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.
Fixes: c02a81fba74f ("dma-buf: Add dma-buf heaps framework")
base-commit: 447fb14bf07905b880c9ed1ea92c53d6dd0649d7
Signed-off-by: Dawei Li set_pte_at@outlook.com --- drivers/dma-buf/dma-heap.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-)
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index 8f5848aa144f..1c787a147e3a 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -216,9 +216,21 @@ const char *dma_heap_get_name(struct dma_heap *heap) return heap->name; }
+static inline bool dma_heap_exist(const char *name) +{ + struct dma_heap *h; + + list_for_each_entry(h, &heap_list, list) { + if (!strcmp(h->name, name)) + return true; + } + + return false; +} + struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) { - struct dma_heap *heap, *h, *err_ret; + struct dma_heap *heap, *err_ret; struct device *dev_ret; unsigned int minor; int ret; @@ -235,13 +247,11 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
/* 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); - } + if (dma_heap_exist(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);
@@ -283,13 +293,22 @@ 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); + if (unlikely(dma_heap_exist(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; + } 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:
On Mon, Oct 31, 2022 at 7:53 AM Dawei Li set_pte_at@outlook.com 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.
Fixes: c02a81fba74f ("dma-buf: Add dma-buf heaps framework")
base-commit: 447fb14bf07905b880c9ed1ea92c53d6dd0649d7
Signed-off-by: Dawei Li set_pte_at@outlook.com
drivers/dma-buf/dma-heap.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-)
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index 8f5848aa144f..1c787a147e3a 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -216,9 +216,21 @@ const char *dma_heap_get_name(struct dma_heap *heap) return heap->name; }
+static inline bool dma_heap_exist(const char *name) +{
struct dma_heap *h;
list_for_each_entry(h, &heap_list, list) {
if (!strcmp(h->name, name))
return true;
}
return false;
+}
struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) {
struct dma_heap *heap, *h, *err_ret;
struct dma_heap *heap, *err_ret; struct device *dev_ret; unsigned int minor; int ret;
@@ -235,13 +247,11 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
/* 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);
}
if (dma_heap_exist(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);
Hi Dawei, What Andrew was suggesting was that you entirely move the check from here to the critical section down below, not duplicate the check. I don't think we want to check this twice. We should be able to do this by taking the heap_list_lock only once.
} mutex_unlock(&heap_list_lock);
@@ -283,13 +293,22 @@ 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);
if (unlikely(dma_heap_exist(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;
} 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
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