diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig | 3 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/bitmap.c | 2 | ||||
| -rw-r--r-- | lib/genalloc.c | 300 | ||||
| -rw-r--r-- | lib/llist.c | 129 |
5 files changed, 377 insertions, 59 deletions
diff --git a/lib/Kconfig b/lib/Kconfig index 32f3e5a..6c695ff 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -276,4 +276,7 @@ config CORDIC so its calculations are in fixed point. Modules can select this when they require this function. Module will be called cordic. +config LLIST + bool + endmenu diff --git a/lib/Makefile b/lib/Makefile index 892f4e2..6457af4a 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -115,6 +115,8 @@ obj-$(CONFIG_CPU_RMAP) += cpu_rmap.o obj-$(CONFIG_CORDIC) += cordic.o +obj-$(CONFIG_LLIST) += llist.o + hostprogs-y := gen_crc32table clean-files := crc32table.h diff --git a/lib/bitmap.c b/lib/bitmap.c index 37ef4b0..2f4412e 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -271,8 +271,6 @@ int __bitmap_weight(const unsigned long *bitmap, int bits) } EXPORT_SYMBOL(__bitmap_weight); -#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG)) - void bitmap_set(unsigned long *map, int start, int nr) { unsigned long *p = map + BIT_WORD(start); diff --git a/lib/genalloc.c b/lib/genalloc.c index 577ddf8..f352cc4 100644 --- a/lib/genalloc.c +++ b/lib/genalloc.c @@ -1,8 +1,26 @@ /* - * Basic general purpose allocator for managing special purpose memory - * not managed by the regular kmalloc/kfree interface. - * Uses for this includes on-device special memory, uncached memory - * etc. + * Basic general purpose allocator for managing special purpose + * memory, for example, memory that is not managed by the regular + * kmalloc/kfree interface. Uses for this includes on-device special + * memory, uncached memory etc. + * + * It is safe to use the allocator in NMI handlers and other special + * unblockable contexts that could otherwise deadlock on locks. This + * is implemented by using atomic operations and retries on any + * conflicts. The disadvantage is that there may be livelocks in + * extreme cases. For better scalability, one allocator can be used + * for each CPU. + * + * The lockless operation only works if there is enough memory + * available. If new memory is added to the pool a lock has to be + * still taken. So any user relying on locklessness has to ensure + * that sufficient memory is preallocated. + * + * The basic atomic operation of this allocator is cmpxchg on long. + * On architectures that don't have NMI-safe cmpxchg implementation, + * the allocator can NOT be used in NMI handler. So code uses the + * allocator in NMI handler should depend on + * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG. * * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org> * @@ -13,8 +31,109 @@ #include <linux/slab.h> #include <linux/module.h> #include <linux/bitmap.h> +#include <linux/rculist.h> +#include <linux/interrupt.h> #include <linux/genalloc.h> +static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set) +{ + unsigned long val, nval; + + nval = *addr; + do { + val = nval; + if (val & mask_to_set) + return -EBUSY; + cpu_relax(); + } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val); + + return 0; +} + +static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear) +{ + unsigned long val, nval; + + nval = *addr; + do { + val = nval; + if ((val & mask_to_clear) != mask_to_clear) + return -EBUSY; + cpu_relax(); + } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val); + + return 0; +} + +/* + * bitmap_set_ll - set the specified number of bits at the specified position + * @map: pointer to a bitmap + * @start: a bit position in @map + * @nr: number of bits to set + * + * Set @nr bits start from @start in @map lock-lessly. Several users + * can set/clear the same bitmap simultaneously without lock. If two + * users set the same bit, one user will return remain bits, otherwise + * return 0. + */ +static int bitmap_set_ll(unsigned long *map, int start, int nr) +{ + unsigned