[CRIU] [PATCH] criu: add an option to skip in-flight connections

[Andrew Vagin]

On Tue, Jun 14, 2016 at 07:13:26AM +0000, Adrian Reber wrote:
> From: Adrian Reber <areber at redhat.com>
> 
> Trying to migrate containers with tomcat and running ab as a test client
> (ab -n 1000000 -c 20 http://url/to/test) criu sometimes exited with an
> error if in-flight connections were detected. Criu can handle sockets
> listening and with established connection. In-flight connections can
> happen on sockets which do not yet have a full established connection
> (SYN, SYN-ACK, and the last ACK is missing).
> 
> This adds a new option to criu:
> 
>  --skip-in-flight  this option skips in-flight TCP connections.
>                    if TCP connections are found which are not yet completely
>                    established, criu will ignore these connections in favor
>                    of erroring out.
> 
> With this option criu will skip sockets in this state and let's the client
> handle the re-connection.
>

Acked-by: Andrew Vagin <avagin at virtuozzo.com> 
> Signed-off-by: Adrian Reber <areber at redhat.com>
> ---
>  criu/crtools.c            | 9 +++++++++
>  criu/include/cr_options.h | 1 +
>  criu/include/sk-inet.h    | 1 +
>  criu/sk-inet.c            | 7 +++++++
>  4 files changed, 18 insertions(+)
> 
> diff --git a/criu/crtools.c b/criu/crtools.c
> index b7b205c..5729fc3 100644
> --- a/criu/crtools.c
> +++ b/criu/crtools.c
> @@ -324,6 +324,7 @@ int main(int argc, char *argv[], char *envp[])
>  		{ "cgroup-props",		required_argument,	0, 1080	},
>  		{ "cgroup-props-file",		required_argument,	0, 1081	},
>  		{ "cgroup-dump-controller",	required_argument,	0, 1082	},
> +		{ SK_INFLIGHT_PARAM,		no_argument,		0, 1083	},
>  		{ },
>  	};
>  
> @@ -635,6 +636,10 @@ int main(int argc, char *argv[], char *envp[])
>  			if (!cgp_add_dump_controller(optarg))
>  				return 1;
>  			break;
> +		case 1083:
> +			pr_msg("Will skip in-flight TCP connections\n");
> +			opts.tcp_skip_in_flight = true;
> +			break;
>  		case 'V':
>  			pr_msg("Version: %s\n", CRIU_VERSION);
>  			if (strcmp(CRIU_GITID, "0"))
> @@ -862,6 +867,10 @@ usage:
>  "* Special resources support:\n"
>  "  -x|--" USK_EXT_PARAM "inode,.." "      allow external unix connections (optionally can be assign socket's inode that allows one-sided dump)\n"
>  "     --" SK_EST_PARAM "  checkpoint/restore established TCP connections\n"
> +"     --" SK_INFLIGHT_PARAM "   this option skips in-flight TCP connections.\n"
> +"                        if TCP connections are found which are not yet completely\n"
> +"                        established, criu will ignore these connections in favor\n"
> +"                        of erroring out.\n"
>  "  -r|--root PATH        change the root filesystem (when run in mount namespace)\n"
>  "  --evasive-devices     use any path to a device file if the original one\n"
>  "                        is inaccessible\n"
> diff --git a/criu/include/cr_options.h b/criu/include/cr_options.h
> index e36c362..1d47909 100644
> --- a/criu/include/cr_options.h
> +++ b/criu/include/cr_options.h
> @@ -111,6 +111,7 @@ struct cr_options {
>  	unsigned int		timeout;
>  	unsigned int		empty_ns;
>  	bool			lazy_pages;
> +	bool			tcp_skip_in_flight;
>  };
>  
>  extern struct cr_options opts;
> diff --git a/criu/include/sk-inet.h b/criu/include/sk-inet.h
> index 4707a6e..9d2bda6 100644
> --- a/criu/include/sk-inet.h
> +++ b/criu/include/sk-inet.h
> @@ -72,6 +72,7 @@ extern int dump_one_tcp(int sk, struct inet_sk_desc *sd);
>  extern int restore_one_tcp(int sk, struct inet_sk_info *si);
>  
>  #define SK_EST_PARAM	"tcp-established"
> +#define SK_INFLIGHT_PARAM "skip-in-flight"
>  
>  extern int check_tcp(void);
>  
> diff --git a/criu/sk-inet.c b/criu/sk-inet.c
> index 20c6535..dfcfae6 100644
> --- a/criu/sk-inet.c
> +++ b/criu/sk-inet.c
> @@ -144,6 +144,11 @@ static int can_dump_inet_sk(const struct inet_sk_desc *sk)
>  	switch (sk->state) {
>  	case TCP_LISTEN:
>  		if (sk->rqlen != 0) {
> +			if (opts.tcp_skip_in_flight) {
> +				pr_info("Skipping in-flight connection (l) for %x\n",
> +						sk->sd.ino);
> +				break;
> +			}
>  			/*
>  			 * Currently the ICONS nla reports the conn
>  			 * requests for listen sockets. Need to pick
> @@ -151,6 +156,8 @@ static int can_dump_inet_sk(const struct inet_sk_desc *sk)
>  			 */
>  			pr_err("In-flight connection (l) for %x\n",
>  					sk->sd.ino);
> +			pr_err("In-flight connections can be ignored with the"
> +					"--%s option.\n", SK_INFLIGHT_PARAM);
>  			return 0;
>  		}
>  		break;
> -- 
> 1.8.3.1
> 
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