xref: /linux-6.15/include/linux/cpuset.h (revision f76fbbbb) 
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 static inline bool cpusets_enabled(void)
38 {
39 	return static_branch_unlikely(&cpusets_enabled_key);
40 }
41 
42 static inline void cpuset_inc(void)
43 {
44 	static_branch_inc_cpuslocked(&cpusets_pre_enable_key);
45 	static_branch_inc_cpuslocked(&cpusets_enabled_key);
46 }
47 
48 static inline void cpuset_dec(void)
49 {
50 	static_branch_dec_cpuslocked(&cpusets_enabled_key);
51 	static_branch_dec_cpuslocked(&cpusets_pre_enable_key);
52 }
53 
54 extern int cpuset_init(void);
55 extern void cpuset_init_smp(void);
56 extern void cpuset_force_rebuild(void);
57 extern void cpuset_update_active_cpus(void);
58 extern void cpuset_wait_for_hotplug(void);
59 extern void cpuset_read_lock(void);
60 extern void cpuset_read_unlock(void);
61 extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
62 extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);
63 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
64 #define cpuset_current_mems_allowed (current->mems_allowed)
65 void cpuset_init_current_mems_allowed(void);
66 int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
67 
68 extern bool __cpuset_node_allowed(int node, gfp_t gfp_mask);
69 
70 static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
71 {
72 	if (cpusets_enabled())
73 		return __cpuset_node_allowed(node, gfp_mask);
74 	return true;
75 }
76 
77 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
78 {
79 	return __cpuset_node_allowed(zone_to_nid(z), gfp_mask);
80 }
81 
82 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
83 {
84 	if (cpusets_enabled())
85 		return __cpuset_zone_allowed(z, gfp_mask);
86 	return true;
87 }
88 
89 extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
90 					  const struct task_struct *tsk2);
91 
92 #define cpuset_memory_pressure_bump() 				\
93 	do {							\
94 		if (cpuset_memory_pressure_enabled)		\
95 			__cpuset_memory_pressure_bump();	\
96 	} while (0)
97 extern int cpuset_memory_pressure_enabled;
98 extern void __cpuset_memory_pressure_bump(void);
99 
100 extern void cpuset_task_status_allowed(struct seq_file *m,
101 					struct task_struct *task);
102 extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
103 			    struct pid *pid, struct task_struct *tsk);
104 
105 extern int cpuset_mem_spread_node(void);
106 extern int cpuset_slab_spread_node(void);
107 
108 static inline int cpuset_do_page_mem_spread(void)
109 {
110 	return task_spread_page(current);
111 }
112 
113 static inline int cpuset_do_slab_mem_spread(void)
114 {
115 	return task_spread_slab(current);
116 }
117 
118 extern bool current_cpuset_is_being_rebound(void);
119 
120 extern void rebuild_sched_domains(void);
121 
122 extern void cpuset_print_current_mems_allowed(void);
123 
124 /*
125  * read_mems_allowed_begin is required when making decisions involving
126  * mems_allowed such as during page allocation. mems_allowed can be updated in
127  * parallel and depending on the new value an operation can fail potentially
128  * causing process failure. A retry loop with read_mems_allowed_begin and
129  * read_mems_allowed_retry prevents these artificial failures.
130  */
131 static inline unsigned int read_mems_allowed_begin(void)
132 {
133 	if (!static_branch_unlikely(&cpusets_pre_enable_key))
134 		return 0;
135 
136 	return read_seqcount_begin(&current->mems_allowed_seq);
137 }
138 
139 /*
140  * If this returns true, the operation that took place after
141  * read_mems_allowed_begin may have failed artificially due to a concurrent
142  * update of mems_allowed. It is up to the caller to retry the operation if
143  * appropriate.
144  */
145 static inline bool read_mems_allowed_retry(unsigned int seq)
146 {
147 	if (!static_branch_unlikely(&cpusets_enabled_key))
148 		return false;
149 
150 	return read_seqcount_retry(&current->mems_allowed_seq, seq);
151 }
152 
153 static inline void set_mems_allowed(nodemask_t nodemask)
154 {
155 	unsigned long flags;
156 
157 	task_lock(current);
158 	local_irq_save(flags);
159 	write_seqcount_begin(&current->mems_allowed_seq);
160 	current->mems_allowed = nodemask;
161 	write_seqcount_end(&current->mems_allowed_seq);
162 	local_irq_restore(flags);
163 	task_unlock(current);
164 }
165 
166 #else /* !CONFIG_CPUSETS */
167 
168 static inline bool cpusets_enabled(void) { return false; }
169 
170 static inline int cpuset_init(void) { return 0; }
171 static inline void cpuset_init_smp(void) {}
172 
173 static inline void cpuset_force_rebuild(void) { }
174 
175 static inline void cpuset_update_active_cpus(void)
176 {
177 	partition_sched_domains(1, NULL, NULL);
178 }
179 
180 static inline void cpuset_wait_for_hotplug(void) { }
181 
182 static inline void cpuset_read_lock(void) { }
183 static inline void cpuset_read_unlock(void) { }
184 
185 static inline void cpuset_cpus_allowed(struct task_struct *p,
186 				       struct cpumask *mask)
187 {
188 	cpumask_copy(mask, task_cpu_possible_mask(p));
189 }
190 
191 static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p)
192 {
193 	return false;
194 }
195 
196 static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
197 {
198 	return node_possible_map;
199 }
200 
201 #define cpuset_current_mems_allowed (node_states[N_MEMORY])
202 static inline void cpuset_init_current_mems_allowed(void) {}
203 
204 static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
205 {
206 	return 1;
207 }
208 
209 static inline bool cpuset_node_allowed(int node, 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 bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
220 {
221 	return true;
222 }
223 
224 static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
225 						 const struct task_struct *tsk2)
226 {
227 	return 1;
228 }
229 
230 static inline void cpuset_memory_pressure_bump(void) {}
231 
232 static inline void cpuset_task_status_allowed(struct seq_file *m,
233 						struct task_struct *task)
234 {
235 }
236 
237 static inline int cpuset_mem_spread_node(void)
238 {
239 	return 0;
240 }
241 
242 static inline int cpuset_slab_spread_node(void)
243 {
244 	return 0;
245 }
246 
247 static inline int cpuset_do_page_mem_spread(void)
248 {
249 	return 0;
250 }
251 
252 static inline int cpuset_do_slab_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 */
288