[CRIU] [PATCH] Query Dirty Tracking support via RPC

[Pavel Emelyanov]

On 09/28/2015 05:17 PM, Adrian Reber wrote:
> From: Adrian Reber <areber at redhat.com>
> 
> There are still systems which do not support dirty memory tracking.
> This offers an interface to query the dirty memory tracking
> availability via RPC. This is in preparation of a p.haul change
> which will use this RPC interface to automatically detect if
> pre-dumps should be executed or not.

Yes, definitely needed change. Can we however slightly generalize it
and introduce the CRIU_REQ_TYPE__FEATURE_CHECK and a message containing
a set of optional bool something bits for individual features the
requester wants to check. The responce can be the same message with
the respective bits set to True when supported.

-- Pavel

> Signed-off-by: Adrian Reber <areber at redhat.com>
> ---
>  cr-service.c       | 47 +++++++++++++++++++++++++++++++++++++++++++++++
>  protobuf/rpc.proto |  2 ++
>  2 files changed, 49 insertions(+)
> 
> diff --git a/cr-service.c b/cr-service.c
> index 938ea9e..53ea6e2 100644
> --- a/cr-service.c
> +++ b/cr-service.c
> @@ -32,6 +32,7 @@
>  #include "security.h"
>  #include "sockets.h"
>  #include "irmap.h"
> +#include "kerndat.h"
>  
>  #include "setproctitle.h"
>  
> @@ -723,10 +724,53 @@ static int chk_keepopen_req(CriuReq *msg)
>  	else if (msg->type == CRIU_REQ_TYPE__CPUINFO_DUMP ||
>  		 msg->type == CRIU_REQ_TYPE__CPUINFO_CHECK)
>  		return 0;
> +	else if (msg->type == CRIU_REQ_TYPE__DIRTY_TRACKING)
> +		return 0;
>  
>  	return -1;
>  }
>  
> +static int handle_dirty_tracking(int sk, CriuReq *msg)
> +{
> +	CriuResp resp = CRIU_RESP__INIT;
> +	bool success = false;
> +	int pid, status;
> +
> +	pid = fork();
> +	if (pid < 0) {
> +		pr_perror("Can't fork");
> +		goto out;
> +	}
> +
> +	if (pid == 0) {
> +		int ret = 1;
> +
> +		if (setup_opts_from_req(sk, msg->opts))
> +			goto cout;
> +
> +		setproctitle("dirty-tracking --rpc -D %s",
> +			     images_dir);
> +
> +		kerndat_get_dirty_track();
> +
> +		if (kdat.has_dirty_track)
> +			ret = 0;
> +cout:
> +		exit(ret);
> +	}
> +
> +	wait(&status);
> +	if (!WIFEXITED(status) || WEXITSTATUS(status))
> +		goto out;
> +
> +	success = true;
> +out:
> +	resp.type = msg->type;
> +	resp.success = success;
> +
> +	return send_criu_msg(sk, &resp);
> +}
> +
>  static int handle_cpuinfo(int sk, CriuReq *msg)
>  {
>  	CriuResp resp = CRIU_RESP__INIT;
> @@ -804,6 +848,9 @@ more:
>  	case CRIU_REQ_TYPE__CPUINFO_CHECK:
>  		ret = handle_cpuinfo(sk, msg);
>  		break;
> +	case CRIU_REQ_TYPE__DIRTY_TRACKING:
> +		ret = handle_dirty_tracking(sk, msg);
> +		break;
>  
>  	default:
>  		send_criu_err(sk, "Invalid req");
> diff --git a/protobuf/rpc.proto b/protobuf/rpc.proto
> index 466780e..1f0e66e 100644
> --- a/protobuf/rpc.proto
> +++ b/protobuf/rpc.proto
> @@ -115,6 +115,8 @@ enum criu_req_type {
>  
>  	CPUINFO_DUMP	= 7;
>  	CPUINFO_CHECK	= 8;
> +
> +	DIRTY_TRACKING	= 9;
>  }
>  
>  /*
>