[dpdk-dev] [PATCH v2 3/4] eal: add synchronous multi-process communication

[Burakov, Anatoly]

On 11-Jan-18 4:07 AM, Jianfeng Tan wrote:
> ---
>   lib/librte_eal/common/eal_common_proc.c | 144 +++++++++++++++++++++++++++++---
>   lib/librte_eal/common/include/rte_eal.h |  73 +++++++++++++++-
>   lib/librte_eal/rte_eal_version.map      |   2 +
>   3 files changed, 206 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/librte_eal/common/eal_common_proc.c b/lib/librte_eal/common/eal_common_proc.c
> index 70519cc..f194a52 100644
> --- a/lib/librte_eal/common/eal_common_proc.c
> +++ b/lib/librte_eal/common/eal_common_proc.c
> @@ -32,6 +32,7 @@
>   static int mp_fd = -1;
>   static char *mp_sec_sockets[MAX_SECONDARY_PROCS];
>   static pthread_mutex_t mp_mutex_action = PTHREAD_MUTEX_INITIALIZER;
> +static pthread_mutex_t mp_mutex_request = PTHREAD_MUTEX_INITIALIZER;
>   
>   struct action_entry {
>   	TAILQ_ENTRY(action_entry) next;      /**< Next attached action entry */
> @@ -49,6 +50,10 @@ static struct action_entry_list action_entry_list =
>   
>   struct mp_msghdr {
>   	char action_name[MAX_ACTION_NAME_LEN];
> +#define MP_MSG	0 /* Share message with peers, will not block */
> +#define MP_REQ	1 /* Request for information, Will block for a reply */
> +#define MP_REP	2 /* Reply to previously-received request */

nitpicking, but... response instead of reply?

> +	int type;
>   	int fds_num;
>   	int len_params;
>   	char params[0];
> @@ -138,7 +143,8 @@ rte_eal_mp_action_unregister(const char *name)
>   }
>   
>   static int
> -read_msg(int fd, char *buf, int buflen, int *fds, int fds_num)
> +read_msg(int fd, char *buf, int buflen,
> +	 int *fds, int fds_num, struct sockaddr_un *s)

<snip>

> +	return mp_send(action_name, params, len_params,
> +			fds, fds_num, MP_MSG, NULL);
> +}
> +
> +int
> +rte_eal_mp_request(const char *action_name,
> +		   void *params,
> +		   int len_p,
> +		   int fds[],
> +		   int fds_in,
> +		   int fds_out)

name == NULL? name too long?

> +{
> +	int i, j;
> +	int sockfd;
> +	int nprocs;
> +	int ret = 0;
> +	struct mp_msghdr *req;
> +	struct timeval tv;
> +	char buf[MAX_MSG_LENGTH];
> +	struct mp_msghdr *hdr;
> +
> +	RTE_LOG(DEBUG, EAL, "request: %s\n", action_name);
> +
> +	if (fds_in > SCM_MAX_FD || fds_out > SCM_MAX_FD) {
> +		RTE_LOG(ERR, EAL, "Cannot send more than %d FDs\n", SCM_MAX_FD);
> +		rte_errno = -E2BIG;

(this also applies to previous patches) you set rte_errno to -EINVAL in 
format_msg when message with parameters is too big - should that be 
setting -E2BIG as well? Also, maybe not set rte_errno in multiple 
places, and put all parameter checking (or at least errno setting) in 
rte_eal_mp_* functions?

> +		return 0;
> +	}
> +
> +	req = format_msg(action_name, params, len_p, fds_in, MP_REQ);
> +	if (req == NULL)
> +		return 0;
> +
> +	if ((sockfd = open_unix_fd(0)) < 0) {
> +		free(req);
> +		return 0;
> +	}
> +
> +	tv.tv_sec = 5;  /* 5 Secs Timeout */
> +	tv.tv_usec = 0;
> +	if (setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO,
> +			(const void *)&tv, sizeof(struct timeval)) < 0)
> +		RTE_LOG(INFO, EAL, "Failed to set recv timeout\n");
> +
> +	/* Only allow one req at a time */
> +	pthread_mutex_lock(&mp_mutex_request);
> +
> +	if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
> +		nprocs = 0;
> +		for (i = 0; i < MAX_SECONDARY_PROCS; ++i)

What follows is a bit confusing, some comments explaining what happens 
and maybe more informative variable names would've been helpful.

> +			if (!mp_sec_sockets[i]) {
> +				j = i;
> +				nprocs++;
> +			}
> +
> +		if (nprocs > 1) {
> +			RTE_LOG(ERR, EAL,
> +				"multi secondary processes not supported\n");
> +			goto free_and_ret;
> +		}
> +

<snip>


-- 
Thanks,
Anatoly