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ntp: don't require previous HW TX timestamp to wait for another

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Clients sockets are closed immediately after receiving valid response.
Don't wait for the first early HW TX timestamp to enable waiting for
late timestamps. It may take a long time or never come if the HW/driver
is consistently slow. It's a chicken and egg problem.

Instead, simply check if HW timestamping is enabled on at least one
interface. Responses from NTP sources on other interfaces will always be
saved (for 1 millisecond by default).
This commit is contained in:
Miroslav Lichvar 2023-08-08 15:44:25 +02:00
parent 7bc7d00297
commit 3dc9f1ff92
6 changed files with 28 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
ntp_core.c
View file

@ -215,9 +215,6 @@ struct NCR_Instance_Record {
SPF_Instance filter;
int filter_count;
/* Flag indicating HW transmit timestamps are expected */
int had_hw_tx_timestamp;
/* Response waiting for a HW transmit timestamp of the request */
struct SavedResponse *saved_response;
@ -794,8 +791,6 @@ NCR_ResetInstance(NCR_Instance instance)
if (instance->filter)
SPF_DropSamples(instance->filter);
instance->filter_count = 0;
instance->had_hw_tx_timestamp = 0;
}
/* ================================================== */
@ -1966,7 +1961,7 @@ process_response(NCR_Instance inst, int saved, NTP_Local_Address *local_addr,
response to the request, when at least one good response has already been
accepted to avoid incorrectly confirming a tentative source. */
if (valid_packet && synced_packet && !saved && !inst->valid_rx &&
inst->had_hw_tx_timestamp && inst->local_tx.source != NTP_TS_HARDWARE &&
NIO_IsHwTsEnabled() && inst->local_tx.source != NTP_TS_HARDWARE &&
inst->report.total_good_count > 0) {
if (save_response(inst, local_addr, rx_ts, message, info))
return 1;
@ -2692,8 +2687,6 @@ NCR_ProcessTxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
message);
if (tx_ts->source == NTP_TS_HARDWARE) {
inst->had_hw_tx_timestamp = 1;
if (has_saved_response(inst))
process_saved_response(inst);
}

12
ntp_io.c
View file

@ -278,6 +278,18 @@ NIO_Finalise(void)
/* ================================================== */
int
NIO_IsHwTsEnabled(void)
{
#ifdef HAVE_LINUX_TIMESTAMPING
return NIO_Linux_IsHwTsEnabled();
#else
return 0;
#endif
}
/* ================================================== */
int
NIO_OpenClientSocket(NTP_Remote_Address *remote_addr)
{

3
ntp_io.h
View file

@ -39,6 +39,9 @@ extern void NIO_Initialise(void);
/* Function to finalise the module */
extern void NIO_Finalise(void);
/* Function to check if HW timestamping is enabled on any interface */
extern int NIO_IsHwTsEnabled(void);
/* Function to obtain a socket for sending client packets */
extern int NIO_OpenClientSocket(NTP_Remote_Address *remote_addr);

8
ntp_io_linux.c
View file

@ -439,6 +439,14 @@ NIO_Linux_Finalise(void)
/* ================================================== */
int
NIO_Linux_IsHwTsEnabled(void)
{
return ARR_GetSize(interfaces) > 0;
}
/* ================================================== */
int
NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events)
{

2
ntp_io_linux.h
View file

@ -33,6 +33,8 @@ extern void NIO_Linux_Initialise(void);
extern void NIO_Linux_Finalise(void);
extern int NIO_Linux_IsHwTsEnabled(void);
extern int NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events);
extern int NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,

7
test/unit/ntp_core.c
View file

@ -35,6 +35,7 @@ static struct timespec current_time;
static NTP_Packet req_buffer, res_buffer;
static int req_length, res_length;
#define NIO_IsHwTsEnabled() 1
#define NIO_OpenServerSocket(addr) ((addr)->ip_addr.family != IPADDR_UNSPEC ? 100 : 0)
#define NIO_CloseServerSocket(fd) assert(fd == 100)
#define NIO_OpenClientSocket(addr) ((addr)->ip_addr.family != IPADDR_UNSPEC ? 101 : 0)
@ -106,13 +107,9 @@ send_request(NCR_Instance inst, int late_hwts)
}
if (late_hwts) {
inst->had_hw_tx_timestamp = 1;
inst->report.total_good_count++;
} else {
if (random() % 2)
inst->had_hw_tx_timestamp = 0;
else
inst->report.total_good_count = 0;
inst->report.total_good_count = 0;
}
}