ntp: check timestamping configuration when SIOCSHWTSTAMP fails

With future kernels it may be possible to get, but not set, the HW
timestamping configuration on some specific interfaces like macvlan in
containers. This would require the admin to configure the timestamping
before starting chronyd.

If SIOCSHWTSTAMP failed on an interface, try SIOCGHWTSTAMP to check if
the current configuration matches the expected configuration and allow
the interface to be used for HW timestamping.

diff --git a/ntp_io_linux.c b/ntp_io_linux.c
index eb4a3a83a3baff14956ccf0e43bc6b7f9658ee39..374ac5cf5bd20eaad917c4ee16338148e0777718 100644 (file)
--- a/ntp_io_linux.c
+++ b/ntp_io_linux.c
@@ -123,7 +123,7 @@ add_interface(CNF_HwTsInterface *conf_iface)
   struct ethtool_ts_info ts_info;
   struct hwtstamp_config ts_config;
   struct ifreq req;
-  int sock_fd, if_index, phc_fd, req_hwts_flags;
+  int sock_fd, if_index, phc_fd, req_hwts_flags, rx_filter;
   unsigned int i;
   struct Interface *iface;
 
@@ -177,40 +177,51 @@ add_interface(CNF_HwTsInterface *conf_iface)
     return 0;
   }
 
-  ts_config.flags = 0;
-  ts_config.tx_type = HWTSTAMP_TX_ON;
-
   switch (conf_iface->rxfilter) {
     case CNF_HWTS_RXFILTER_ANY:
 #ifdef HAVE_LINUX_TIMESTAMPING_RXFILTER_NTP
       if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_NTP_ALL))
-        ts_config.rx_filter = HWTSTAMP_FILTER_NTP_ALL;
+        rx_filter = HWTSTAMP_FILTER_NTP_ALL;
       else
 #endif
       if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_ALL))
-        ts_config.rx_filter = HWTSTAMP_FILTER_ALL;
+        rx_filter = HWTSTAMP_FILTER_ALL;
       else
-        ts_config.rx_filter = HWTSTAMP_FILTER_NONE;
+        rx_filter = HWTSTAMP_FILTER_NONE;
       break;
     case CNF_HWTS_RXFILTER_NONE:
-      ts_config.rx_filter = HWTSTAMP_FILTER_NONE;
+      rx_filter = HWTSTAMP_FILTER_NONE;
       break;
 #ifdef HAVE_LINUX_TIMESTAMPING_RXFILTER_NTP
     case CNF_HWTS_RXFILTER_NTP:
-      ts_config.rx_filter = HWTSTAMP_FILTER_NTP_ALL;
+      rx_filter = HWTSTAMP_FILTER_NTP_ALL;
       break;
 #endif
     default:
-      ts_config.rx_filter = HWTSTAMP_FILTER_ALL;
+      rx_filter = HWTSTAMP_FILTER_ALL;
       break;
   }
 
+  ts_config.flags = 0;
+  ts_config.tx_type = HWTSTAMP_TX_ON;
+  ts_config.rx_filter = rx_filter;
   req.ifr_data = (char *)&ts_config;
 
   if (ioctl(sock_fd, SIOCSHWTSTAMP, &req)) {
     DEBUG_LOG("ioctl(%s) failed : %s", "SIOCSHWTSTAMP", strerror(errno));
-    close(sock_fd);
-    return 0;
+
+    /* Check the current timestamping configuration in case this interface
+       allows only reading of the configuration and it was already configured
+       as requested */
+    req.ifr_data = (char *)&ts_config;
+#ifdef SIOCGHWTSTAMP
+    if (ioctl(sock_fd, SIOCGHWTSTAMP, &req) ||
+        ts_config.tx_type != HWTSTAMP_TX_ON || ts_config.rx_filter != rx_filter)
+#endif
+    {
+      close(sock_fd);
+      return 0;
+    }
   }
 
   close(sock_fd);