xref: /linux-6.15/include/linux/cpuset.h (revision be040bea) 
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 void cpuset_inc(void)
41 {
42 	static_branch_inc(&cpusets_pre_enable_key);
43 	static_branch_inc(&cpusets_enabled_key);
44 }
45 
46 static inline void cpuset_dec(void)
47 {
48 	static_branch_dec(&cpusets_enabled_key);
49 	static_branch_dec(&cpusets_pre_enable_key);
50 }
51 
52 extern int cpuset_init(void);
53 extern void cpuset_init_smp(void);
54 extern void cpuset_update_active_cpus(void);
55 extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
56 extern void cpuset_cpus_allowed_fallback(struct task_struct *p);
57 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
58 #define cpuset_current_mems_allowed (current->mems_allowed)
59 void cpuset_init_current_mems_allowed(void);
60 int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
61 
62 extern bool __cpuset_node_allowed(int node, gfp_t gfp_mask);
63 
64 static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
65 {
66 	if (cpusets_enabled())
67 		return __cpuset_node_allowed(node, gfp_mask);
68 	return true;
69 }
70 
71 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
72 {
73 	return __cpuset_node_allowed(zone_to_nid(z), gfp_mask);
74 }
75 
76 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
77 {
78 	if (cpusets_enabled())
79 		return __cpuset_zone_allowed(z, gfp_mask);
80 	return true;
81 }
82 
83 extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
84 					  const struct task_struct *tsk2);
85 
86 #define cpuset_memory_pressure_bump() 				\
87 	do {							\
88 		if (cpuset_memory_pressure_enabled)		\
89 			__cpuset_memory_pressure_bump();	\
90 	} while (0)
91 extern int cpuset_memory_pressure_enabled;
92 extern void __cpuset_memory_pressure_bump(void);
93 
94 extern void cpuset_task_status_allowed(struct seq_file *m,
95 					struct task_struct *task);
96 extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
97 			    struct pid *pid, struct task_struct *tsk);
98 
99 extern int cpuset_mem_spread_node(void);
100 extern int cpuset_slab_spread_node(void);
101 
102 static inline int cpuset_do_page_mem_spread(void)
103 {
104 	return task_spread_page(current);
105 }
106 
107 static inline int cpuset_do_slab_mem_spread(void)
108 {
109 	return task_spread_slab(current);
110 }
111 
112 extern int current_cpuset_is_being_rebound(void);
113 
114 extern void rebuild_sched_domains(void);
115 
116 extern void cpuset_print_current_mems_allowed(void);
117 
118 /*
119  * read_mems_allowed_begin is required when making decisions involving
120  * mems_allowed such as during page allocation. mems_allowed can be updated in
121  * parallel and depending on the new value an operation can fail potentially
122  * causing process failure. A retry loop with read_mems_allowed_begin and
123  * read_mems_allowed_retry prevents these artificial failures.
124  */
125 static inline unsigned int read_mems_allowed_begin(void)
126 {
127 	if (!static_branch_unlikely(&cpusets_pre_enable_key))
128 		return 0;
129 
130 	return read_seqcount_begin(&current->mems_allowed_seq);
131 }
132 
133 /*
134  * If this returns true, the operation that took place after
135  * read_mems_allowed_begin may have failed artificially due to a concurrent
136  * update of mems_allowed. It is up to the caller to retry the operation if
137  * appropriate.
138  */
139 static inline bool read_mems_allowed_retry(unsigned int seq)
140 {
141 	if (!static_branch_unlikely(&cpusets_enabled_key))
142 		return false;
143 
144 	return read_seqcount_retry(&current->mems_allowed_seq, seq);
145 }
146 
147 static inline void set_mems_allowed(nodemask_t nodemask)
148 {
149 	unsigned long flags;
150 
151 	task_lock(current);
152 	local_irq_save(flags);
153 	write_seqcount_begin(&current->mems_allowed_seq);
154 	current->mems_allowed = nodemask;
155 	write_seqcount_end(&current->mems_allowed_seq);
156 	local_irq_restore(flags);
157 	task_unlock(current);
158 }
159 
160 #else /* !CONFIG_CPUSETS */
161 
162 static inline bool cpusets_enabled(void) { return false; }
163 
164 static inline int cpuset_init(void) { return 0; }
165 static inline void cpuset_init_smp(void) {}
166 
167 static inline void cpuset_update_active_cpus(void)
168 {
169 	partition_sched_domains(1, NULL, NULL);
170 }
171 
172 static inline void cpuset_cpus_allowed(struct task_struct *p,
173 				       struct cpumask *mask)
174 {
175 	cpumask_copy(mask, cpu_possible_mask);
176 }
177 
178 static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
179 {
180 }
181 
182 static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
183 {
184 	return node_possible_map;
185 }
186 
187 #define cpuset_current_mems_allowed (node_states[N_MEMORY])
188 static inline void cpuset_init_current_mems_allowed(void) {}
189 
190 static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
191 {
192 	return 1;
193 }
194 
195 static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
196 {
197 	return true;
198 }
199 
200 static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
201 {
202 	return true;
203 }
204 
205 static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
206 {
207 	return true;
208 }
209 
210 static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
211 						 const struct task_struct *tsk2)
212 {
213 	return 1;
214 }
215 
216 static inline void cpuset_memory_pressure_bump(void) {}
217 
218 static inline void cpuset_task_status_allowed(struct seq_file *m,
219 						struct task_struct *task)
220 {
221 }
222 
223 static inline int cpuset_mem_spread_node(void)
224 {
225 	return 0;
226 }
227 
228 static inline int cpuset_slab_spread_node(void)
229 {
230 	return 0;
231 }
232 
233 static inline int cpuset_do_page_mem_spread(void)
234 {
235 	return 0;
236 }
237 
238 static inline int cpuset_do_slab_mem_spread(void)
239 {
240 	return 0;
241 }
242 
243 static inline int current_cpuset_is_being_rebound(void)
244 {
245 	return 0;
246 }
247 
248 static inline void rebuild_sched_domains(void)
249 {
250 	partition_sched_domains(1, NULL, NULL);
251 }
252 
253 static inline void cpuset_print_current_mems_allowed(void)
254 {
255 }
256 
257 static inline void set_mems_allowed(nodemask_t nodemask)
258 {
259 }
260 
261 static inline unsigned int read_mems_allowed_begin(void)
262 {
263 	return 0;
264 }
265 
266 static inline bool read_mems_allowed_retry(unsigned int seq)
267 {
268 	return false;
269 }
270 
271 #endif /* !CONFIG_CPUSETS */
272 
273 #endif /* _LINUX_CPUSET_H */
274