[PATCHv4,11/12] dmapool: link blocks across pages

Message ID	20230126215125.4069751-12-kbusch@meta.com (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> From: Keith Busch <kbusch@meta.com> To: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>, <willy@infradead.org>, <hch@lst.de>, <tonyb@cybernetics.com>, <akpm@linux-foundation.org> CC: <kernel-team@meta.com>, Keith Busch <kbusch@kernel.org> Subject: [PATCHv4 11/12] dmapool: link blocks across pages Date: Thu, 26 Jan 2023 13:51:24 -0800 Message-ID: <20230126215125.4069751-12-kbusch@meta.com> In-Reply-To: <20230126215125.4069751-1-kbusch@meta.com> References: <20230126215125.4069751-1-kbusch@meta.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	dmapool enhancements \| expand [PATCHv4,00/12] dmapool enhancements [PATCHv4,01/12] dmapool: add alloc/free performance test [PATCHv4,02/12] dmapool: remove checks for dev == NULL [PATCHv4,03/12] dmapool: use sysfs_emit() instead of scnprintf() [PATCHv4,04/12] dmapool: cleanup integer types [PATCHv4,05/12] dmapool: speedup DMAPOOL_DEBUG with init_on_alloc [PATCHv4,06/12] dmapool: move debug code to own functions [PATCHv4,07/12] dmapool: rearrange page alloc failure handling [PATCHv4,08/12] dmapool: consolidate page initialization [PATCHv4,09/12] dmapool: simplify freeing [PATCHv4,10/12] dmapool: don't memset on free twice [PATCHv4,11/12] dmapool: link blocks across pages [PATCHv4,12/12] dmapool: create/destroy cleanup

diff --git a/mm/dmapool.c b/mm/dmapool.c index 21e6d362c7264..bb8893b4f4b96 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -15,7 +15,7 @@ * represented by the 'struct dma_pool' which keeps a doubly-linked list of * allocated pages. Each page in the page_list is split into blocks of at * least 'size' bytes. Free blocks are tracked in an unsorted singly-linked - * list of free blocks within the page. Used blocks aren't tracked, but we + * list of free blocks across all pages. Used blocks aren't tracked, but we * keep a count of how many are currently allocated from each page. */ @@ -40,9 +40,18 @@ #define DMAPOOL_DEBUG 1 #endif +struct dma_block { + struct dma_block *next_block; + dma_addr_t dma; +}; + struct dma_pool { /* the pool */ struct list_head page_list; spinlock_t lock; + struct dma_block *next_block; + size_t nr_blocks; + size_t nr_active; + size_t nr_pages; struct device *dev; unsigned int size; unsigned int allocation; @@ -55,8 +64,6 @@ struct dma_page { /* cacheable header for 'allocation' bytes */ struct list_head page_list; void *vaddr; dma_addr_t dma; - unsigned int in_use; - unsigned int offset; }; static DEFINE_MUTEX(pools_lock); @@ -64,30 +71,18 @@ static DEFINE_MUTEX(pools_reg_lock); static ssize_t pools_show(struct device *dev, struct device_attribute *attr, char *buf) { - int size; - struct dma_page *page; struct dma_pool *pool; + unsigned size; size = sysfs_emit(buf, "poolinfo - 0.1\n"); mutex_lock(&pools_lock); list_for_each_entry(pool, &dev->dma_pools, pools) { - unsigned pages = 0; - size_t blocks = 0; - - spin_lock_irq(&pool->lock); - list_for_each_entry(page, &pool->page_list, page_list) { - pages++; - blocks += page->in_use; - } - spin_unlock_irq(&pool->lock); - /* per-pool info, no real statistics yet */ - size += sysfs_emit_at(buf, size, "%-16s %4zu %4zu %4u %2u\n", - pool->name, blocks, - (size_t) pages * - (pool->allocation / pool->size), - pool->size, pages); + size += sysfs_emit_at(buf, size, "%-16s %4zu %4zu %4u %2zu\n", + pool->name, pool->nr_active, + pool->nr_blocks, pool->size, + pool->nr_pages); } mutex_unlock(&pools_lock); @@ -97,17 +92,17 @@ static ssize_t pools_show(struct device *dev, struct device_attribute *attr, cha static DEVICE_ATTR_RO(pools); #ifdef DMAPOOL_DEBUG -static void pool_check_block(struct dma_pool *pool, void *retval, - unsigned int offset, gfp_t mem_flags) +static void pool_check_block(struct dma_pool *pool, struct dma_block *block, + gfp_t mem_flags) { + u8 *data = (void *)block; int i; - u8 *data = retval; - /* page->offset is stored in first 4 bytes */ - for (i = sizeof(offset); i < pool->size; i++) { + + for (i = sizeof(struct dma_block); i < pool->size; i++) { if (data[i] == POOL_POISON_FREED) continue; - dev_err(pool->dev, "%s %s, %p (corrupted)\n", - __func__, pool->name, retval); + dev_err(pool->dev, "%s %s, %p (corrupted)\n", __func__, + pool->name, block); /* * Dump