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https://github.com/torvalds/linux
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92f36cca57
Add two new library functions: alloc_bucket_spinlocks and free_bucket_spinlocks. These are used to allocate and free an array of spinlocks that are useful as locks for hash buckets. The interface specifies the maximum number of spinlocks in the array as well as a CPU multiplier to derive the number of spinlocks to allocate. The number allocated is rounded up to a power of two to make the array amenable to hash lookup. Signed-off-by: Tom Herbert <tom@quantonium.net> Signed-off-by: David S. Miller <davem@davemloft.net>
54 lines
1.4 KiB
C
54 lines
1.4 KiB
C
#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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/* Allocate an array of spinlocks to be accessed by a hash. Two arguments
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* indicate the number of elements to allocate in the array. max_size
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* gives the maximum number of elements to allocate. cpu_mult gives
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* the number of locks per CPU to allocate. The size is rounded up
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* to a power of 2 to be suitable as a hash table.
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*/
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int alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *locks_mask,
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size_t max_size, unsigned int cpu_mult, gfp_t gfp)
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{
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spinlock_t *tlocks = NULL;
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unsigned int i, size;
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#if defined(CONFIG_PROVE_LOCKING)
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unsigned int nr_pcpus = 2;
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#else
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unsigned int nr_pcpus = num_possible_cpus();
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#endif
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if (cpu_mult) {
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nr_pcpus = min_t(unsigned int, nr_pcpus, 64UL);
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size = min_t(unsigned int, nr_pcpus * cpu_mult, max_size);
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} else {
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size = max_size;
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}
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if (sizeof(spinlock_t) != 0) {
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if (gfpflags_allow_blocking(gfp))
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tlocks = kvmalloc(size * sizeof(spinlock_t), gfp);
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else
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tlocks = kmalloc_array(size, sizeof(spinlock_t), gfp);
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if (!tlocks)
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return -ENOMEM;
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for (i = 0; i < size; i++)
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spin_lock_init(&tlocks[i]);
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}
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*locks = tlocks;
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*locks_mask = size - 1;
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return 0;
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}
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EXPORT_SYMBOL(alloc_bucket_spinlocks);
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void free_bucket_spinlocks(spinlock_t *locks)
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{
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kvfree(locks);
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}
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EXPORT_SYMBOL(free_bucket_spinlocks);
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