On 11/2/22 10:58 AM, Dawei Li wrote:
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.
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.
The above version info should be in a cover letter or below the --- line so it doesn't end up in the commit message in tree.
Fixes: c02a81fba74f ("dma-buf: Add dma-buf heaps framework")
base-commit: 447fb14bf07905b880c9ed1ea92c53d6dd0649d7
Same as above, plus this is an odd base, maybe just use "v6.1-rc2".
Signed-off-by: Dawei Li set_pte_at@outlook.com
drivers/dma-buf/dma-heap.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index 8f5848aa144f..7a25e98259ea 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 +271,26 @@ 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;
Would like to keep this new line after the return statement.
Andrew
+err3:
- device_destroy(dma_heap_class, heap->heap_devt); err2: cdev_del(&heap->heap_cdev); err1: