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Linux/lib/cpumask.c

  1 #include <linux/slab.h>
  2 #include <linux/kernel.h>
  3 #include <linux/bitops.h>
  4 #include <linux/cpumask.h>
  5 #include <linux/export.h>
  6 #include <linux/bootmem.h>
  7 
  8 /**
  9  * cpumask_next_and - get the next cpu in *src1p & *src2p
 10  * @n: the cpu prior to the place to search (ie. return will be > @n)
 11  * @src1p: the first cpumask pointer
 12  * @src2p: the second cpumask pointer
 13  *
 14  * Returns >= nr_cpu_ids if no further cpus set in both.
 15  */
 16 int cpumask_next_and(int n, const struct cpumask *src1p,
 17                      const struct cpumask *src2p)
 18 {
 19         while ((n = cpumask_next(n, src1p)) < nr_cpu_ids)
 20                 if (cpumask_test_cpu(n, src2p))
 21                         break;
 22         return n;
 23 }
 24 EXPORT_SYMBOL(cpumask_next_and);
 25 
 26 /**
 27  * cpumask_any_but - return a "random" in a cpumask, but not this one.
 28  * @mask: the cpumask to search
 29  * @cpu: the cpu to ignore.
 30  *
 31  * Often used to find any cpu but smp_processor_id() in a mask.
 32  * Returns >= nr_cpu_ids if no cpus set.
 33  */
 34 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
 35 {
 36         unsigned int i;
 37 
 38         cpumask_check(cpu);
 39         for_each_cpu(i, mask)
 40                 if (i != cpu)
 41                         break;
 42         return i;
 43 }
 44 EXPORT_SYMBOL(cpumask_any_but);
 45 
 46 /* These are not inline because of header tangles. */
 47 #ifdef CONFIG_CPUMASK_OFFSTACK
 48 /**
 49  * alloc_cpumask_var_node - allocate a struct cpumask on a given node
 50  * @mask: pointer to cpumask_var_t where the cpumask is returned
 51  * @flags: GFP_ flags
 52  *
 53  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 54  * a nop returning a constant 1 (in <linux/cpumask.h>)
 55  * Returns TRUE if memory allocation succeeded, FALSE otherwise.
 56  *
 57  * In addition, mask will be NULL if this fails.  Note that gcc is
 58  * usually smart enough to know that mask can never be NULL if
 59  * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
 60  * too.
 61  */
 62 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
 63 {
 64         *mask = kmalloc_node(cpumask_size(), flags, node);
 65 
 66 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
 67         if (!*mask) {
 68                 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
 69                 dump_stack();
 70         }
 71 #endif
 72 
 73         return *mask != NULL;
 74 }
 75 EXPORT_SYMBOL(alloc_cpumask_var_node);
 76 
 77 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
 78 {
 79         return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
 80 }
 81 EXPORT_SYMBOL(zalloc_cpumask_var_node);
 82 
 83 /**
 84  * alloc_cpumask_var - allocate a struct cpumask
 85  * @mask: pointer to cpumask_var_t where the cpumask is returned
 86  * @flags: GFP_ flags
 87  *
 88  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 89  * a nop returning a constant 1 (in <linux/cpumask.h>).
 90  *
 91  * See alloc_cpumask_var_node.
 92  */
 93 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 94 {
 95         return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
 96 }
 97 EXPORT_SYMBOL(alloc_cpumask_var);
 98 
 99 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
100 {
101         return alloc_cpumask_var(mask, flags | __GFP_ZERO);
102 }
103 EXPORT_SYMBOL(zalloc_cpumask_var);
104 
105 /**
106  * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
107  * @mask: pointer to cpumask_var_t where the cpumask is returned
108  *
109  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
110  * a nop (in <linux/cpumask.h>).
111  * Either returns an allocated (zero-filled) cpumask, or causes the
112  * system to panic.
113  */
114 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
115 {
116         *mask = memblock_virt_alloc(cpumask_size(), 0);
117 }
118 
119 /**
120  * free_cpumask_var - frees memory allocated for a struct cpumask.
121  * @mask: cpumask to free
122  *
123  * This is safe on a NULL mask.
124  */
125 void free_cpumask_var(cpumask_var_t mask)
126 {
127         kfree(mask);
128 }
129 EXPORT_SYMBOL(free_cpumask_var);
130 
131 /**
132  * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
133  * @mask: cpumask to free
134  */
135 void __init free_bootmem_cpumask_var(cpumask_var_t mask)
136 {
137         memblock_free_early(__pa(mask), cpumask_size());
138 }
139 #endif
140 
141 /**
142  * cpumask_local_spread - select the i'th cpu with local numa cpu's first
143  * @i: index number
144  * @node: local numa_node
145  *
146  * This function selects an online CPU according to a numa aware policy;
147  * local cpus are returned first, followed by non-local ones, then it
148  * wraps around.
149  *
150  * It's not very efficient, but useful for setup.
151  */
152 unsigned int cpumask_local_spread(unsigned int i, int node)
153 {
154         int cpu;
155 
156         /* Wrap: we always want a cpu. */
157         i %= num_online_cpus();
158 
159         if (node == -1) {
160                 for_each_cpu(cpu, cpu_online_mask)
161                         if (i-- == 0)
162                                 return cpu;
163         } else {
164                 /* NUMA first. */
165                 for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
166                         if (i-- == 0)
167                                 return cpu;
168 
169                 for_each_cpu(cpu, cpu_online_mask) {
170                         /* Skip NUMA nodes, done above. */
171                         if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
172                                 continue;
173 
174                         if (i-- == 0)
175                                 return cpu;
176                 }
177         }
178         BUG();
179 }
180 EXPORT_SYMBOL(cpumask_local_spread);
181 

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