>
> We need the synchronous way for multi-process communication,
> i.e., blockingly waiting for reply message when we send a request
> to the peer process.
>
> We add two APIs rte_eal_mp_request() and rte_eal_mp_reply() for
> such use case. By invoking rte_eal_mp_request(), a request message
> is sent out, and then it waits there for a reply message. The
> timeout is hard-coded 5 Sec. And the replied message will be copied
> in the parameters of this API so that the caller can decide how
> to translate those information (including params and fds). Note
> if a primary process owns multiple secondary processes, this API
> will fail.
>
> The API rte_eal_mp_reply() is always called by an mp action handler.
> Here we add another parameter for rte_eal_mp_t so that the action
> handler knows which peer address to reply.
>
> We use mutex in rte_eal_mp_request() to guarantee that only one
> request is on the fly for one pair of processes.
You don't need to do things in such strange and restrictive way.
Instead you can do something like that:
1) Introduce new struct, list for it and mutex
struct sync_request {
int reply_received;
char dst[PATH_MAX];
char reply[...];
LIST_ENTRY(sync_request) next;
};
static struct
LIST_HEAD(list, sync_request);
pthread_mutex_t lock;
pthead_cond_t cond;
} sync_requests;
2) then at request() call:
Grab sync_requests.lock
Check do we already have a pending request for that destination,
If yes - the release the lock and returns with error.
- allocate and init new sync_request struct, set reply_received=0
- do send_msg()
-then in a cycle:
pthread_cond_timed_wait(&sync_requests.cond, &sync_request.lock, ×pec);
- at return from it check if sync_request.reply_received == 1, if not
check if timeout expired and either return a failure or go to the start of the
cycle.
3) at mp_handler() if REPLY received - grab sync_request.lock,
search through sync_requests.list for dst[] ,
if found, then set it's reply_received=1, copy the received message into
reply
and call pthread_cond_braodcast((&sync_requests.cond);
>
> Suggested-by: Anatoly Burakov <anatoly.bura...@intel.com>
> Signed-off-by: Jianfeng Tan <jianfeng....@intel.com>
> ---
> 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 */
As a nit - please use enum {} instead for the above macros.
> + 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)
> {
> int ret;
> struct iovec iov;
> @@ -151,6 +157,8 @@ read_msg(int fd, char *buf, int buflen, int *fds, int
> fds_num)
> iov.iov_base = buf;
> iov.iov_len = buflen;
>
> + msgh.msg_name = s;
> + msgh.msg_namelen = sizeof(*s);
> msgh.msg_iov = &iov;
> msgh.msg_iovlen = 1;
> msgh.msg_control = control;
> @@ -181,7 +189,7 @@ read_msg(int fd, char *buf, int buflen, int *fds, int
> fds_num)
> }
>
> static int
> -process_msg(struct mp_msghdr *hdr, int len, int fds[])
> +process_msg(struct mp_msghdr *hdr, int len, int fds[], struct sockaddr_un *s)
> {
> int ret;
> int params_len;
> @@ -199,10 +207,10 @@ process_msg(struct mp_msghdr *hdr, int len, int fds[])
> }
>
> params_len = len - sizeof(struct mp_msghdr);
> - ret = entry->action(hdr->params, params_len, fds, hdr->fds_num);
> + ret = entry->action(hdr->params, params_len,
> + fds, hdr->fds_num, s->sun_path);
> pthread_mutex_unlock(&mp_mutex_action);
> return ret;
> -
> }
>
> static void *
> @@ -211,11 +219,12 @@ mp_handle(void *arg __rte_unused)
> int len;
> int fds[SCM_MAX_FD];
> char buf[MAX_MSG_LENGTH];
> + struct sockaddr_un sa;
>
> while (1) {
> - len = read_msg(mp_fd, buf, MAX_MSG_LENGTH, fds, SCM_MAX_FD);
> + len = read_msg(mp_fd, buf, MAX_MSG_LENGTH, fds, SCM_MAX_FD,
> &sa);
> if (len > 0)
> - process_msg((struct mp_msghdr *)buf, len, fds);
> + process_msg((struct mp_msghdr *)buf, len, fds, &sa);
