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/* Copyright (c) 2012, 2013 Nicira, Inc.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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#include <sys/socket.h>
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#include <sys/types.h>
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#include "command-line.h"
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#include "poll-loop.h"
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#include "socket-util.h"
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VLOG_DEFINE_THIS_MODULE(worker);
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/* ovs_assert() logs the assertion message and logging sometimes goes through a
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* worker, so using ovs_assert() in this source file could cause recursion. */
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#define ovs_assert use_assert_instead_of_ovs_assert_in_this_module
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/* Header for an RPC request. */
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struct worker_request {
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size_t request_len; /* Length of the payload in bytes. */
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worker_request_func *request_cb; /* Function to call in worker process. */
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worker_reply_func *reply_cb; /* Function to call in main process. */
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void *reply_aux; /* Auxiliary data for 'reply_cb'. */
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/* Header for an RPC reply. */
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size_t reply_len; /* Length of the payload in bytes. */
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worker_reply_func *reply_cb; /* Function to call in main process. */
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void *reply_aux; /* Auxiliary data for 'reply_cb'. */
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/* Receive buffer for a RPC request or reply. */
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struct ofpbuf header; /* Header data. */
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int fds[SOUTIL_MAX_FDS]; /* File descriptors. */
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struct ofpbuf payload; /* Payload data. */
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static int client_sock = -1;
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static struct rxbuf client_rx;
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static void rxbuf_init(struct rxbuf *);
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static void rxbuf_clear(struct rxbuf *);
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static int rxbuf_run(struct rxbuf *, int sock, size_t header_len);
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static struct iovec *prefix_iov(void *data, size_t len,
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const struct iovec *iovs, size_t n_iovs);
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static void worker_broke(void);
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static void worker_main(int fd) NO_RETURN;
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/* Starts a worker process as a subprocess of the current process. Currently
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* only a single worker process is supported, so this function may only be
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* The client should call worker_run() and worker_wait() from its main loop.
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* Call this function between daemonize_start() and daemonize_complete(). */
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assert(client_sock < 0);
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/* Create non-blocking socket pair. */
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xsocketpair(AF_UNIX, SOCK_STREAM, 0, work_fds);
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xset_nonblocking(work_fds[0]);
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xset_nonblocking(work_fds[1]);
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/* Don't let the worker process own the responsibility to delete
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* the pidfile. Register it again after the fork. */
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remove_pidfile_from_unlink();
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if (!fork_and_clean_up()) {
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/* In child (worker) process. */
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daemonize_post_detach();
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worker_main(work_fds[1]);
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/* In parent (main) process. */
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add_pidfile_to_unlink();
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client_sock = work_fds[0];
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rxbuf_init(&client_rx);
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/* Returns true if this process has started a worker and the worker is not
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* known to have malfunctioned. */
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worker_is_running(void)
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return client_sock >= 0;
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/* If a worker process was started, processes RPC replies from it, calling the
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* registered 'reply_cb' callbacks.
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* If the worker process died or malfunctioned, aborts. */
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if (worker_is_running()) {
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error = rxbuf_run(&client_rx, client_sock,
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sizeof(struct worker_reply));
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struct worker_reply *reply = client_rx.header.data;
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reply->reply_cb(&client_rx.payload, client_rx.fds,
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client_rx.n_fds, reply->reply_aux);
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rxbuf_clear(&client_rx);
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} else if (error != EAGAIN) {
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VLOG_ABORT("receive from worker failed (%s)",
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ovs_retval_to_string(error));
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/* Causes the poll loop to wake up if we need to process RPC replies. */
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if (worker_is_running()) {
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poll_fd_wait(client_sock, POLLIN);
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/* Interface for main process to interact with the worker. */
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/* Sends an RPC request to the worker process. The worker process will call
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* 'request_cb' passing the 'size' (zero or more) bytes of data in 'data' as
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* arguments as well as the 'n_fds' (SOUTIL_MAX_FDS or fewer) file descriptors
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* If and only if 'reply_cb' is nonnull, 'request_cb' must call worker_reply()
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* or worker_reply_iovec() with a reply. The main process will later call
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* 'reply_cb' with the reply data (if any) and file descriptors (if any).
