diff options
Diffstat (limited to 'ntp_io_linux.c')
| -rw-r--r-- | ntp_io_linux.c | 157 |
1 files changed, 155 insertions, 2 deletions
diff --git a/ntp_io_linux.c b/ntp_io_linux.c index 00caed0..df944d7 100644 --- a/ntp_io_linux.c +++ b/ntp_io_linux.c @@ -94,6 +94,27 @@ static int ts_tx_flags; /* Flag indicating the socket options can't be changed in control messages */ static int permanent_ts_options; +/* When sending client requests to a close and fast server, it is possible that + a response will be received before the HW transmit timestamp of the request + itself. To avoid processing of the response without the HW timestamp, we + monitor events returned by select() and suspend reading of packets from the + receive queue for up to 200 microseconds. As the requests are normally + separated by at least 200 milliseconds, it is sufficient to monitor and + suspend one socket at a time. */ +static int monitored_socket; +static int suspended_socket; +static SCH_TimeoutID resume_timeout_id; + +#define RESUME_TIMEOUT 200.0e-6 + +/* Unbound socket keeping the kernel RX timestamping permanently enabled + in order to avoid a race condition between receiving a server response + and the kernel actually starting to timestamp received packets after + enabling the timestamping and sending a request */ +static int dummy_rxts_socket; + +#define INVALID_SOCK_FD -3 + /* ================================================== */ static int @@ -252,7 +273,7 @@ update_interface_speed(struct Interface *iface) { struct ethtool_cmd cmd; struct ifreq req; - int sock_fd; + int sock_fd, link_speed; sock_fd = socket(AF_INET, SOCK_DGRAM, 0); if (sock_fd < 0) @@ -273,7 +294,12 @@ update_interface_speed(struct Interface *iface) close(sock_fd); - iface->link_speed = ethtool_cmd_speed(&cmd); + link_speed = ethtool_cmd_speed(&cmd); + + if (iface->link_speed != link_speed) { + iface->link_speed = link_speed; + DEBUG_LOG("Updated speed of %s to %d Mb/s", iface->name, link_speed); + } } /* ================================================== */ @@ -301,6 +327,29 @@ check_timestamping_option(int option) /* ================================================== */ +static int +open_dummy_socket(void) +{ + int sock_fd, events = 0; + + if ((sock_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 +#ifdef FEAT_IPV6 + && (sock_fd = socket(AF_INET6, SOCK_DGRAM, 0)) < 0 +#endif + ) + return INVALID_SOCK_FD; + + if (!NIO_Linux_SetTimestampSocketOptions(sock_fd, 1, &events)) { + close(sock_fd); + return INVALID_SOCK_FD; + } + + UTI_FdSetCloexec(sock_fd); + return sock_fd; +} + +/* ================================================== */ + void NIO_Linux_Initialise(void) { @@ -350,6 +399,10 @@ NIO_Linux_Initialise(void) /* Kernels before 4.7 ignore timestamping flags set in control messages */ permanent_ts_options = !SYS_Linux_CheckKernelVersion(4, 7); + + monitored_socket = INVALID_SOCK_FD; + suspended_socket = INVALID_SOCK_FD; + dummy_rxts_socket = INVALID_SOCK_FD; } /* ================================================== */ @@ -360,6 +413,9 @@ NIO_Linux_Finalise(void) struct Interface *iface; unsigned int i; + if (dummy_rxts_socket != INVALID_SOCK_FD) + close(dummy_rxts_socket); + for (i = 0; i < ARR_GetSize(interfaces); i++) { iface = ARR_GetElement(interfaces, i); HCL_DestroyInstance(iface->clock); @@ -406,6 +462,73 @@ NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events) /* ================================================== */ +static void +resume_socket(int sock_fd) +{ + if (monitored_socket == sock_fd) + monitored_socket = INVALID_SOCK_FD; + + if (sock_fd == INVALID_SOCK_FD || sock_fd != suspended_socket) + return; + + suspended_socket = INVALID_SOCK_FD; + + SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_INPUT, 1); + + DEBUG_LOG("Resumed RX processing %s timeout fd=%d", + resume_timeout_id ? "before" : "on", sock_fd); + + if (resume_timeout_id) { + SCH_RemoveTimeout(resume_timeout_id); + resume_timeout_id = 0; + } +} + +/* ================================================== */ + +static void +resume_timeout(void *arg) +{ + resume_timeout_id = 0; + resume_socket(suspended_socket); +} + +/* ================================================== */ + +static void +suspend_socket(int sock_fd) +{ + resume_socket(suspended_socket); + + suspended_socket = sock_fd; + + SCH_SetFileHandlerEvent(suspended_socket, SCH_FILE_INPUT, 0); + resume_timeout_id = SCH_AddTimeoutByDelay(RESUME_TIMEOUT, resume_timeout, NULL); + + DEBUG_LOG("Suspended RX processing fd=%d", sock_fd); +} + +/* ================================================== */ + +int +NIO_Linux_ProcessEvent(int sock_fd, int event) +{ + if (sock_fd != monitored_socket) + return 0; + + if (event == SCH_FILE_INPUT) { + suspend_socket(monitored_socket); + monitored_socket = INVALID_SOCK_FD; + + /* Don't process the message yet */ + return 1; + } + + return 0; +} + +/* ================================================== */ + static struct Interface * get_interface(int if_index) { @@ -614,6 +737,11 @@ NIO_Linux_ProcessMessage(NTP_Remote_Address *remote_addr, NTP_Local_Address *loc } else { DEBUG_LOG("HW clock not found for interface %d", ts_if_index); } + + /* If a HW transmit timestamp was received, resume processing + of non-error messages on this socket */ + if (is_tx) + resume_socket(local_addr->sock_fd); } if (local_ts->source == NTP_TS_DAEMON && !UTI_IsZeroTimespec(&ts3.ts[0]) && @@ -638,6 +766,14 @@ NIO_Linux_ProcessMessage(NTP_Remote_Address *remote_addr, NTP_Local_Address *loc } } + /* If the kernel is slow with enabling RX timestamping, open a dummy + socket to keep the kernel RX timestamping permanently enabled */ + if (!is_tx && local_ts->source == NTP_TS_DAEMON && ts_flags) { + DEBUG_LOG("Missing kernel RX timestamp"); + if (dummy_rxts_socket == INVALID_SOCK_FD) + dummy_rxts_socket = open_dummy_socket(); + } + /* Return the message if it's not received from the error queue */ if (!is_tx) return 0; @@ -682,6 +818,15 @@ NIO_Linux_RequestTxTimestamp(struct msghdr *msg, int cmsglen, int sock_fd) { struct cmsghdr *cmsg; + if (!ts_flags) + return cmsglen; + + /* If a HW transmit timestamp is requested on a client socket, monitor + events on the socket in order to avoid processing of a fast response + without the HW timestamp of the request */ + if (ts_tx_flags & SOF_TIMESTAMPING_TX_HARDWARE && !NIO_IsServerSocket(sock_fd)) + monitored_socket = sock_fd; + /* Check if TX timestamping is disabled on this socket */ if (permanent_ts_options || !NIO_IsServerSocket(sock_fd)) return cmsglen; @@ -701,3 +846,11 @@ NIO_Linux_RequestTxTimestamp(struct msghdr *msg, int cmsglen, int sock_fd) return cmsglen; } + +/* ================================================== */ + +void +NIO_Linux_NotifySocketClosing(int sock_fd) +{ + resume_socket(sock_fd); +} |