the first 4 bytes even if they are not @@ -117,31 +112,46 @@ static void pool_check_block(struct dma_pool *pool, void *retval, data, pool->size, 1); break; } + if (!want_init_on_alloc(mem_flags)) - memset(retval, POOL_POISON_ALLOCATED, pool->size); + memset(block, POOL_POISON_ALLOCATED, pool->size); +} + +static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) +{ + struct dma_page *page; + + list_for_each_entry(page, &pool->page_list, page_list) { + if (dma < page->dma) + continue; + if ((dma - page->dma) < pool->allocation) + return page; + } + return NULL; } -static bool pool_page_err(struct dma_pool *pool, struct dma_page *page, - void *vaddr, dma_addr_t dma) +static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma) { - unsigned int offset = vaddr - page->vaddr; - unsigned int chain = page->offset; + struct dma_block *block = pool->next_block; + struct dma_page *page; - if ((dma - page->dma) != offset) { - dev_err(pool->dev, "%s %s, %p (bad vaddr)/%pad\n", + page = pool_find_page(pool, dma); + if (!page) { + dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n", __func__, pool->name, vaddr, &dma); return true; } - while (chain < pool->allocation) { - if (chain != offset) { - chain = *(int *)(page->vaddr + chain); + while (block) { + if (block != vaddr) { + block = block->next_block; continue; } dev_err(pool->dev, "%s %s, dma %pad already free\n", __func__, pool->name, &dma); return true; } + memset(vaddr, POOL_POISON_FREED, pool->size); return false; } @@ -151,14 +161,12 @@ static void pool_init_page(struct dma_pool *pool, struct dma_page *page) memset(page->vaddr, POOL_POISON_FREED, pool->allocation); } #else -static void pool_check_block(struct dma_pool *pool, void *retval, - unsigned int offset, gfp_t mem_flags) - +static void pool_check_block(struct dma_pool *pool, struct dma_block *block, + gfp_t mem_flags) { } -static bool pool_page_err(struct dma_pool *pool, struct dma_page *page, - void *vaddr, dma_addr_t dma) +static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma) { if (want_init_on_free()) memset(vaddr, 0, pool->size); @@ -170,6 +178,26 @@ static void pool_init_page(struct dma_pool *pool, struct dma_page *page) } #endif +static struct dma_block *pool_block_pop(struct dma_pool *pool) +{ + struct dma_block *block = pool->next_block; + + if (block) { + pool->next_block = block->next_block; + pool->nr_active++; + } + return block; +} + +static void pool_block_push(struct dma_pool *pool, struct dma_block *block, + dma_addr_t dma) +{ + block->dma = dma; + block->next_block = pool->next_block; + pool->next_block = block; +} + + /** * dma_pool_create - Creates a pool of consistent memory blocks, for dma. * @name: name of pool, for diagnostics @@ -210,8 +238,8 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, if (size == 0 || size > INT_MAX) return NULL; - else if (size < 4) - size = 4; + if (size < sizeof(struct dma_block)) + size = sizeof(struct dma_block); size = ALIGN(size, align); allocation = max_t(size_t, size, PAGE_SIZE); @@ -223,7 +251,7 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, boundary = min(boundary, allocation); - retval = kmalloc(sizeof(*retval), GFP_KERNEL); + retval = kzalloc(sizeof(*retval), GFP_KERNEL); if (!retval) return retval; @@ -236,7 +264,6 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, retval->size = size; retval->boundary = boundary; retval->allocation = allocation; - INIT_LIST_HEAD(&retval->pools); /* @@ -273,21 +300,25 @@ EXPORT_SYMBOL(dma_pool_create); static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) { - unsigned int offset = 0; - unsigned int next_boundary = pool->boundary; + unsigned int next_boundary = pool->boundary, offset = 0; + struct dma_block *block; pool_init_page(pool, page); - page->in_use = 0; - page->offset = 0; - do { - unsigned int next = offset + pool->size; - if (unlikely((next + pool->size) >= next_boundary)) { - next = next_boundary; + while (offset + pool->size <= pool->allocation) { + if (offset + pool->size > next_boundary) { + offset = next_boundary; next_boundary += pool->boundary; + continue; } - *(int *)(page->vaddr + offset) = next; - offset = next; - } while (offset < pool->allocation); + + block = page->vaddr + offset; + pool_block_push(pool, block, page->dma + offset); + offset += pool->size; + pool->nr_blocks++; + } + + list_add(&page->page_list, &pool->page_list); + pool->nr_pages++; } static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags) @@ -305,15 +336,9 @@ static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags) return NULL; } - pool_initialise_page(pool, page); return page; } -static inline bool is_page_busy(struct dma_page *page) -{ - return page->in_use != 0; -} - /** * dma_pool_destroy - destroys a pool of dma memory blocks. * @pool: dma pool that will be destroyed @@ -325,7 +350,7 @@ static inline bool is_page_busy(struct dma_page *page) void dma_pool_destroy(struct dma_pool *pool) { struct dma_page *page, *tmp; - bool empty = false; + bool empty = false, busy = false; if (unlikely(!pool)) return; @@ -340,13 +365,15 @@ void dma_pool_destroy(struct dma_pool *pool) device_remove_file(pool->dev, &dev_attr_pools); mutex_unlock(&pools_reg_lock); + if (pool->nr_active) { + dev_err(pool->dev, "%s %s busy\n", __func__, pool->name); + busy = true; + } + list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) { - if (!is_page_busy(page)) + if (!busy) dma_free_coherent(pool->dev, pool->allocation, page->vaddr, page->dma); - else - dev_err(pool->dev, "%s %s, %p busy\n", __func__, - pool->name, page->vaddr); list_del(&page->page_list); kfree(page); } @@ -368,58 +395,40 @@ EXPORT_SYMBOL(dma_pool_destroy); void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle) { - unsigned long flags; + struct dma_block *block; struct dma_page *page; - unsigned int offset; - void *retval; + unsigned long flags; might_alloc(mem_flags); spin_lock_irqsave(&pool->lock, flags); - list_for_each_entry(page, &pool->page_list, page_list) { - if (page->offset < pool->allocation) - goto ready; - } - - /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */ - spin_unlock_irqrestore(&pool->lock, flags); - - page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO)); - if (!page) - return NULL; + block = pool_block_pop(pool); + if (!block) { + /* + * pool_alloc_page() might sleep, so temporarily drop + * &pool->lock + */ + spin_unlock_irqrestore(&pool->lock, flags); - spin_lock_irqsave(&pool->lock, flags); + page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO)); + if (!page) + return NULL; - list_add(&page->page_list, &pool->page_list); - ready: - page->in_use++; - offset = page->offset; - page->offset = *(int *)(page->vaddr + offset); - retval = offset + page->vaddr; - *handle = offset + page->dma; - pool_check_block(pool, retval, offset, mem_flags); + spin_lock_irqsave(&pool->lock, flags); + pool_initialise_page(pool, page); + block = pool_block_pop(pool); + } spin_unlock_irqrestore(&pool->lock, flags); + *handle = block->dma; + pool_check_block(pool, block, mem_flags); if (want_init_on_alloc(mem_flags)) - memset(retval, 0, pool->size); + memset(block, 0, pool->size); - return retval; + return block; } EXPORT_SYMBOL(dma_pool_alloc); -static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) -{ - struct dma_page *page; - - list_for_each_entry(page, &pool->page_list, page_list) { - if (dma < page->dma) - continue; - if ((dma - page->dma) < pool->allocation) - return page; - } - return NULL; -} - /** * dma_pool_free - put block back into dma pool * @pool: the dma pool holding the block @@ -431,31 +440,14 @@ static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) */ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma) { - struct dma_page *page; + struct dma_block *block = vaddr; unsigned long flags; spin_lock_irqsave(&pool->lock, flags); - page = pool_find_page(pool, dma); - if (!page) { - spin_unlock_irqrestore(&pool->lock, flags); - dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n", - __func__, pool->name, vaddr, &dma); - return; + if (!pool_block_err(pool, vaddr, dma)) { + pool_block_push(pool, block, dma); + pool->nr_active--; } - - if (pool_page_err(pool, page, vaddr, dma)) { - spin_unlock_irqrestore(&pool->lock, flags); - return; - } - - page->in_use--; - *(int *)vaddr = page->offset; - page->offset = vaddr - page->vaddr; - /* - * Resist a temptation to do - * if (!is_page_busy(page)) pool_free_page(pool, page); - * Better have a few empty pages hang around. - */ spin_unlock_irqrestore(&pool->lock, flags); } EXPORT_SYMBOL(dma_pool_free);

[PATCHv4,11/12] dmapool: link blocks across pages

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