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-rw-r--r--mm/dmapool.c43
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;

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