On Sat, Nov 05, 2022 at 12:05:36AM +0800, Dawei Li wrote:
Hi Christian, May I have your opinion on this change?
Thanks, Dawei
Racing conflict could be: task A task B list_for_each_entry strcmp(h->name)) list_for_each_entry strcmp(h->name) kzalloc kzalloc ...... ..... device_create device_create list_add list_add
The root cause is that task B has no idea about the fact someone else(A) has inserted heap with same name when it calls list_add, so a potential collision occurs.
Fixes: c02a81fba74f ("dma-buf: Add dma-buf heaps framework") Signed-off-by: Dawei Li set_pte_at@outlook.com
v1: https://lore.kernel.org/all/TYCP286MB2323950197F60FC3473123B7CA349@TYCP286MB... v1->v2: Narrow down locking scope, check the existence of heap before insertion, as suggested by Andrew Davis. v2->v3: Remove double checking. v3->v4: Minor coding style and patch formatting adjustment.
drivers/dma-buf/dma-heap.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index 8f5848aa144f..59d158873f4c 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -233,18 +233,6 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) return ERR_PTR(-EINVAL); }
- /* check the name is unique */
- mutex_lock(&heap_list_lock);
- list_for_each_entry(h, &heap_list, list) {
if (!strcmp(h->name, exp_info->name)) {mutex_unlock(&heap_list_lock);pr_err("dma_heap: Already registered heap named %s\n",exp_info->name);return ERR_PTR(-EINVAL);}- }
- mutex_unlock(&heap_list_lock);
- heap = kzalloc(sizeof(*heap), GFP_KERNEL); if (!heap) return ERR_PTR(-ENOMEM);
@@ -283,13 +271,27 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) err_ret = ERR_CAST(dev_ret); goto err2; }
- /* Add heap to the list */
- mutex_lock(&heap_list_lock);
- /* check the name is unique */
- list_for_each_entry(h, &heap_list, list) {
if (!strcmp(h->name, exp_info->name)) {mutex_unlock(&heap_list_lock);pr_err("dma_heap: Already registered heap named %s\n",exp_info->name);err_ret = ERR_PTR(-EINVAL);goto err3;}- }
- /* Add heap to the list */ list_add(&heap->list, &heap_list); mutex_unlock(&heap_list_lock);
return heap; +err3:
- device_destroy(dma_heap_class, heap->heap_devt);
err2: cdev_del(&heap->heap_cdev); err1: -- 2.25.1