long *p = map + BIT_WORD(start); + const int size = start + nr; + int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG); + unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); + + while (nr - bits_to_set >= 0) { + if (set_bits_ll(p, mask_to_set)) + return nr; + nr -= bits_to_set; + bits_to_set = BITS_PER_LONG; + mask_to_set = ~0UL; + p++; + } + if (nr) { + mask_to_set &= BITMAP_LAST_WORD_MASK(size); + if (set_bits_ll(p, mask_to_set)) + return nr; + } + + return 0; +} + +/* + * bitmap_clear_ll - clear the specified number of bits at the specified position + * @map: pointer to a bitmap + * @start: a bit position in @map + * @nr: number of bits to set + * + * Clear @nr bits start from @start in @map lock-lessly. Several users + * can set/clear the same bitmap simultaneously without lock. If two + * users clear the same bit, one user will return remain bits, + * otherwise return 0. + */ +static int bitmap_clear_ll(unsigned long *map, int start, int nr) +{ + unsigned long *p = map + BIT_WORD(start); + const int size = start + nr; + int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); + unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); + + while (nr - bits_to_clear >= 0) { + if (clear_bits_ll(p, mask_to_clear)) + return nr; + nr -= bits_to_clear; + bits_to_clear = BITS_PER_LONG; + mask_to_clear = ~0UL; + p++; + } + if (nr) { + mask_to_clear &= BITMAP_LAST_WORD_MASK(size); + if (clear_bits_ll(p, mask_to_clear)) + return nr; + } + + return 0; +} /** * gen_pool_create - create a new special memory pool @@ -30,7 +149,7 @@ struct gen_pool *gen_pool_create(int min_alloc_order, int nid) pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid); if (pool != NULL) { - rwlock_init(&pool->lock); + spin_lock_init(&pool->lock); INIT_LIST_HEAD(&pool->chunks); pool->min_alloc_order = min_alloc_order; } @@ -63,14 +182,14 @@ int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phy if (unlikely(chunk == NULL)) return -ENOMEM; - spin_lock_init(&chunk->lock); chunk->phys_addr = phys; chunk->start_addr = virt; chunk->end_addr = virt + size; + atomic_set(&chunk->avail, size); - write_lock(&pool->lock); - list_add(&chunk->next_chunk, &pool->chunks); - write_unlock(&pool->lock); + spin_lock(&pool->lock); + list_add_rcu(&chunk->next_chunk, &pool->chunks); + spin_unlock(&pool->lock); return 0; } @@ -85,19 +204,19 @@ EXPORT_SYMBOL(gen_pool_add_virt); */ phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr) { - struct list_head *_chunk; struct gen_pool_chunk *chunk; + phys_addr_t paddr = -1; - read_lock(&pool->lock); - list_for_each(_chunk, &pool->chunks) { - chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); - - if (addr >= chunk->start_addr && addr < chunk->end_addr) - return chunk->phys_addr + addr - chunk->start_addr; + rcu_read_lock(); + list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) { + if (addr >= chunk->start_addr && addr < chunk->end_addr) { + paddr = chunk->phys_addr + (addr - chunk->start_addr); + break; + } } - read_unlock(&pool->lock); + rcu_read_unlock(); - return -1; + return paddr; } EXPORT_SYMBOL(gen_pool_virt_to_phys); @@ -115,7 +234,6 @@ void gen_pool_destroy(struct gen_pool *pool) int order = pool->min_alloc_order; int bit, end_bit; - list_for_each_safe(_chunk, _next_chunk, &pool->chunks) { chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); list_del(&chunk->next_chunk); @@ -137,44 +255,50 @@ EXPORT_SYMBOL(gen_pool_destroy); * @size: number of bytes to allocate from the pool * * Allocate the requested number of bytes from the specified pool. - * Uses a first-fit algorithm. + * Uses a first-fit algorithm. Can not be used in NMI handler on + * architectures without NMI-safe cmpxchg implementation. */ unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size) { - struct list_head *_chunk; struct gen_pool_chunk *chunk; - unsigned long addr, flags; + unsigned long addr = 0; int order = pool->min_alloc_order; - int nbits, start_bit, end_bit; + int nbits, start_bit = 0, end_bit, remain; + +#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG + BUG_ON(in_nmi()); +#endif if (size == 0) return 0; nbits = (size + (1UL << order) - 1) >> order; - - read_lock(&pool->lock); - list_for_each(_chunk, &pool->chunks) { - chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); + rcu_read_lock(); + list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) { + if (size > atomic_read(&chunk->avail)) + continue; end_bit = (chunk->end_addr - chunk->start_addr) >> order; - - spin_lock_irqsave(&chunk->lock, flags); - start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit, 0, - nbits, 0); - if (start_bit >= end_bit) { - spin_unlock_irqrestore(&chunk->lock, flags); +retry: + start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit, + start_bit, nbits, 0); + if (start_bit >= end_bit) continue; + remain = bitmap_set_ll(chunk->bits, start_bit, nbits); + if (remain) { + remain = bitmap_clear_ll(chunk->bits, start_bit, + nbits - remain); + BUG_ON(remain); + goto retry; } addr = chunk->start_addr + ((unsigned long)start_bit << order); - - bitmap_set(chunk->bits, start_bit, nbits); - spin_unlock_irqrestore(&chunk->lock, flags); - read_unlock(&pool->lock); - return addr; + size = nbits << order; + atomic_sub(size, &chunk->avail); + break; } - read_unlock(&pool->lock); - return 0; + rcu_read_unlock(); + return addr; } EXPORT_SYMBOL(gen_pool_alloc); @@ -184,33 +308,95 @@ EXPORT_SYMBOL(gen_pool_alloc); * @addr: starting address of memory to free back to pool * @size: size in bytes of memory to free * - * Free previously allocated special memory back to the specified pool. + * Free previously allocated special memory back to the specified + * pool. Can not be used in NMI handler on architectures without + * NMI-safe cmpxchg implementation. */ void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size) { - struct list_head *_chunk; struct gen_pool_chunk *chunk; - unsigned long flags; int order = pool->min_alloc_order; - int bit, nbits; + int start_bit, nbits, remain; - nbits = (size + (1UL << order) - 1) >> order; - - read_lock(&pool->lock); - list_for_each(_chunk, &pool->chunks) { - chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); +#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG + BUG_ON(in_nmi()); +#endif + nbits = (size + (1UL << order) - 1) >> order; + rcu_read_lock(); + list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) { if (addr >= chunk->start_addr && addr < chunk->end_addr) { BUG_ON(addr + size > chunk->end_addr); - spin_lock_irqsave(&chunk->lock, flags); - bit = (addr - chunk->start_addr) >> order; - while (nbits--) - __clear_bit(bit++, chunk->bits); - spin_unlock_irqrestore(&chunk->lock, flags); - break; + start_bit = (addr - chunk->start_addr) >> order; + remain = bitmap_clear_ll(chunk->bits, start_bit, nbits); + BUG_ON(remain); + size = nbits << order; + atomic_add(size, &chunk->avail); + rcu_read_unlock(); + return; } } - BUG_ON(nbits > 0); - read_unlock(&pool->lock); + rcu_read_unlock(); + BUG(); } EXPORT_SYMBOL(gen_pool_free); + +/** + * gen_pool_for_each_chunk - call func for every chunk of generic memory pool + * @pool: the generic memory pool + * @func: func to call + * @data: additional data used by @func + * + * Call @func for every chunk of generic memory pool. The @func is + * called with rcu_read_lock held. + */ +void gen_pool_for_each_chunk(struct gen_pool *pool, + void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data), + void *data) +{ + struct gen_pool_chunk *chunk; + + rcu_read_lock(); + list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) + func(pool, chunk, data); + rcu_read_unlock(); +} +EXPORT_SYMBOL(gen_pool_for_each_chunk); + +/** + * gen_pool_avail - get available free space of the pool + * @pool: pool to get available free space + * + * Return available free space of the specified pool. + */ +size_t gen_pool_avail(struct gen_pool *pool) +{ + struct gen_pool_chunk *chunk; + size_t avail = 0; + + rcu_read_lock(); + list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) + avail += atomic_read(&chunk->avail); + rcu_read_unlock(); + return