From 929f97276bcf7f4a95272ed08a85339b98ba210d Mon Sep 17 00:00:00 2001 From: Dean Nelson Date: Fri, 23 Jun 2006 02:03:21 -0700 Subject: [PATCH] [PATCH] change gen_pool allocator to not touch managed memory Modify the gen_pool allocator (lib/genalloc.c) to utilize a bitmap scheme instead of the buddy scheme. The purpose of this change is to eliminate the touching of the actual memory being allocated. Since the change modifies the interface, a change to the uncached allocator (arch/ia64/kernel/uncached.c) is also required. Both Andrey Volkov and Jes Sorenson have expressed a desire that the gen_pool allocator not write to the memory being managed. See the following: http://marc.theaimsgroup.com/?l=linux-kernel&m=113518602713125&w=2 http://marc.theaimsgroup.com/?l=linux-kernel&m=113533568827916&w=2 Signed-off-by: Dean Nelson Cc: Andrey Volkov Acked-by: Jes Sorensen Cc: "Luck, Tony" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/ia64/kernel/uncached.c | 200 ++++++++++++----------- arch/ia64/sn/kernel/sn2/cache.c | 15 +- include/linux/genalloc.h | 75 ++++----- lib/genalloc.c | 351 +++++++++++++++++++--------------------- 4 files changed, 316 insertions(+), 325 deletions(-) rewrite include/linux/genalloc.h (65%) rewrite lib/genalloc.c (85%) diff --git a/arch/ia64/kernel/uncached.c b/arch/ia64/kernel/uncached.c index fcd2bad0286..5f03b9e524d 100644 --- a/arch/ia64/kernel/uncached.c +++ b/arch/ia64/kernel/uncached.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2001-2005 Silicon Graphics, Inc. All rights reserved. + * Copyright (C) 2001-2006 Silicon Graphics, Inc. All rights reserved. * * This program is free software; you can redistribute it and/or modify it * under the terms of version 2 of the GNU General Public License @@ -29,15 +29,8 @@ #include #include -#define DEBUG 0 -#if DEBUG -#define dprintk printk -#else -#define dprintk(x...) do { } while (0) -#endif - -void __init efi_memmap_walk_uc (efi_freemem_callback_t callback); +extern void __init efi_memmap_walk_uc(efi_freemem_callback_t, void *); #define MAX_UNCACHED_GRANULES 5 static int allocated_granules; @@ -60,6 +53,7 @@ static void uncached_ipi_visibility(void *data) static void uncached_ipi_mc_drain(void *data) { int status; + status = ia64_pal_mc_drain(); if (status) printk(KERN_WARNING "ia64_pal_mc_drain() failed with %i on " @@ -67,30 +61,35 @@ static void uncached_ipi_mc_drain(void *data) } -static unsigned long -uncached_get_new_chunk(struct gen_pool *poolp) +/* + * Add a new chunk of uncached memory pages to the specified pool. + * + * @pool: pool to add new chunk of uncached memory to + * @nid: node id of node to allocate memory from, or -1 + * + * This is accomplished by first allocating a granule of cached memory pages + * and then converting them to uncached memory pages. + */ +static int uncached_add_chunk(struct gen_pool *pool, int nid) { struct page *page; - void *tmp; int status, i; - unsigned long addr, node; + unsigned long c_addr, uc_addr; if (allocated_granules >= MAX_UNCACHED_GRANULES) - return 0; + return -1; + + /* attempt to allocate a granule's worth of cached memory pages */ - node = poolp->private; - page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, + page = alloc_pages_node(nid, GFP_KERNEL | __GFP_ZERO, IA64_GRANULE_SHIFT-PAGE_SHIFT); + if (!page) + return -1; - dprintk(KERN_INFO "get_new_chunk page %p, addr %lx\n", - page, (unsigned long)(page-vmem_map) << PAGE_SHIFT); + /* convert the memory pages from cached to uncached */ - /* - * Do magic if no mem on