[CRIU] [PATCH] [v2] zdtm: fix a race in socket_udp and socket_udplite

[Andrei Vagin]

Pls, ignore this ptach. The previous v2 is the right one.

On Fri, Jan 20, 2017 at 10:40:52PM +0300, Andrei Vagin wrote:
> From: Andrei Vagin <avagin at virtuozzo.com>
> 
> If we have two sockets and send an upd message from one to another,
> we can't be sure that it will be delivered immediately,
> there is a change to get from recv(..., MSG_DONTWAIT) EGAIN.
> 
> This message is handled asynchronously in a kernel space, so
> there may be a small timeout before we get it from another socket.
> 
> v2: fix socket6_udp too
> 
> Reported-by: Mr Travis
> Signed-off-by: Andrei Vagin <avagin at virtuozzo.com>
> ---
>  test/zdtm/lib/lock.c              | 7 ++++++-
>  test/zdtm/static/socket6_udp.c    | 4 ++--
>  test/zdtm/static/socket_udp.c     | 4 ++--
>  test/zdtm/static/socket_udplite.c | 4 ++--
>  4 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/test/zdtm/lib/lock.c b/test/zdtm/lib/lock.c
> index 9c3ec87..5a24581 100644
> --- a/test/zdtm/lib/lock.c
> +++ b/test/zdtm/lib/lock.c
> @@ -102,11 +102,16 @@ void task_waiter_wait4(task_waiter_t *t, unsigned int lockid)
>  	if (recv(t->sk, &v, sizeof(v), 0) != sizeof(v))
>  		goto err;
>  
> +	if (v != lockid) {
> +		pr_err("Got %d instead of %d", v, lockid);
> +		exit(1);
> +	}
> +
>  	return;
>  
>  err:
>  	pr_perror("task_waiter_wait4 failed");
> -	exit(errno);
> +	exit(1);
>  }
>  
>  void task_waiter_complete(task_waiter_t *t, unsigned int lockid)
> diff --git a/test/zdtm/static/socket6_udp.c b/test/zdtm/static/socket6_udp.c
> index 30ddc9a..d1c39c7 100644
> --- a/test/zdtm/static/socket6_udp.c
> +++ b/test/zdtm/static/socket6_udp.c
> @@ -85,7 +85,7 @@ int main(int argc, char **argv)
>  		return 1;
>  	}
>  
> -	ret = recvfrom(sk1, buf, sizeof(buf), MSG_DONTWAIT,
> +	ret = recvfrom(sk1, buf, sizeof(buf), 0,
>  			(struct sockaddr *)&addr, &len);
>  	if (ret <= 0) {
>  		fail("Can't recv C");
> @@ -102,7 +102,7 @@ int main(int argc, char **argv)
>  		return 1;
>  	}
>  
> -	ret = recvfrom(sk2, buf, sizeof(buf), MSG_DONTWAIT,
> +	ret = recvfrom(sk2, buf, sizeof(buf), 0,
>  			(struct sockaddr *)&addr, &len);
>  	if (ret <= 0) {
>  		fail("Can't recv");
> diff --git a/test/zdtm/static/socket_udp.c b/test/zdtm/static/socket_udp.c
> index e84e8bf..5e24a8b 100644
> --- a/test/zdtm/static/socket_udp.c
> +++ b/test/zdtm/static/socket_udp.c
> @@ -90,7 +90,7 @@ int main(int argc, char **argv)
>  		return 1;
>  	}
>  
> -	ret = recvfrom(sk1, buf, sizeof(buf), MSG_DONTWAIT,
> +	ret = recvfrom(sk1, buf, sizeof(buf), 0,
>  			(struct sockaddr *)&addr, &len);
>  	if (ret <= 0) {
>  		fail("Can't recv C");
> @@ -107,7 +107,7 @@ int main(int argc, char **argv)
>  		return 1;
>  	}
>  
> -	ret = recvfrom(sk2, buf, sizeof(buf), MSG_DONTWAIT,
> +	ret = recvfrom(sk2, buf, sizeof(buf), 0,
>  			(struct sockaddr *)&addr, &len);
>  	if (ret <= 0) {
>  		fail("Can't recv");
> diff --git a/test/zdtm/static/socket_udplite.c b/test/zdtm/static/socket_udplite.c
> index aaa40e1..8218ff5 100644
> --- a/test/zdtm/static/socket_udplite.c
> +++ b/test/zdtm/static/socket_udplite.c
> @@ -90,7 +90,7 @@ int main(int argc, char **argv)
>  		return 1;
>  	}
>  
> -	ret = recvfrom(sk1, buf, sizeof(buf), MSG_DONTWAIT,
> +	ret = recvfrom(sk1, buf, sizeof(buf), 0,
>  			(struct sockaddr *)&addr, &len);
>  	if (ret <= 0) {
>  		fail("Can't recv C");
> @@ -107,7 +107,7 @@ int main(int argc, char **argv)
>  		return 1;
>  	}
>  
> -	ret = recvfrom(sk2, buf, sizeof(buf), MSG_DONTWAIT,
> +	ret = recvfrom(sk2, buf, sizeof(buf), 0,
>  			(struct sockaddr *)&addr, &len);
>  	if (ret <= 0) {
>  		fail("Can't recv");
> -- 
> 2.7.4
>