> }
>
> return NULL;
> @@ -255,7 +264,8 @@ static int
> mp_primary_proc(const void *params,
> int len __rte_unused,
> int fds[] __rte_unused,
> - int fds_num __rte_unused)
> + int fds_num __rte_unused,
> + const void *peer __rte_unused)
> {
> const struct proc_request *r = (const struct proc_request *)params;
>
> @@ -362,7 +372,8 @@ rte_eal_mp_channel_init(void)
> }
>
> static inline struct mp_msghdr *
> -format_msg(const char *act_name, const void *p, int len_params, int fds_num)
> +format_msg(const char *act_name, const void *p,
> + int len_params, int fds_num, int type)
> {
> int len_msg;
> struct mp_msghdr *msg;
> @@ -384,6 +395,7 @@ format_msg(const char *act_name, const void *p, int
> len_params, int fds_num)
> strcpy(msg->action_name, act_name);
> msg->fds_num = fds_num;
> msg->len_params = len_params;
> + msg->type = type;
> memcpy(msg->params, p, len_params);
> return msg;
> }
> @@ -455,7 +467,9 @@ mp_send(const char *action_name,
> const void *params,
> int len_params,
> int fds[],
> - int fds_num)
> + int fds_num,
> + int type,
> + const void *peer)
> {
> int i;
> int n = 0;
> @@ -468,7 +482,7 @@ mp_send(const char *action_name,
> return 0;
> }
>
> - msg = format_msg(action_name, params, len_params, fds_num);
> + msg = format_msg(action_name, params, len_params, fds_num, type);
> if (msg == NULL)
> return 0;
>
> @@ -477,6 +491,11 @@ mp_send(const char *action_name,
> return 0;
> }
>
> + if (peer) {
> + n += send_msg(sockfd, peer, msg, fds);
> + goto ret;
> + }
> +
> if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
> /* broadcast to all secondaries */
> for (i = 0; i < MAX_SECONDARY_PROCS; ++i) {
> @@ -488,6 +507,7 @@ mp_send(const char *action_name,
> } else
> n += send_msg(sockfd, eal_mp_unix_path(), msg, fds);
>
> +ret:
> free(msg);
> close(sockfd);
> return n;
> @@ -501,5 +521,107 @@ rte_eal_mp_sendmsg(const char *action_name,
> int fds_num)
> {
> RTE_LOG(DEBUG, EAL, "sendmsg: %s\n", action_name);
> - return mp_send(action_name, params, len_params, fds, fds_num);
> + 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)
> +{
> + 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;
> + 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)
> + 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;
> + }
> +
> + ret = send_msg(sockfd, mp_sec_sockets[j], req, fds);
> + } else
> + ret = send_msg(sockfd, eal_mp_unix_path(), req, fds);
> +
> + if (ret == 0) {
> + RTE_LOG(ERR, EAL, "failed to send request: %s\n", action_name);
> + ret = -1;
> + goto free_and_ret;
> + }
> +
> + ret = read_msg(sockfd, buf, MAX_MSG_LENGTH, fds, fds_out, NULL);
> + if (ret > 0) {
> + hdr = (struct mp_msghdr *)buf;
> + if (hdr->len_params == len_p)
> + memcpy(params, hdr->params, len_p);
> + else {
> + RTE_LOG(ERR, EAL, "invalid reply\n");
> + ret = 0;
> + }
> + }
> +
> +free_and_ret:
> + free(req);
> + close(sockfd);
> + pthread_mutex_unlock(&mp_mutex_request);
> + return ret;
> +}
> +
> +int
> +rte_eal_mp_reply(const char *action_name,
> + const void *params,
> + int len_p,
> + int fds[],
> + int fds_in,
> + const void *peer)
> +{
> + RTE_LOG(DEBUG, EAL, "reply: %s\n", action_name);
> + if (peer == NULL) {
> + RTE_LOG(ERR, EAL, "peer is not specified\n");
> + return 0;
> + }
> + return mp_send(action_name, params, len_p, fds, fds_in, MP_REP, peer);
> }
> diff --git a/lib/librte_eal/common/include/rte_eal.h
> b/lib/librte_eal/common/include/rte_eal.h
> index 9884c0b..2690a77 100644
> --- a/lib/librte_eal/common/include/rte_eal.h
> +++ b/lib/librte_eal/common/include/rte_eal.h
> @@ -192,7 +192,7 @@ int rte_eal_primary_proc_alive(const char
> *config_file_path);
> * this function typedef to register action for coming messages.
