpusets_insane_config_key;
  38
  39 static inline bool cpusets_enabled(void)
  40 {
  41         return static_branch_unlikely(&cpusets_enabled_key);
  42 }
  43
  44 static inline void cpuset_inc(void)
  45 {
  46         static_branch_inc_cpuslocked(&cpusets_pre_enable_key);
  47         static_branch_inc_cpuslocked(&cpusets_enabled_key);
  48 }
  49
  50 static inline void cpuset_dec(void)
  51 {
  52         static_branch_dec_cpuslocked(&cpusets_enabled_key);
  53         static_branch_dec_cpuslocked(&cpusets_pre_enable_key);
  54 }
  55
  56 /*
  57  * This will get enabled whenever a cpuset configuration is considered
  58  * unsupportable in general. E.g. movable only node which cannot satisfy
  59  * any non movable allocations (see update_nodemask). Page allocator
  60  * needs to make additional checks for those configurations and this
  61  * check is meant to guard those checks without any overhead for sane
  62  * configurations.
  63  */
  64 static inline bool cpusets_insane_config(void)
  65 {
  66         return static_branch_unlikely(&cpusets_insane_config_key);
  67 }
  68
  69 extern int cpuset_init(void);
  70 extern void cpuset_init_smp(void);
  71 extern void cpuset_force_rebuild(void);
  72 extern void cpuset_update_active_cpus(void);
  73 extern void inc_dl_tasks_cs(struct task_struct *task);
  74 extern void dec_dl_tasks_cs(struct task_struct *task);
  75 extern void cpuset_lock(void);
  76 extern void cpuset_unlock(void);
  77 extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
  78 extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);
  79 extern bool cpuset_cpu_is_isolated(int cpu);
  80 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
  81 #define cpuset_current_mems_allowed (current->mems_allowed)
  82 void cpuset_init_current_mems_allowed(void);
  83 int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
  84
  85 extern bool cpuset_node_allowed(int node, gfp_t gfp_mask);
  86
  87 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
  88 {
  89         return cpuset_node_allowed(zone_to_nid(z), gfp_mask);
  90 }
  91
  92 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
  93 {
  94         if (cpusets_enabled())
  95                 return __cpuset_zone_allowed(z, gfp_mask);
  96         return true;
  97 }
  98
  99 extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
 100                                           const struct task_struct *tsk2);
 101
 102 #ifdef CONFIG_CPUSETS_V1
 103 #define cpuset_memory_pressure_bump()                           \
 104         do {                                                    \
 105                 if (cpuset_memory_pressure_enabled)             \
 106                         __cpuset_memory_pressure_bump();        \
 107         } while (0)
 108 extern int cpuset_memory_pressure_enabled;
 109 extern void __cpuset_memory_pressure_bump(void);
 110 #else
 111 static inline void cpuset_memory_pressure_bump(void) { }
 112 #endif
 113
 114 extern void cpuset_task_status_allowed(struct seq_file *m,
 115                                         struct task_struct *task);
 116 extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
 117                             struct pid *pid, struct task_struct *tsk);
 118
 119 extern int cpuset_mem_spread_node(void);
 120
 121 static inline int cpuset_do_page_mem_spread(void)
 122 {
 123         return task_spread_page(current);
 124 }
 125
 126 extern bool current_cpuset_is_being_rebound(void);
 127
 128 extern void rebuild_sched_domains(void);
 129
 130 extern void cpuset_print_current_mems_allowed(void);
 131
 132 /*
 133  * read_mems_allowed_begin is required when making decisions involving
 134  * mems_allowed such as during page allocation. mems_allowed can be updated in
 135  * parallel and depending on the new value an operation can fail potentially
 136  * causing process failure. A retry loop with read_mems_allowed_begin and
 137  * read_mems_allowed_retry prevents these artificial failures.
