diff options
| -rw-r--r-- | mm/dmapool.c | 43 |
1 files changed, 35 insertions, 8 deletions
diff --git a/mm/dmapool.c b/mm/dmapool.c index ba8019b063e1..2372ed5a33d3 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -62,6 +62,7 @@ struct dma_page { /* cacheable header for 'allocation' bytes */ }; static DEFINE_MUTEX(pools_lock); +static DEFINE_MUTEX(pools_reg_lock); static ssize_t show_pools(struct device *dev, struct device_attribute *attr, char *buf) @@ -132,6 +133,7 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, { struct dma_pool *retval; size_t allocation; + bool empty = false; if (align == 0) { align = 1; @@ -172,15 +174,34 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, INIT_LIST_HEAD(&retval->pools); + /* + * pools_lock ensures that the ->dma_pools list does not get corrupted. + * pools_reg_lock ensures that there is not a race between + * dma_pool_create() and dma_pool_destroy() or within dma_pool_create() + * when the first invocation of dma_pool_create() failed on + * device_create_file() and the second assumes that it has been done (I + * know it is a short window). + */ + mutex_lock(&pools_reg_lock); mutex_lock(&pools_lock); - if (list_empty(&dev->dma_pools) && - device_create_file(dev, &dev_attr_pools)) { - kfree(retval); - retval = NULL; - } else - list_add(&retval->pools, &dev->dma_pools); + if (list_empty(&dev->dma_pools)) + empty = true; + list_add(&retval->pools, &dev->dma_pools); mutex_unlock(&pools_lock); - + if (empty) { + int err; + + err = device_create_file(dev, &dev_attr_pools); + if (err) { + mutex_lock(&pools_lock); + list_del(&retval->pools); + mutex_unlock(&pools_lock); + mutex_unlock(&pools_reg_lock); + kfree(retval); + return NULL; + } + } + mutex_unlock(&pools_reg_lock); return retval; } EXPORT_SYMBOL(dma_pool_create); @@ -251,11 +272,17 @@ static void pool_free_page(struct dma_pool *pool, struct dma_page *page) */ void dma_pool_destroy(struct dma_pool *pool) { + bool empty = false; + + mutex_lock(&pools_reg_lock); mutex_lock(&pools_lock); list_del(&pool->pools); if (pool->dev && list_empty(&pool->dev->dma_pools)) - device_remove_file(pool->dev, &dev_attr_pools); + empty = true; mutex_unlock(&pools_lock); + if (empty) + device_remove_file(pool->dev, &dev_attr_pools); + mutex_unlock(&pools_reg_lock); while (!list_empty(&pool->page_list)) { struct dma_page *page; |