[CRIU] [PATCH v7 01/15] sysctl: add CTL_FLAGS_HAS to mark successful sysctl_op request

[Pavel Emelyanov]

On 04/28/2016 07:38 PM, Pavel Tikhomirov wrote:
> v4: replace separate has pointer to CTL_FLAGS_HAS flag, second part in
> patch "net/ipv4: add net_conf_op to reuse for ipv6"
> v6: define CTL_FLAGS_HAS
> v7: also allow EIO on do_sysctl_op for optional sysctls like
> stable_secret and fix sysctl file to close in error path

Wait a second. If we've managed to open a sysctl file, but failed to write into
it, why should we pretend as if there was not this sysctl at all?

> 
> https://jira.sw.ru/browse/PSBM-30942
> 
> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
> ---
>  criu/include/sysctl.h |  1 +
>  criu/sysctl.c         | 21 +++++++++++++++++----
>  2 files changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/criu/include/sysctl.h b/criu/include/sysctl.h
> index b949a40..3611ef1 100644
> --- a/criu/include/sysctl.h
> +++ b/criu/include/sysctl.h
> @@ -35,5 +35,6 @@ enum {
>   * Some entries might be missing mark them as optional.
>   */
>  #define CTL_FLAGS_OPTIONAL	1
> +#define CTL_FLAGS_HAS		2
>  
>  #endif /* __CR_SYSCTL_H__ */
> diff --git a/criu/sysctl.c b/criu/sysctl.c
> index 21ae4ce..60e52db 100644
> --- a/criu/sysctl.c
> +++ b/criu/sysctl.c
> @@ -303,8 +303,13 @@ static int __userns_sysctl_op(void *arg, int proc_fd, pid_t pid)
>  		close(nsfd);
>  
>  		for (i = 0; i < userns_req->nr_req; i++) {
> -			if (do_sysctl_op(fds[i], reqs[i], op) < 0)
> -				exit(1);
> +			if (do_sysctl_op(fds[i], reqs[i], op) < 0) {
> +				if (errno != EIO || !(req->flags & CTL_FLAGS_OPTIONAL))
> +					exit(1);
> +			} else {
> +				/* mark sysctl in question exists */
> +				req->flags |= CTL_FLAGS_HAS;
> +			}
>  		}
>  
>  		exit(0);
> @@ -372,8 +377,16 @@ static int __nonuserns_sysctl_op(struct sysctl_req *req, size_t nr_req, int op)
>  		}
>  
>  		ret = do_sysctl_op(fd, req, op);
> -		if (ret)
> -			goto out;
> +		if (ret) {
> +			if (errno != EIO || !(req->flags & CTL_FLAGS_OPTIONAL)) {
> +				close(fd);
> +				goto out;
> +			}
> +		} else {
> +			/* mark sysctl in question exists */
> +			req->flags |= CTL_FLAGS_HAS;
> +		}
> +
>  		close(fd);
>  		req++;
>  	}
>