On Mon, Jul 31, 2023 at 03:42:47PM -0700, Mike Tipton wrote:
> +static int icc_get_set(void *data, u64 val)
> +{
> + struct debugfs_path *debugfs_path;
> + char *src, *dst;
> + int ret = 0;
> +
> + mutex_lock(&debugfs_lock);
> +
> + rcu_read_lock();
> + src = rcu_dereference(src_node);
> + dst = rcu_dereference(dst_node);
> +
> + /*
> + * If we've already looked up a path, then use the existing one instead
> + * of calling icc_get() again. This allows for updating previous BW
> + * votes when "get" is written to multiple times for multiple paths.
> + */
> + cur_path = get_path(src, dst);
> + if (cur_path) {
> + rcu_read_unlock();
> + goto out;
> + }
> +
> + src = kstrdup(src, GFP_KERNEL);
> + dst = kstrdup(dst, GFP_KERNEL);
> + rcu_read_unlock();
> +
Blocking calls are not allowed from RCU critical section. So we would
need to replace GFP_KERNEL with GFP_ATOMIC.
> + if (!src || !dst) {
> + ret = -ENOMEM;
> + goto err_free;
> + }
> +
> + cur_path = icc_get(&pdev->dev, src, dst);
> + if (IS_ERR(cur_path)) {
> + ret = PTR_ERR(cur_path);
> + goto err_free;
> + }
> +
> + debugfs_path = kzalloc(sizeof(*debugfs_path), GFP_KERNEL);
> + if (!debugfs_path) {
> + ret = -ENOMEM;
> + goto err_put;
> + }
> +
> + debugfs_path->path = cur_path;
> + debugfs_path->src = src;
> + debugfs_path->dst = dst;
> + list_add_tail(&debugfs_path->list, &debugfs_paths);
> +
> + goto out;
> +
> +err_put:
> + icc_put(cur_path);
> +err_free:
> + kfree(src);
> + kfree(dst);
> +out:
> + mutex_unlock(&debugfs_lock);
> + return ret;
> +}