> */
> typedef int (*rte_eal_mp_t)(const void *params, int len,
> - int fds[], int fds_num);
> + int fds[], int fds_num, const void *peer);
>
> /**
> * Register an action function for primary/secondary communication.
> @@ -245,7 +245,7 @@ void rte_eal_mp_action_unregister(const char *name);
> * The fds argument is an array of fds sent with sendmsg.
> *
> * @param fds_num
> - * The fds_num argument is number of fds to be sent with sendmsg.
> + * The number of fds to be sent with sendmsg.
> *
> * @return
> * - Returns the number of messages being sent successfully.
> @@ -255,6 +255,75 @@ rte_eal_mp_sendmsg(const char *action_name, const void
> *params,
> int len_params, int fds[], int fds_num);
>
> /**
> + * Send a request to the peer process and expect a reply.
> + *
> + * This function sends a request message to the peer process, and will
> + * block until receiving reply message from the peer process. Note:
> + * this does not work for the primary process sending requests to its
> + * multiple (>1) secondary processes.
> + *
> + * @param action_name
> + * The action_name argument is used to identify which action will be used.
> + *
> + * @param params
> + * The params argument contains the customized message; as the reply is
> + * received, the replied params will be copied to this pointer.
> + *
> + * @param len_p
> + * The length of the customized message.
> + *
> + * @param fds
> + * The fds argument is an array of fds sent with sendmsg; as the reply
> + * is received, the replied fds will be copied into this array.
> + *
> + * @param fds_in
> + * The number of fds to be sent.
> + *
> + * @param fds_out
> + * The number of fds to be received.
> + *
> + * @return
> + * - (1) on success;
> + * - (0) on sending request successfully but no valid reply received.
> + * - (<0) on failing to sending request.
> + */
> +int
> +rte_eal_mp_request(const char *action_name, void *params,
> + int len_p, int fds[], int fds_in, int fds_out);
> +
> +/**
> + * Send a reply to the peer process.
> + *
> + * This function will send a reply message in response to a request message
> + * received previously.
> + *
> + * @param action_name
> + * The action_name argument is used to identify which action will be used.
> + *
> + * @param params
> + * The params argument contains the customized message.
> + *
> + * @param len_p
> + * The length of the customized message.
> + *
> + * @param fds
> + * The fds argument is an array of fds sent with sendmsg.
> + *
> + * @param fds_in
> + * The number of fds to be sent with sendmsg.
> + *
> + * @param peer
> + * The fds_num argument is number of fds to be sent with sendmsg.
> + *
> + * @return
> + * - (1) on success;
> + * - (0) on failure.
> + */
> +int
> +rte_eal_mp_reply(const char *action_name, const void *params,
> + int len_p, int fds[], int fds_in, const void *peer);
> +
> +/**
> * Usage function typedef used by the application usage function.
> *
> * Use this function typedef to define and call
> rte_set_application_usage_hook()
> diff --git a/lib/librte_eal/rte_eal_version.map
> b/lib/librte_eal/rte_eal_version.map
> index 5dacde5..068ac0b 100644
> --- a/lib/librte_eal/rte_eal_version.map
> +++ b/lib/librte_eal/rte_eal_version.map
> @@ -243,5 +243,7 @@ DPDK_18.02 {
> rte_eal_mp_action_register;
> rte_eal_mp_action_unregister;
> rte_eal_mp_sendmsg;
> + rte_eal_mp_request;
> + rte_eal_mp_reply;
>
> } DPDK_17.11;
> --
> 2.7.4
