[dpdk-dev] [PATCH v6 1/2] eal: add channel for multi-process communication
Burakov, Anatoly
anatoly.burakov at intel.com
Fri Jan 26 11:25:45 CET 2018
On 26-Jan-18 3:41 AM, Jianfeng Tan wrote:
> Previouly, there are three channels for multi-process
> (i.e., primary/secondary) communication.
> 1. Config-file based channel, in which, the primary process writes
> info into a pre-defined config file, and the secondary process
> reads the info out.
> 2. vfio submodule has its own channel based on unix socket for the
> secondary process to get container fd and group fd from the
> primary process.
> 3. pdump submodule also has its own channel based on unix socket for
> packet dump.
>
> It'd be good to have a generic communication channel for multi-process
> communication to accommodate the requirements including:
> a. Secondary wants to send info to primary, for example, secondary
> would like to send request (about some specific vdev to primary).
> b. Sending info at any time, instead of just initialization time.
> c. Share FDs with the other side, for vdev like vhost, related FDs
> (memory region, kick) should be shared.
> d. A send message request needs the other side to response immediately.
>
> This patch proposes to create a communication channel, based on datagram
> unix socket, for above requirements. Each process will block on a unix
> socket waiting for messages from the peers.
>
> Three new APIs are added:
>
> 1. rte_eal_mp_action_register() is used to register an action,
> indexed by a string, when a component at receiver side would like
> to response the messages from the peer processe.
> 2. rte_eal_mp_action_unregister() is used to unregister the action
> if the calling component does not want to response the messages.
> 3. rte_eal_mp_sendmsg() is used to send a message, and returns
> immediately. If there are n secondary processes, the primary
> process will send n messages.
>
> Suggested-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
> Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>
> Reviewed-by: Anatoly Burakov <anatoly.burakov at intel.com>
> Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
> ---
<snip>
> +
> +static int
> +mp_send(struct rte_mp_msg *msg)
> +{
> + int ret = 0;
> + DIR *mp_dir;
> + struct dirent *ent;
> +
> + if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
> + if (send_msg(eal_mp_socket_path(), msg) < 0)
> + return -1;
> + else
> + return 0;
> + }
> +
> + /* broadcast to all secondary processes */
> + mp_dir = opendir(mp_dir_path);
> + if (!mp_dir) {
> + RTE_LOG(ERR, EAL, "Unable to open directory %s\n",
> + mp_dir_path);
> + rte_errno = errno;
> + return -1;
> + }
> + while ((ent = readdir(mp_dir))) {
> + if (fnmatch(mp_filter, ent->d_name, 0) != 0)
> + continue;
> +
> + if (send_msg(ent->d_name, msg) < 0)
> + ret = -1;
> + }
> + closedir(mp_dir);
> +
> + return ret;
Nitpick: you probably don't need ret here, just return 0 as in other places.
> +}
> +
> +static bool
> +check_input(const struct rte_mp_msg *msg)
> +{
> + if (msg == NULL) {
> + RTE_LOG(ERR, EAL, "Msg cannot be NULL\n");
> + rte_errno = -EINVAL;
> + return false;
> + }
> +
> + if (validate_action_name(msg->name))
> + return false;
> +
> + if (msg->len_param > RTE_MP_MAX_PARAM_LEN) {
> + RTE_LOG(ERR, EAL, "Message data is too long\n");
> + rte_errno = -E2BIG;
> + return false;
> + }
> +
> + if (msg->num_fds > RTE_MP_MAX_FD_NUM) {
> + RTE_LOG(ERR, EAL, "Cannot send more than %d FDs\n",
> + RTE_MP_MAX_FD_NUM);
> + rte_errno = -E2BIG;
> + return false;
Otherwise, i'm happy with this patch.
--
Thanks,
Anatoly
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