[CRIU] [PATCH] sysctl: Use open_proc()

[Andrei Vagin]

Accepted, thanks!

On Fri, Apr 14, 2017 at 07:56:40PM +0300, Pavel Emelyanov wrote:
> Many of sysctl_op-s we have read (or write) single entry.
> In current implementaiton this results in two opens and
> two closes for each -- open /proc/sys, then open the rest.
> 
> It's better to use open_proc() as the latter already have
> fd for /proc cached.
> 
> Signed-off-by: Pavel Emelyanov <xemul at virtuozzo.com>
> ---
>  criu/sysctl.c | 17 ++++-------------
>  1 file changed, 4 insertions(+), 13 deletions(-)
> 
> diff --git a/criu/sysctl.c b/criu/sysctl.c
> index 1f3c9af..76349e0 100644
> --- a/criu/sysctl.c
> +++ b/criu/sysctl.c
> @@ -351,23 +351,15 @@ out:
>  
>  static int __nonuserns_sysctl_op(struct sysctl_req *req, size_t nr_req, int op)
>  {
> -	int dir, ret, exit_code = -1;;
> -
> -	dir = open("/proc/sys", O_RDONLY, O_DIRECTORY);
> -	if (dir < 0) {
> -		pr_perror("Can't open sysctl dir");
> -		return -1;
> -	}
> +	int ret, exit_code = -1;;
>  
>  	while (nr_req--) {
> -		int fd, flags;
> +		int fd;
>  
>  		if (op == CTL_READ)
> -			flags = O_RDONLY;
> +			fd = open_proc(PROC_GEN, "sys/%s", req->name);
>  		else
> -			flags = O_WRONLY;
> -
> -		fd = openat(dir, req->name, flags);
> +			fd = open_proc_rw(PROC_GEN, "sys/%s", req->name);
>  		if (fd < 0) {
>  			if (errno == ENOENT && (req->flags & CTL_FLAGS_OPTIONAL)) {
>  				req++;
> @@ -394,7 +386,6 @@ static int __nonuserns_sysctl_op(struct sysctl_req *req, size_t nr_req, int op)
>  
>  	exit_code = 0;
>  out:
> -	close(dir);
>  	return exit_code;
>  }
>  
> -- 
> 2.5.5
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