[CRIU] [PATCH] cr-restore: optimize {loginuid, oom_score_adj} restoring

[Pavel Emelyanov]

On 12/18/2015 02:23 PM, Dmitry Safonov wrote:
> 1. Use PROC_SELF instead pid as prepare_pid_* used on restore only to
> set value to current process.
> 2. Do not set default values.

OK, plz, send the 3rd optimization as separate patch -- if loginuid
and oom score matches those from parent -- skip restore too.

> Signed-off-by: Dmitry Safonov <dsafonov at odin.com>
> ---
>  cr-restore.c | 25 ++++++++++++-------------
>  1 file changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/cr-restore.c b/cr-restore.c
> index aade3bc..d651e19 100644
> --- a/cr-restore.c
> +++ b/cr-restore.c
> @@ -840,20 +840,19 @@ err:
>  	return -1;
>  }
>  
> -static int prepare_pid_oom_score_adj(pid_t pid, int value)
> +static int prepare_oom_score_adj(int value)
>  {
>  	int fd, ret = 0;
>  	char buf[11];
>  
> -	fd = open_proc_rw(pid, "oom_score_adj");
> +	fd = open_proc_rw(PROC_SELF, "oom_score_adj");
>  	if (fd < 0)
>  		return -1;
>  
>  	snprintf(buf, 11, "%d", value);
>  
>  	if (write(fd, buf, 11) < 0) {
> -		pr_perror("Write %s to /proc/%d/oom_score_adj failed",
> -			buf, pid);
> +		pr_perror("Write %s to /proc/self/oom_score_adj failed", buf);
>  		ret = -1;
>  	}
>  
> @@ -861,19 +860,19 @@ static int prepare_pid_oom_score_adj(pid_t pid, int value)
>  	return ret;
>  }
>  
> -static int prepare_pid_loginuid(pid_t pid, unsigned int value)
> +static int prepare_loginuid(unsigned int value)
>  {
>  	int fd, ret = 0;
>  	char buf[11]; /* 4294967295 is maximum for u32 */
>  
> -	fd = open_proc_rw(pid, "loginuid");
> +	fd = open_proc_rw(PROC_SELF, "loginuid");
>  	if (fd < 0)
>  		return -1;
>  
>  	snprintf(buf, 11, "%u", value);
>  
>  	if (write(fd, buf, 11) < 0) {
> -		pr_perror("Write %s to /proc/%d/loginuid failed", buf, pid);
> +		pr_perror("Write %s to /proc/self/loginuid failed", buf);
>  		ret = -1;
>  	}
>  	close(fd);
> @@ -885,15 +884,15 @@ static int prepare_proc_misc(pid_t pid, TaskCoreEntry *tc)
>  	int ret;
>  
>  	/* loginuid value is critical to restore */
> -	if (tc->has_loginuid) {
> -		ret = prepare_pid_loginuid(pid, tc->loginuid);
> +	if (tc->has_loginuid && tc->loginuid != INVALID_UID) {
> +		ret = prepare_loginuid(tc->loginuid);
>  		if (ret < 0)
>  			return ret;
>  	}
>  
>  	/* oom_score_adj is not critical: only log errors */
> -	if (tc->has_oom_score_adj)
> -		prepare_pid_oom_score_adj(pid, tc->oom_score_adj);
> +	if (tc->has_oom_score_adj && tc->oom_score_adj != 0)
> +		prepare_oom_score_adj(tc->oom_score_adj);
>  
>  	return 0;
>  }
> @@ -1854,7 +1853,7 @@ static int prepare_userns_hook(void)
>  	if (ret < 0)
>  		return -1;
>  
> -	if (prepare_pid_loginuid(pid, INVALID_UID) < 0) {
> +	if (prepare_loginuid(INVALID_UID) < 0) {
>  		pr_err("Setting loginuid for CT init task failed, CAP_AUDIT_CONTROL?");
>  		return -1;
>  	}
> @@ -1864,7 +1863,7 @@ static int prepare_userns_hook(void)
>  static void restore_origin_ns_hook(void)
>  {
>  	/* not critical: it does not affect CT in any way */
> -	if (prepare_pid_loginuid(getpid(), saved_loginuid) < 0)
> +	if (prepare_loginuid(saved_loginuid) < 0)
>  		pr_err("Restore original /proc/self/loginuid failed");
>  }
>  
>