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* 'request_cb' receives copies (as if by dup()) of the file descriptors in
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* fds[]. 'request_cb' takes ownership of these copies, and the caller of
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* worker_request() retains its ownership of the originals.
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* This function may block until the RPC request has been sent (if the socket
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* buffer fills up) but it does not wait for the reply (if any). If this
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* function blocks, it may invoke reply callbacks for previous requests.
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* The worker process executes RPC requests in strict order of submission and
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* runs each request to completion before beginning the next request. The main
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* process invokes reply callbacks in strict order of request submission. */
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worker_request(const void *data, size_t size,
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const int fds[], size_t n_fds,
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worker_request_func *request_cb,
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worker_reply_func *reply_cb, void *aux)
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iov.iov_base = (void *) data;
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worker_request_iovec(&iov, 1, fds, n_fds, request_cb, reply_cb, aux);
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worker_request_iovec(NULL, 0, fds, n_fds, request_cb, reply_cb, aux);
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worker_send_iovec(const struct iovec iovs[], size_t n_iovs,
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const int fds[], size_t n_fds)
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/* Try to send the rest of the request. */
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error = send_iovec_and_fds_fully(client_sock, iovs, n_iovs,
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fds, n_fds, sent, &sent);
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if (error != EAGAIN) {
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/* Process replies to avoid deadlock. */
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/* Wait for 'client_sock' to become ready before trying again. We
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* can't use poll_block() because it sometimes calls into vlog, which
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* calls indirectly into worker_send_iovec(). To be usable here,
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* poll_block() would therefore need to be reentrant, but it isn't
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* (calling it recursively causes memory corruption and an eventual
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pfd.fd = client_sock;
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pfd.events = POLLIN | POLLOUT;
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error = poll(&pfd, 1, -1) < 0 ? errno : 0;
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} while (error == EINTR);
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VLOG_ABORT("poll failed (%s)", strerror(error));
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/* Same as worker_request() except that the data to send is specified as an
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* array of iovecs. */
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worker_request_iovec(const struct iovec iovs[], size_t n_iovs,
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const int fds[], size_t n_fds,
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worker_request_func *request_cb,
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worker_reply_func *reply_cb, void *aux)
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static bool recursing = false;
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struct worker_request rq;
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struct iovec *all_iovs;
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assert(worker_is_running());
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rq.request_len = iovec_len(iovs, n_iovs);
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rq.request_cb = request_cb;
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rq.reply_cb = reply_cb;
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all_iovs = prefix_iov(&rq, sizeof rq, iovs, n_iovs);
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error = worker_send_iovec(all_iovs, n_iovs + 1, fds, n_fds);
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VLOG_ABORT("send failed (%s)", strerror(error));
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/* Closes the client socket, if any, so that worker_is_running() will return
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* The client does this just before aborting if the worker process dies or
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* malfunctions, to prevent the logging subsystem from trying to use the
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* worker to log the failure. */
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if (client_sock >= 0) {
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/* Interfaces for RPC implementations (running in the worker process). */
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static int server_sock = -1;
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static bool expect_reply;
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static struct worker_request request;
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/* When a call to worker_request() or worker_request_iovec() provides a
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* 'reply_cb' callback, the 'request_cb' implementation must call this function
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* to send its reply. The main process will call 'reply_cb' passing the
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* 'size' (zero or more) bytes of data in 'data' as arguments as well as the
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* 'n_fds' (SOUTIL_MAX_FDS or fewer) file descriptors in 'fds'.
