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 */
35extern struct static_key_false cpusets_pre_enable_key;
36extern struct static_key_false cpusets_enabled_key;
37extern struct static_key_false cpusets_insane_config_key;
38
39static inline bool cpusets_enabled(void)
40{
41 return static_branch_unlikely(&cpusets_enabled_key);
42}
43
44static 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
50static 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 */
64static inline bool cpusets_insane_config(void)
65{
66 return static_branch_unlikely(&cpusets_insane_config_key);
67}
68
69extern int cpuset_init(void);
70extern void cpuset_init_smp(void);
71extern void cpuset_force_rebuild(void);
72extern void cpuset_update_active_cpus(void);
73extern void cpuset_wait_for_hotplug(void);
74extern void cpuset_read_lock(void);
75extern void cpuset_read_unlock(void);
76extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
77extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);
78extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
79#define cpuset_current_mems_allowed (current->mems_allowed)
80void cpuset_init_current_mems_allowed(void);
81int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
82
83extern bool __cpuset_node_allowed(int node, gfp_t gfp_mask);
84
85static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
86{
87 if (cpusets_enabled())
88 return __cpuset_node_allowed(node, gfp_mask);
89 return true;
90}
91
92static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
93{
94 return __cpuset_node_allowed(zone_to_nid(z), gfp_mask);
95}
96
97static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
98{
99 if (cpusets_enabled())
100 return __cpuset_zone_allowed(z, gfp_mask);
101 return true;
102}
103
104extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
105 const struct task_struct *tsk2);
106
107#define cpuset_memory_pressure_bump() \
108 do { \
109 if (cpuset_memory_pressure_enabled) \
110 __cpuset_memory_pressure_bump(); \
111 } while (0)
112extern int cpuset_memory_pressure_enabled;
113extern void __cpuset_memory_pressure_bump(void);
114
115extern void cpuset_task_status_allowed(struct seq_file *m,
116 struct task_struct *task);
117extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
118 struct pid *pid, struct task_struct *tsk);
119
120extern int cpuset_mem_spread_node(void);
121extern int cpuset_slab_spread_node(void);
122
123static inline int cpuset_do_page_mem_spread(void)
124{
125 return task_spread_page(current);
126}
127
128static inline int cpuset_do_slab_mem_spread(void)
129{
130 return task_spread_slab(current);
131}
132
133extern bool current_cpuset_is_being_rebound(void);
134
135extern void rebuild_sched_domains(void);
136
137extern void cpuset_print_current_mems_allowed(void);
138
139/*
140 * read_mems_allowed_begin is required when making decisions involving
141 * mems_allowed such as during page allocation. mems_allowed can be updated in
142 * parallel and depending on the new value an operation can fail potentially
143 * causing process failure. A retry loop with read_mems_allowed_begin and
144 * read_mems_allowed_retry prevents these artificial failures.
145 */
146static inline unsigned int read_mems_allowed_begin(void)
147{
148 if (!static_branch_unlikely(&cpusets_pre_enable_key))
149 return 0;
150
151 return read_seqcount_begin(&current->mems_allowed_seq);
152}
153
154/*
155 * If this returns true, the operation that took place after
156 * read_mems_allowed_begin may have failed artificially due to a concurrent
157 * update of mems_allowed. It is up to the caller to retry the operation if
158 * appropriate.
159 */
160static inline bool read_mems_allowed_retry(unsigned int seq)
161{
162 if (!static_branch_unlikely(&cpusets_enabled_key))
163 return false;
164
165 return read_seqcount_retry(&current->mems_allowed_seq, seq);
166}
167
168static inline void set_mems_allowed(nodemask_t nodemask)
169{
170 unsigned long flags;
171
172 task_lock(current);
173 local_irq_save(flags);
174 write_seqcount_begin(&current->mems_allowed_seq);
175 current->mems_allowed = nodemask;
176 write_seqcount_end(&current->mems_allowed_seq);
177 local_irq_restore(flags);
178 task_unlock(current);
179}
180
181#else /* !CONFIG_CPUSETS */
182
183static inline bool cpusets_enabled(void) { return false; }
184
185static inline bool cpusets_insane_config(void) { return false; }
186
187static inline int cpuset_init(void) { return 0; }
188static inline void cpuset_init_smp(void) {}
189
190static inline void cpuset_force_rebuild(void) { }
191
192static inline void cpuset_update_active_cpus(void)
193{
194 partition_sched_domains(1, NULL, NULL);
195}
196
197static inline void cpuset_wait_for_hotplug(void) { }
198
199static inline void cpuset_read_lock(void) { }
200static inline void cpuset_read_unlock(void) { }
201
202static inline void cpuset_cpus_allowed(struct task_struct *p,
203 struct cpumask *mask)
204{
205 cpumask_copy(mask, task_cpu_possible_mask(p));
206}
207
208static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p)
209{
210 return false;
211}
212
213static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
214{
215 return node_possible_map;
216}
217
218#define cpuset_current_mems_allowed (node_states[N_MEMORY])
219static inline void cpuset_init_current_mems_allowed(void) {}
220
221static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
222{
223 return 1;
224}
225
226static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
227{
228 return true;
229}
230
231static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
232{
233 return true;
234}
235
236static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
237{
238 return true;
239}
240
241static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
242 const struct task_struct *tsk2)
243{
244 return 1;
245}
246
247static inline void cpuset_memory_pressure_bump(void) {}
248
249static inline void cpuset_task_status_allowed(struct seq_file *m,
250 struct task_struct *task)
251{
252}
253
254static inline int cpuset_mem_spread_node(void)
255{
256 return 0;
257}
258
259static inline int cpuset_slab_spread_node(void)
260{
261 return 0;
262}
263
264static inline int cpuset_do_page_mem_spread(void)
265{
266 return 0;
267}
268
269static inline int cpuset_do_slab_mem_spread(void)
270{
271 return 0;
272}
273
274static inline bool current_cpuset_is_being_rebound(void)
275{
276 return false;
277}
278
279static inline void rebuild_sched_domains(void)
280{
281 partition_sched_domains(1, NULL, NULL);
282}
283
284static inline void cpuset_print_current_mems_allowed(void)
285{
286}
287
288static inline void set_mems_allowed(nodemask_t nodemask)
289{
290}
291
292static inline unsigned int read_mems_allowed_begin(void)
293{
294 return 0;
295}
296
297static inline bool read_mems_allowed_retry(unsigned int seq)
298{
299 return false;
300}
301
302#endif /* !CONFIG_CPUSETS */
303
304#endif /* _LINUX_CPUSET_H */
305

source code of linux/include/linux/cpuset.h