local node! XXX - */ - if (!page) - return 0; - tmp = page_address(page); + c_addr = (unsigned long)page_address(page); + uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET; /* * There's a small race here where it's possible for someone to @@ -100,76 +99,90 @@ uncached_get_new_chunk(struct gen_pool *poolp) for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++) SetPageUncached(&page[i]); - flush_tlb_kernel_range(tmp, tmp + IA64_GRANULE_SIZE); + flush_tlb_kernel_range(uc_addr, uc_adddr + IA64_GRANULE_SIZE); status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL); - - dprintk(KERN_INFO "pal_prefetch_visibility() returns %i on cpu %i\n", - status, raw_smp_processor_id()); - if (!status) { status = smp_call_function(uncached_ipi_visibility, NULL, 0, 1); if (status) - printk(KERN_WARNING "smp_call_function failed for " - "uncached_ipi_visibility! (%i)\n", status); + goto failed; } + preempt_disable(); + if (ia64_platform_is("sn2")) - sn_flush_all_caches((unsigned long)tmp, IA64_GRANULE_SIZE); + sn_flush_all_caches(uc_addr, IA64_GRANULE_SIZE); else - flush_icache_range((unsigned long)tmp, - (unsigned long)tmp+IA64_GRANULE_SIZE); + flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE); + + /* flush the just introduced uncached translation from the TLB */ + local_flush_tlb_all(); + + preempt_enable(); ia64_pal_mc_drain(); status = smp_call_function(uncached_ipi_mc_drain, NULL, 0, 1); if (status) - printk(KERN_WARNING "smp_call_function failed for " - "uncached_ipi_mc_drain! (%i)\n", status); + goto failed; - addr = (unsigned long)tmp - PAGE_OFFSET + __IA64_UNCACHED_OFFSET; + /* + * The chunk of memory pages has been converted to uncached so now we + * can add it to the pool. + */ + status = gen_pool_add(pool, uc_addr, IA64_GRANULE_SIZE, nid); + if (status) + goto failed; allocated_granules++; - return addr; + return 0; + + /* failed to convert or add the chunk so give it back to the kernel */ +failed: + for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++) + ClearPageUncached(&page[i]); + + free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT); + return -1; } /* * uncached_alloc_page * + * @starting_nid: node id of node to start with, or -1 + * * Allocate 1 uncached page. Allocates on the requested node. If no * uncached pages are available on the requested node, roundrobin starting - * with higher nodes. + * with the next higher node. */ -unsigned long -uncached_alloc_page(int nid) +unsigned long uncached_alloc_page(int starting_nid) { - unsigned long maddr; + unsigned long uc_addr; + struct gen_pool *pool; + int nid; - maddr = gen_pool_alloc(uncached_pool[nid], PAGE_SIZE); + if (unlikely(starting_nid >= MAX_NUMNODES)) + return 0; - dprintk(KERN_DEBUG "uncached_alloc_page returns %lx on node %i\n", - maddr, nid); + if (starting_nid < 0) + starting_nid = numa_node_id(); + nid = starting_nid; - /* - * If no memory is availble on our local node, try the - * remaining nodes in the system. - */ - if (!maddr) { - int i; - - for (i = MAX_NUMNODES - 1; i >= 0; i--) { - if (i == nid || !node_online(i)) - continue; - maddr = gen_pool_alloc(uncached_pool[i], PAGE_SIZE); - dprintk(KERN_DEBUG "uncached_alloc_page alternate search " - "returns %lx on node %i\n", maddr, i); - if (maddr) { - break; - } - } - } + do { + if (!node_online(nid)) + continue; + pool = uncached_pool[nid]; + if (pool == NULL) + continue; + do { + uc_addr = gen_pool_alloc(pool, PAGE_SIZE); + if (uc_addr != 0) + return uc_addr; + } while (uncached_add_chunk(pool, nid) == 