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* If a call to worker_request() or worker_request_iovec() provides no
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* 'reply_cb' callback, the 'request_cb' implementation must not call this
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* 'reply_cb' receives copies (as if by dup()) of the file descriptors in
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* fds[]. 'reply_cb' takes ownership of these copies, and the caller of
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* worker_reply() retains its ownership of the originals.
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* This function blocks until the RPC reply has been sent (if the socket buffer
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* fills up) but it does not wait for the main process to receive or to process
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worker_reply(const void *data, size_t size, const int fds[], size_t n_fds)
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iov.iov_base = (void *) data;
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worker_reply_iovec(&iov, 1, fds, n_fds);
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worker_reply_iovec(NULL, 0, fds, n_fds);
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/* Same as worker_reply() except that the data to send is specified as an array
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worker_reply_iovec(const struct iovec *iovs, size_t n_iovs,
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const int fds[], size_t n_fds)
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struct worker_reply reply;
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struct iovec *all_iovs;
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assert(expect_reply);
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expect_reply = false;
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reply.reply_len = iovec_len(iovs, n_iovs);
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reply.reply_cb = request.reply_cb;
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reply.reply_aux = request.reply_aux;
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all_iovs = prefix_iov(&reply, sizeof reply, iovs, n_iovs);
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error = send_iovec_and_fds_fully_block(server_sock, all_iovs, n_iovs + 1,
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if (error == EPIPE) {
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/* Parent probably died. Continue processing any RPCs still buffered,
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* to avoid missing log messages. */
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VLOG_INFO("send failed (%s)", strerror(error));
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VLOG_FATAL("send failed (%s)", strerror(error));
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subprogram_name = "worker";
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proctitle_set("worker process for pid %lu", (unsigned long int) getppid());
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VLOG_INFO("worker process started");
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error = rxbuf_run(&rx, server_sock, sizeof(struct worker_request));
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request = *(struct worker_request *) rx.header.data;
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expect_reply = request.reply_cb != NULL;
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request.request_cb(&rx.payload, rx.fds, rx.n_fds);
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assert(!expect_reply);
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} else if (error == EOF && !rx.header.size) {
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/* Main process closed the IPC socket. Exit cleanly. */
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} else if (error != EAGAIN) {
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VLOG_FATAL("RPC receive failed (%s)", ovs_retval_to_string(error));
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poll_fd_wait(server_sock, POLLIN);
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VLOG_INFO("worker process exiting");
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rxbuf_init(struct rxbuf *rx)
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ofpbuf_init(&rx->header, 0);
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ofpbuf_init(&rx->payload, 0);
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rxbuf_clear(struct rxbuf *rx)
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ofpbuf_clear(&rx->header);
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ofpbuf_clear(&rx->payload);
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rxbuf_run(struct rxbuf *rx, int sock, size_t header_len)
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if (!rx->header.size) {
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ofpbuf_clear(&rx->header);
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ofpbuf_prealloc_tailroom(&rx->header, header_len);
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retval = recv_data_and_fds(sock, rx->header.data, header_len,
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rx->fds, &rx->n_fds);
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return retval ? -retval : EOF;
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rx->header.size += retval;
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} else if (rx->header.size < header_len) {
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error = read_fully(sock, ofpbuf_tail(&rx->header),
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header_len - rx->header.size, &bytes_read);
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rx->header.size += bytes_read;
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size_t payload_len = *(size_t *) rx->header.data;
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if (rx->payload.size < payload_len) {
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size_t left = payload_len - rx->payload.size;
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ofpbuf_prealloc_tailroom(&rx->payload, left);
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error = read_fully(sock, ofpbuf_tail(&rx->payload), left,
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rx->payload.size += bytes_read;
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static struct iovec *
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prefix_iov(void *data, size_t len, const struct iovec *iovs, size_t n_iovs)
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dst = xmalloc((n_iovs + 1) * sizeof *dst);
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dst[0].iov_base = data;
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dst[0].iov_len = len;
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memcpy(dst + 1, iovs, n_iovs * sizeof *iovs);
added
removed
lib/worker.c