 138  */
 139 static inline unsigned int read_mems_allowed_begin(void)
 140 {
 141         if (!static_branch_unlikely(&cpusets_pre_enable_key))
 142                 return 0;
 143
 144         return read_seqcount_begin(&current->mems_allowed_seq);
 145 }
 146
 147 /*
 148  * If this returns true, the operation that took place after
 149  * read_mems_allowed_begin may have failed artificially due to a concurrent
 150  * update of mems_allowed. It is up to the caller to retry the operation if
 151  * appropriate.
 152  */
 153 static inline bool read_mems_allowed_retry(unsigned int seq)
 154 {
 155         if (!static_branch_unlikely(&cpusets_enabled_key))
 156                 return false;
 157
 158         return read_seqcount_retry(&current->mems_allowed_seq, seq);
 159 }
 160
 161 static inline void set_mems_allowed(nodemask_t nodemask)
 162 {
 163         unsigned long flags;
 164
 165         task_lock(current);
 166         local_irq_save(flags);
 167         write_seqcount_begin(&current->mems_allowed_seq);
 168         current->mems_allowed = nodemask;
 169         write_seqcount_end(&current->mems_allowed_seq);
 170         local_irq_restore(flags);
 171         task_unlock(current);
 172 }
 173
 174 #else /* !CONFIG_CPUSETS */
 175
 176 static inline bool cpusets_enabled(void) { return false; }
 177
 178 static inline bool cpusets_insane_config(void) { return false; }
 179
 180 static inline int cpuset_init(void) { return 0; }
 181 static inline void cpuset_init_smp(void) {}
 182
 183 static inline void cpuset_force_rebuild(void) { }
 184
 185 static inline void cpuset_update_active_cpus(void)
 186 {
 187         partition_sched_domains(1, NULL, NULL);
 188 }
 189
 190 static inline void inc_dl_tasks_cs(struct task_struct *task) { }
 191 static inline void dec_dl_tasks_cs(struct task_struct *task) { }
 192 static inline void cpuset_lock(void) { }
 193 static inline void cpuset_unlock(void) { }
 194
 195 static inline void cpuset_cpus_allowed(struct task_struct *p,
 196                                        struct cpumask *mask)
 197 {
 198         cpumask_copy(mask, task_cpu_possible_mask(p));
 199 }
 200
 201 static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p)
 202 {
 203         return false;
 204 }
 205
 206 static inline bool cpuset_cpu_is_isolated(int cpu)
 207 {
 208         return false;
 209 }
 210
 211 static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
 212 {
 213         return node_possible_map;
 214 }
 215
 216 #define cpuset_current_mems_allowed (node_states[N_MEMORY])
 217 static inline void cpuset_init_current_mems_allowed(void) {}
 218
 219 static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
 220 {
 221         return 1;
 222 }
 223
 224 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 225 {
 226         return true;
 227 }
 228
 229 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 230 {
 231         return true;
 232 }
 233
 234 static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
 235                                                  const struct task_struct *tsk2)
 236 {
 237         return 1;
 238 }
 239
 240 static inline void cpuset_memory_pressure_bump(void) {}
 241
 242 static inline void cpuset_task_status_allowed(struct seq_file *m,
 243                                                 struct task_struct *task)
 244 {
 245 }
 246
 247 static inline int cpuset_mem_spread_node(void)
 248 {
 249         return 0;
 250 }
 251
 252 static inline int cpuset_do_page_mem_spread(void)
 253 {
 254         return 0;
 255 }
 256
 257 static inline bool current_cpuset_is_being_rebound(void)
 258 {
 259         return false;
 260 }
 261
 262 static inline void rebuild_sched_domains(void)
 263 {
 264         partition_sched_domains(1, NULL, NULL);
 265 }
 266
 267 static inline void cpuset_print_current_mems_allowed(void)
 268 {
 269 }
 270
 271 static inline void set_mems_allowed(nodemask_t nodemask)
 272 {
 273 }
 274
 275 static inline unsigned int read_mems_allowed_begin(void)
 276 {
 277         return 0;
 278 }
 279
 280 static inline bool read_mems_allowed_retry(unsigned int seq)
 281 {
 282         return false;
 283 }
 284
 285 #endif /* !CONFIG_CPUSETS */
 286
 287 #endif /* _LINUX_CPUSET_H */