avail; +} +EXPORT_SYMBOL_GPL(gen_pool_avail); + +/** + * gen_pool_size - get size in bytes of memory managed by the pool + * @pool: pool to get size + * + * Return size in bytes of memory managed by the pool. + */ +size_t gen_pool_size(struct gen_pool *pool) +{ + struct gen_pool_chunk *chunk; + size_t size = 0; + + rcu_read_lock(); + list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) + size += chunk->end_addr - chunk->start_addr; + rcu_read_unlock(); + return size; +} +EXPORT_SYMBOL_GPL(gen_pool_size); diff --git a/lib/llist.c b/lib/llist.c new file mode 100644 index 0000000..da44572 --- /dev/null +++ b/lib/llist.c @@ -0,0 +1,129 @@ +/* + * Lock-less NULL terminated single linked list + * + * The basic atomic operation of this list is cmpxchg on long. On + * architectures that don't have NMI-safe cmpxchg implementation, the + * list can NOT be used in NMI handler. So code uses the list in NMI + * handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG. + * + * Copyright 2010,2011 Intel Corp. + * Author: Huang Ying <ying.huang@intel.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License version + * 2 as published by the Free Software Foundation; + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/llist.h> + +#include <asm/system.h> + +/** + * llist_add - add a new entry + * @new: new entry to be added + * @head: the head for your lock-less list + */ +void llist_add(struct llist_node *new, struct llist_head *head) +{ + struct llist_node *entry, *old_entry; + +#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG + BUG_ON(in_nmi()); +#endif + + entry = head->first; + do { + old_entry = entry; + new->next = entry; + cpu_relax(); + } while ((entry = cmpxchg(&head->first, old_entry, new)) != old_entry); +} +EXPORT_SYMBOL_GPL(llist_add); + +/** + * llist_add_batch - add several linked entries in batch + * @new_first: first entry in batch to be added + * @new_last: last entry in batch to be added + * @head: the head for your lock-less list + */ +void llist_add_batch(struct llist_node *new_first, struct llist_node *new_last, + struct llist_head *head) +{ + struct llist_node *entry, *old_entry; + +#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG + BUG_ON(in_nmi()); +#endif + + entry = head->first; + do { + old_entry = entry; + new_last->next = entry; + cpu_relax(); + } while ((entry = cmpxchg(&head->first, old_entry, new_first)) != old_entry); +} +EXPORT_SYMBOL_GPL(llist_add_batch); + +/** + * llist_del_first - delete the first entry of lock-less list + * @head: the head for your lock-less list + * + * If list is empty, return NULL, otherwise, return the first entry + * deleted, this is the newest added one. + * + * Only one llist_del_first user can be used simultaneously with + * multiple llist_add users without lock. Because otherwise + * llist_del_first, llist_add, llist_add (or llist_del_all, llist_add, + * llist_add) sequence in another user may change @head->first->next, + * but keep @head->first. If multiple consumers are needed, please + * use llist_del_all or use lock between consumers. + */ +struct llist_node *llist_del_first(struct llist_head *head) +{ + struct llist_node *entry, *old_entry, *next; + +#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG + BUG_ON(in_nmi()); +#endif + + entry = head->first; + do { + if (entry == NULL) + return NULL; + old_entry = entry; + next = entry->next; + cpu_relax(); + } while ((entry = cmpxchg(&head->first, old_entry, next)) != old_entry); + + return entry; +} +EXPORT_SYMBOL_GPL(llist_del_first); + +/** + * llist_del_all - delete all entries from lock-less list + * @head: the head of lock-less list to delete all entries + * + * If list is empty, return NULL, otherwise, delete all entries and + * return the pointer to the first entry. The order of entries + * deleted is from the newest to the oldest added one. + */ +struct llist_node *llist_del_all(struct llist_head *head) +{ +#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG + BUG_ON(in_nmi()); +#endif + + return xchg(&head->first, NULL); +} +EXPORT_SYMBOL_GPL(llist_del_all); |
