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

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).

diff --git a/ntp_core.c b/ntp_core.c
index 73519a318de83ecc61aa37e10977ca5c455bc037..22cab439bf55ad66f73b48dc5b372151843542b0 100644 (file)
--- a/ntp_core.c
+++ b/ntp_core.c
@@ -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);
   }

diff --git a/ntp_io.c b/ntp_io.c
index deb8e25ad61840e072db401d98a99d4aa51be270..fce7b1772478c460a1968497966783b432b9b845 100644 (file)
--- a/ntp_io.c
+++ b/ntp_io.c
@@ -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)
 {

diff --git a/ntp_io.h b/ntp_io.h
index 19ffeed661039d8aba5b10ef707b495da2ab977d..427bd966ea95f35593c874382cb3e2f48f58e2f1 100644 (file)
--- a/ntp_io.h
+++ b/ntp_io.h
@@ -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);
 

diff --git a/ntp_io_linux.c b/ntp_io_linux.c
index 6988a2863bcb859d0dff0c9e9ac4162d8ccfea7b..8f93f599dd8ca8eeefff81a8056c631c9639af6d 100644 (file)
--- a/ntp_io_linux.c
+++ b/ntp_io_linux.c
@@ -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)
 {

diff --git a/ntp_io_linux.h b/ntp_io_linux.h
index 089d4a12ac2435bf3d9ac2de0aada2a18f0e6b9e..79788895c782e54d52f9652f76befea7bb6d5138 100644 (file)
--- a/ntp_io_linux.h
+++ b/ntp_io_linux.h
@@ -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,

diff --git a/test/unit/ntp_core.c b/test/unit/ntp_core.c
index 7d6498674a6add87fb151c43369399352fe866c2..08a153260751bfb2e2532bdfb6f769c1f7ee56d0 100644 (file)
--- a/test/unit/ntp_core.c
+++ b/test/unit/ntp_core.c
@@ -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;
   }
 }