Re: [dpdk-dev] [PATCH v5 4/5] vhost: eventfd_link: replace copy-pasted sys_close

["Xie, Huawei" <huawei.xie@intel.com>]

On 4/16/2015 7:48 PM, Pavel Boldin wrote:
> Replace copy-pasted `fget_from_files' -> `filp_close' with
> a `sys_close' call.
>
> Signed-off-by: Pavel Boldin <pboldin@mirantis.com>
> ---
>  lib/librte_vhost/eventfd_link/eventfd_link.c | 49 +++++++---------------------
>  1 file changed, 12 insertions(+), 37 deletions(-)
>
> diff --git a/lib/librte_vhost/eventfd_link/eventfd_link.c b/lib/librte_vhost/eventfd_link/eventfd_link.c
> index 0a06594..9bc52a3 100644
> --- a/lib/librte_vhost/eventfd_link/eventfd_link.c
> +++ b/lib/librte_vhost/eventfd_link/eventfd_link.c
> @@ -88,9 +88,8 @@ eventfd_link_ioctl_copy(unsigned long arg)
>  {
>  
> +	/* Closing the source_fd */
> +	ret = sys_close(eventfd_copy.source_fd);
Pavel:
Here we close the fd and re-install a new file on this fd later. 
sys_close does all cleanup.
But, for instance, if we allocate new fd later, normally it will reuse
the just freed fds by sys_close, is there issue here? 

> +	if (ret)
>  		goto out_task;
> -	}
> -
> -	/*
> -	 * Release the existing eventfd in the source process
> -	 */
> -	spin_lock(&files->file_lock);
> -	fput(file);
> -	filp_close(file, files);
> -	fdt = files_fdtable(files);
> -	fdt->fd[eventfd_copy.source_fd] = NULL;
> -	spin_unlock(&files->file_lock);
> -
> -	put_files_struct(files);
> +	ret = -ESTALE;
>  
>  	/*
>  	 * Find the file struct associated with the target fd.
>  	 */
>  
> -	ret = -ESTALE;
> -	files = get_files_struct(task_target);
> -	if (files == NULL) {
> +	target_files = get_files_struct(task_target);
> +	if (target_files == NULL) {
>  		pr_info("Failed to get target files struct\n");
>  		goto out_task;
>  	}
>  
>  	ret = -EBADF;
> -	file = fget_from_files(files, eventfd_copy.target_fd);
> -	put_files_struct(files);
> +	target_file = fget_from_files(target_files, eventfd_copy.target_fd);
> +	put_files_struct(target_files);
>  
> -	if (file == NULL) {
> +	if (target_file == NULL) {
>  		pr_info("Failed to get fd %d from target\n",
>  			eventfd_copy.target_fd);
>  		goto out_task;
> @@ -164,7 +139,7 @@ eventfd_link_ioctl_copy(unsigned long arg)
>  	 * file desciptor of the source process,
>  	 */
>  
> -	fd_install(eventfd_copy.source_fd, file);
> +	fd_install(eventfd_copy.source_fd, target_file);
>  	ret = 0;
>  
>  out_task: