diff --git a/lib/netlink-socket.c b/lib/netlink-socket.c index b5eac0f5f..375772f5e 100644 --- a/lib/netlink-socket.c +++ b/lib/netlink-socket.c @@ -31,6 +31,7 @@ #include "ofpbuf.h" #include "ovs-thread.h" #include "poll-loop.h" +#include "seq.h" #include "socket-util.h" #include "util.h" #include "vlog.h" @@ -690,43 +691,18 @@ nl_sock_drain(struct nl_sock *sock) void nl_dump_start(struct nl_dump *dump, int protocol, const struct ofpbuf *request) { - dump->status = nl_pool_alloc(protocol, &dump->sock); - if (dump->status) { + int status = nl_pool_alloc(protocol, &dump->sock); + + if (status) { return; } nl_msg_nlmsghdr(request)->nlmsg_flags |= NLM_F_DUMP | NLM_F_ACK; - dump->status = nl_sock_send__(dump->sock, request, - nl_sock_allocate_seq(dump->sock, 1), true); + status = nl_sock_send__(dump->sock, request, + nl_sock_allocate_seq(dump->sock, 1), true); + atomic_init(&dump->status, status << 1); dump->nl_seq = nl_msg_nlmsghdr(request)->nlmsg_seq; -} - -/* Helper function for nl_dump_next(). */ -static int -nl_dump_recv(struct nl_dump *dump, struct ofpbuf *buffer) -{ - struct nlmsghdr *nlmsghdr; - int retval; - - retval = nl_sock_recv__(dump->sock, buffer, true); - if (retval) { - return retval == EINTR ? EAGAIN : retval; - } - - nlmsghdr = nl_msg_nlmsghdr(buffer); - if (dump->nl_seq != nlmsghdr->nlmsg_seq) { - VLOG_DBG_RL(&rl, "ignoring seq %#"PRIx32" != expected %#"PRIx32, - nlmsghdr->nlmsg_seq, dump->nl_seq); - return EAGAIN; - } - - if (nl_msg_nlmsgerr(buffer, &retval)) { - VLOG_INFO_RL(&rl, "netlink dump request error (%s)", - ovs_strerror(retval)); - return retval && retval != EAGAIN ? retval : EPROTO; - } - - return 0; + dump->status_seq = seq_create(); } /* Attempts to retrieve another reply from 'dump' into 'buffer'. 'dump' must @@ -742,40 +718,83 @@ nl_dump_recv(struct nl_dump *dump, struct ofpbuf *buffer) * to 0. Failure might indicate an actual error or merely the end of replies. * An error status for the entire dump operation is provided when it is * completed by calling nl_dump_done(). + * + * Multiple threads may call this function, passing the same nl_dump, however + * each must provide independent buffers. This function may cache multiple + * replies in the buffer, and these will be processed before more replies are + * fetched. When this function returns false, other threads may continue to + * process replies in their buffers, but they will not fetch more replies. */ bool nl_dump_next(struct nl_dump *dump, struct ofpbuf *reply, struct ofpbuf *buffer) { struct nlmsghdr *nlmsghdr; + int error = 0; reply->data = NULL; reply->size = 0; - if (dump->status) { - return false; - } + /* If 'buffer' is empty, fetch another batch of nlmsgs. */ while (!buffer->size) { - int retval = nl_dump_recv(dump, buffer); + unsigned int status; + int retval, seq; + + seq = seq_read(dump->status_seq); + atomic_read(&dump->status, &status); + if (status) { + return false; + } + + retval = nl_sock_recv__(dump->sock, buffer, false); if (retval) { ofpbuf_clear(buffer); - if (retval != EAGAIN) { - dump->status = retval; - return false; + if (retval == EAGAIN) { + nl_sock_wait(dump->sock, POLLIN); + seq_wait(dump->status_seq, seq); + poll_block(); + continue; + } else { + error = retval; + goto exit; } } + + nlmsghdr = nl_msg_nlmsghdr(buffer); + if (dump->nl_seq != nlmsghdr->nlmsg_seq) { + VLOG_DBG_RL(&rl, "ignoring seq %#"PRIx32" != expected %#"PRIx32, + nlmsghdr->nlmsg_seq, dump->nl_seq); + ofpbuf_clear(buffer); + continue; + } + + if (nl_msg_nlmsgerr(buffer, &retval) && retval) { + VLOG_INFO_RL(&rl, "netlink dump request error (%s)", + ovs_strerror(retval)); + error = retval == EAGAIN ? EPROTO : retval; + ofpbuf_clear(buffer); + goto exit; + } } + /* Fetch the next nlmsg in the current batch. */ nlmsghdr = nl_msg_next(buffer, reply); if (!nlmsghdr) { VLOG_WARN_RL(&rl, "netlink dump reply contains message fragment"); - dump->status = EPROTO; - return false; + error = EPROTO; } else if (nlmsghdr->nlmsg_type == NLMSG_DONE) { - dump->status = EOF; - return false; + error = EOF; } - return true; +exit: + if (error == EOF) { + unsigned int old; + atomic_or(&dump->status, 1, &old); + seq_change(dump->status_seq); + } else if (error) { + atomic_store(&dump->status, error << 1); + seq_change(dump->status_seq); + } + return !error; } /* Completes Netlink dump operation 'dump', which must have been initialized @@ -784,23 +803,29 @@ nl_dump_next(struct nl_dump *dump, struct ofpbuf *reply, struct ofpbuf *buffer) int nl_dump_done(struct nl_dump *dump) { - uint64_t tmp_reply_stub[NL_DUMP_BUFSIZE / 8]; - struct ofpbuf buf; + int status; /* Drain any remaining messages that the client didn't read. Otherwise the * kernel will continue to queue them up and waste buffer space. * * XXX We could just destroy and discard the socket in this case. */ - ofpbuf_use_stub(&buf, tmp_reply_stub, sizeof tmp_reply_stub); - while (!dump->status) { - struct ofpbuf reply; - if (!nl_dump_next(dump, &reply, &buf)) { - ovs_assert(dump->status); + atomic_read(&dump->status, &status); + if (!status) { + uint64_t tmp_reply_stub[NL_DUMP_BUFSIZE / 8]; + struct ofpbuf reply, buf; + + ofpbuf_use_stub(&buf, tmp_reply_stub, sizeof tmp_reply_stub); + while (nl_dump_next(dump, &reply, &buf)) { + /* Nothing to do. */ } + atomic_read(&dump->status, &status); + ovs_assert(status); + ofpbuf_uninit(&buf); } + atomic_destroy(&dump->status); nl_pool_release(dump->sock); - ofpbuf_uninit(&buf); - return dump->status == EOF ? 0 : dump->status; + seq_destroy(dump->status_seq); + return status >> 1; } /* Causes poll_block() to wake up when any of the specified 'events' (which is diff --git a/lib/netlink-socket.h b/lib/netlink-socket.h index 211c13283..dd3240907 100644 --- a/lib/netlink-socket.h +++ b/lib/netlink-socket.h @@ -35,13 +35,23 @@ * Thread-safety * ============= * - * Only a single thread may use a given nl_sock or nl_dump at one time. + * Most of the netlink functions are not fully thread-safe: Only a single + * thread may use a given nl_sock or nl_dump at one time. The exceptions are: + * + * - nl_sock_recv() is conditionally thread-safe: it may be called from + * different threads with the same nl_sock, but each caller must provide + * an independent receive buffer. + * + * - nl_dump_next() is conditionally thread-safe: it may be called from + * different threads with the same nl_dump, but each caller must provide + * independent buffers. */ #include #include #include #include "ofpbuf.h" +#include "ovs-atomic.h" struct nl_sock; @@ -101,7 +111,9 @@ void nl_transact_multiple(int protocol, struct nl_transaction **, size_t n); struct nl_dump { struct nl_sock *sock; /* Socket being dumped. */ uint32_t nl_seq; /* Expected nlmsg_seq for replies. */ - int status; /* 0=OK, EOF=done, or positive errno value. */ + atomic_uint status; /* Low bit set if we read final message. + * Other bits hold an errno (0 for success). */ + struct seq *status_seq; /* Tracks changes to the above 'status'. */ }; void nl_dump_start(struct nl_dump *, int protocol,