0); + + } while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid); - return maddr; + return 0; } EXPORT_SYMBOL(uncached_alloc_page); @@ -177,21 +190,22 @@ EXPORT_SYMBOL(uncached_alloc_page); /* * uncached_free_page * + * @uc_addr: uncached address of page to free + * * Free a single uncached page. */ -void -uncached_free_page(unsigned long maddr) +void uncached_free_page(unsigned long uc_addr) { - int node; - - node = paddr_to_nid(maddr - __IA64_UNCACHED_OFFSET); + int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET); + struct gen_pool *pool = uncached_pool[nid]; - dprintk(KERN_DEBUG "uncached_free_page(%lx) on node %i\n", maddr, node); + if (unlikely(pool == NULL)) + return; - if ((maddr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET) - panic("uncached_free_page invalid address %lx\n", maddr); + if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET) + panic("uncached_free_page invalid address %lx\n", uc_addr); - gen_pool_free(uncached_pool[node], maddr, PAGE_SIZE); + gen_pool_free(pool, uc_addr, PAGE_SIZE); } EXPORT_SYMBOL(uncached_free_page); @@ -199,43 +213,39 @@ EXPORT_SYMBOL(uncached_free_page); /* * uncached_build_memmap, * + * @uc_start: uncached starting address of a chunk of uncached memory + * @uc_end: uncached ending address of a chunk of uncached memory + * @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc()) + * * Called at boot time to build a map of pages that can be used for * memory special operations. */ -static int __init -uncached_build_memmap(unsigned long start, unsigned long end, void *arg) +static int __init uncached_build_memmap(unsigned long uc_start, + unsigned long uc_end, void *arg) { - long length = end - start; - int node; - - dprintk(KERN_ERR "uncached_build_memmap(%lx %lx)\n", start, end); + int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET); + struct gen_pool *pool = uncached_pool[nid]; + size_t size = uc_end - uc_start; touch_softlockup_watchdog(); - memset((char *)start, 0, length); - node = paddr_to_nid(start - __IA64_UNCACHED_OFFSET); - - for (; start < end ; start += PAGE_SIZE) { - dprintk(KERN_INFO "sticking %lx into the pool!\n", start); - gen_pool_free(uncached_pool[node], start, PAGE_SIZE); + if (pool != NULL) { + memset((char *)uc_start, 0, size); + (void) gen_pool_add(pool, uc_start, size, nid); } - return 0; } -static int __init uncached_init(void) { - int i; +static int __init uncached_init(void) +{ + int nid; - for (i = 0; i < MAX_NUMNODES; i++) { - if (!node_online(i)) - continue; - uncached_pool[i] = gen_pool_create(0, IA64_GRANULE_SHIFT, - &uncached_get_new_chunk, i); + for_each_online_node(nid) { + uncached_pool[nid] = gen_pool_create(PAGE_SHIFT, nid); } - efi_memmap_walk_uc(uncached_build_memmap); - + efi_memmap_walk_uc(uncached_build_memmap, NULL); return 0; } diff --git a/arch/ia64/sn/kernel/sn2/cache.c b/arch/ia64/sn/kernel/sn2/cache.c index bc3cfa17cd0..2862cb33026 100644 --- a/arch/ia64/sn/kernel/sn2/cache.c +++ b/arch/ia64/sn/kernel/sn2/cache.c @@ -3,11 +3,12 @@ * License. See the file "COPYING" in the main directory of this archive * for more details. * - * Copyright (C) 2001-2003 Silicon Graphics, Inc. All rights reserved. + * Copyright (C) 2001-2003, 2006 Silicon Graphics, Inc. All rights reserved. * */ #include #include +#include /** * sn_flush_all_caches - flush a range of address from all caches (incl. L4) @@ -17,18 +18,24 @@ * Flush a range of addresses from all caches including L4. * All addresses fully or partially contained within * @flush_addr to @flush_addr + @bytes are flushed - * from the all caches. + * from all caches. */ void sn_flush_all_caches(long flush_addr, long bytes) { - flush_icache_range(flush_addr, flush_addr+bytes); + unsigned long addr = flush_addr; + + /* SHub1 requires a cached address */ + if (is_shub1() && (addr & RGN_BITS) == RGN_BASE(RGN_UNCACHED)) + addr = (addr - RGN_BASE(RGN_UNCACHED)) + RGN_BASE(RGN_KERNEL); + + flush_icache_range(addr, addr + bytes); /* * The last call may have returned before the caches * were actually flushed, so we call it again to make * sure. */ - flush_icache_range(flush_addr, flush_addr+bytes); + flush_icache_range(addr, addr + bytes); mb(); } EXPORT_SYMBOL(sn_flush_all_caches); diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h dissimilarity index 65% index 7fd0576a445..690c42803d2 100644 --- a/include/linux/genalloc.h +++ b/include/linux/genalloc.h @@ -1,40 +1,35 @@ -/* - * 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. - * - * This code is based on the buddy allocator found in the sym53c8xx_2 - * driver, adapted for general purpose use. - * - * This source code is licensed under the GNU General Public License, - * Version 2. See the file COPYING for more details. - */ - -#include - -#define ALLOC_MIN_SHIFT 5 /* 32 bytes minimum */ -/* - * Link between free memory chunks of a given size. - */ -struct gen_pool_link { - struct gen_pool_link *next; -}; - -/* - * Memory pool descriptor. - */ -struct gen_pool { - spinlock_t lock; - unsigned long (*get_new_chunk)(struct gen_pool *); - struct gen_pool *next; - struct gen_pool_link *h; - unsigned long private; - int max_chunk_shift; -}; - -unsigned long gen_pool_alloc(struct gen_pool *poolp, int size); -void gen_pool_free(struct gen_pool *mp, unsigned long ptr, int size); -struct gen_pool *gen_pool_create(int nr_chunks, int max_chunk_shift, - unsigned long (*fp)(struct gen_pool *), - unsigned long data); +/* + * 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. + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + + +/* + * General purpose special memory pool descriptor. + */ +struct gen_pool { + rwlock_t lock; + struct list_head chunks; /* list of chunks in this pool */ + int min_alloc_order; /* minimum allocation order */ +}; + +/* + * General purpose special memory pool chunk descriptor. + */ +struct gen_pool_chunk { + spinlock_t lock; + struct list_head next_chunk; /* next chunk in pool */ + unsigned long start_addr; /* starting address of memory chunk */ + unsigned long end_addr; /* ending address of memory chunk */ + unsigned long bits[0]; /* bitmap for allocating memory chunk */ +}; + +extern struct gen_pool *gen_pool_create(int, int); +extern int gen_pool_add(struct gen_pool *, unsigned long, size_t, int); +extern unsigned long gen_pool_alloc(struct gen_pool *, size_t); +extern void gen_pool_free(struct gen_pool *, unsigned long, size_t); diff --git a/lib/genalloc.c b/lib/genalloc.c dissimilarity index 85% index 9ce0a6a3b85..71338b48e88 100644 --- a/lib/genalloc.c +++ b/lib/genalloc.c @@ -1,186 +1,165 @@ -/* - * 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. - * - * This code is based on the buddy allocator found in the sym53c8xx_2 - * driver Copyright (C) 1999-2001 Gerard Roudier , - * and adapted for general purpose use. - * - * Copyright 2005 (C) Jes Sorensen - * - * This source code is licensed under the GNU General Public License, - * Version 2. See the file COPYING for more details. - */ - -#include -#include -#include -#include -#include -#include -#include -#include -#include - -#include - - -struct gen_pool *gen_pool_create(int nr_chunks, int max_chunk_shift, - unsigned long (*fp)(struct gen_pool *), - unsigned long data) -{ - struct gen_pool *poolp; - unsigned long tmp; - int i; - - /* - * This is really an arbitrary limit, +10 is enough for - * IA64_GRANULE_SHIFT, aka 16MB. If anyone needs a large limit - * this can be increased without problems. - */ - if ((max_chunk_shift > (PAGE_SHIFT + 10)) || - ((max_chunk_shift < ALLOC_MIN_SHIFT) && max_chunk_shift)) - return NULL; - - if (!max_chunk_shift) - max_chunk_shift = PAGE_SHIFT; - - poolp = kmalloc(sizeof(struct gen_pool), GFP_KERNEL); - if (!poolp) - return NULL; - memset(poolp, 0, sizeof(struct gen_pool)); - poolp->h = kmalloc(sizeof(struct gen_pool_link) * - (max_chunk_shift - ALLOC_MIN_SHIFT + 1), - GFP_KERNEL); - if (!poolp->h) { - printk(KERN_WARNING "gen_pool_alloc() failed to allocate\n"); - kfree(poolp); - return NULL; - } - memset(poolp->h, 0, sizeof(struct gen_pool_link) * - (max_chunk_shift - ALLOC_MIN_SHIFT + 1)); - - spin_lock_init(&poolp->lock); - poolp->get_new_chunk = fp; - poolp->max_chunk_shift = max_chunk_shift; - poolp->private = data; - - for (i = 0; i < nr_chunks; i++) { - tmp = poolp->get_new_chunk(poolp); - printk(KERN_INFO "allocated %lx\n", tmp); - if (!tmp) - break; - gen_pool_free(poolp, tmp, (1 << poolp->max_chunk_shift)); - } - - return poolp; -} -EXPORT_SYMBOL(gen_pool_create); - - -/* - * Simple power of two buddy-like generic allocator. - * Provides naturally aligned memory chunks. - */ -unsigned long gen_pool_alloc(struct gen_pool *poolp, int size) -{ - int j, i, s, max_chunk_size; - unsigned long a, flags; - struct gen_pool_link *h = poolp->h; - - max_chunk_size = 1 << poolp->max_chunk_shift; - - if (size > max_chunk_size) - return 0; - - size = max(size, 1 << ALLOC_MIN_SHIFT); - i = fls(size - 1); - s = 1 << i; - j = i -= ALLOC_MIN_SHIFT; - - spin_lock_irqsave(&poolp->lock, flags); - while (!h[j].next) { - if (s == max_chunk_size) { - struct gen_pool_link *ptr; - spin_unlock_irqrestore(&poolp->lock, flags); - ptr = (struct gen_pool_link *)poolp->get_new_chunk(poolp); - spin_lock_irqsave(&poolp->lock, flags); - h[j].next = ptr; - if (h[j].next) - h[j].next->next = NULL; - break; - } - j++; - s <<= 1; - } - a = (unsigned long) h[j].next; - if (a) { - h[j].next = h[j].next->next; - /* - * This should be split into a seperate function doing - * the chunk split in order to support custom - * handling memory not physically accessible by host - */ - while (j > i) { - j -= 1; - s >>= 1; - h[j].next = (struct gen_pool_link *) (a + s); - h[j].next->next = NULL; - } - } - spin_unlock_irqrestore(&poolp->lock, flags); - return a; -} -EXPORT_SYMBOL(gen_pool_alloc); - - -/* - * Counter-part of the generic allocator. - */ -void gen_pool_free(struct gen_pool *poolp, unsigned long ptr, int size) -{ - struct gen_pool_link *q; - struct gen_pool_link *h = poolp->h; - unsigned long a, b, flags; - int i, s, max_chunk_size; - - max_chunk_size = 1 << poolp->max_chunk_shift; - - if (size > max_chunk_size) - return; - - size = max(size, 1 << ALLOC_MIN_SHIFT); - i = fls(size - 1); - s = 1 << i; - i -= ALLOC_MIN_SHIFT; - - a = ptr; - - spin_lock_irqsave(&poolp->lock, flags); - while (1) { - if (s == max_chunk_size) { - ((struct gen_pool_link *)a)->next = h[i].next; - h[i].next = (struct gen_pool_link *)a; - break; - } - b = a ^ s; - q = &h[i]; - - while (q->next && q->next != (struct gen_pool_link *)b) - q = q->next; - - if (!q->next) { - ((struct gen_pool_link *)a)->next = h[i].next; - h[i].next = (struct gen_pool_link *)a; - break; - } - q->next = q->next->next; - a = a & b; - s <<= 1; - i++; - } - spin_unlock_irqrestore(&poolp->lock, flags); -} -EXPORT_SYMBOL(gen_pool_free); +/* + * 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. + * + * Copyright 2005 (C) Jes Sorensen + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + +#include +#include + + +/* + * Create a new special memory pool. + * + * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents + * @nid: node id of the node the pool structure should be allocated on, or -1 + */ +struct gen_pool *gen_pool_create(int min_alloc_order, int nid) +{ + struct gen_pool *pool; + + pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid); + if (pool != NULL) { + rwlock_init(&pool->lock); + INIT_LIST_HEAD(&pool->chunks); + pool->min_alloc_order = min_alloc_order; + } + return pool; +} +EXPORT_SYMBOL(gen_pool_create); + + +/* + * Add a new chunk of memory to the specified pool. + * + * @pool: pool to add new memory chunk to + * @addr: starting address of memory chunk to add to pool + * @size: size in bytes of the memory chunk to add to pool + * @nid: node id of the node the chunk structure and bitmap should be + * allocated on, or -1 + */ +int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size, + int nid) +{ + struct gen_pool_chunk *chunk; + int nbits = size >> pool->min_alloc_order; + int nbytes = sizeof(struct gen_pool_chunk) + + (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE; + + chunk = kmalloc_node(nbytes, GFP_KERNEL, nid); + if (unlikely(chunk == NULL)) + return -1; + + memset(chunk, 0, nbytes); + spin_lock_init(&chunk->lock); + chunk->start_addr = addr; + chunk->end_addr = addr + size; + + write_lock(&pool->lock); + list_add(&chunk->next_chunk, &pool->chunks); + write_unlock(&pool->lock); + + return 0; +} +EXPORT_SYMBOL(gen_pool_add); + + +/* + * Allocate the requested number of bytes from the specified pool. + * Uses a first-fit algorithm. + * + * @pool: pool to allocate from + * @size: number of bytes to allocate from the pool + */ +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; + int order = pool->min_alloc_order; + int nbits, bit, start_bit, end_bit; + + 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); + + end_bit = (chunk->end_addr - chunk->start_addr) >> order; + end_bit -= nbits + 1; + + spin_lock_irqsave(&chunk->lock, flags); + bit = -1; + while (bit + 1 < end_bit) { + bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1); + if (bit >= end_bit) + break; + + start_bit = bit; + if (nbits > 1) { + bit = find_next_bit(chunk->bits, bit + nbits, + bit + 1); + if (bit - start_bit < nbits) + continue; + } + + addr = chunk->start_addr + + ((unsigned long)start_bit << order); + while (nbits--) + __set_bit(start_bit++, &chunk->bits); + spin_unlock_irqrestore(&chunk->lock, flags); + read_unlock(&pool->lock); + return addr; + } + spin_unlock_irqrestore(&chunk->lock, flags); + } + read_unlock(&pool->lock); + return 0; +} +EXPORT_SYMBOL(gen_pool_alloc); + + +/* + * Free the specified memory back to the specified pool. + * + * @pool: pool to free to + * @addr: starting address of memory to free back to pool + * @size: size in bytes of memory to free + */ +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; + + 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); + + 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; + } + } + BUG_ON(nbits > 0); + read_unlock(&pool->lock); +} +EXPORT_SYMBOL(gen_pool_free); -- 2.11.4.GIT