Merge pull request #21667 from yuwata/resolve-do-not-re-read-settings-from-networkd-when-unmodified

resolve: do not re-read settings from networkd when link state file is unmodified

src/libsystemd/sd-network/sd-network.c

@@ -37,27 +37,27 @@ static int network_get_string(const char *field, char **ret) {
         return 0;
 }
 
-_public_ int sd_network_get_operational_state(char **state) {
+int sd_network_get_operational_state(char **state) {
         return network_get_string("OPER_STATE", state);
 }
 
-_public_ int sd_network_get_carrier_state(char **state) {
+int sd_network_get_carrier_state(char **state) {
         return network_get_string("CARRIER_STATE", state);
 }
 
-_public_ int sd_network_get_address_state(char **state) {
+int sd_network_get_address_state(char **state) {
         return network_get_string("ADDRESS_STATE", state);
 }
 
-_public_ int sd_network_get_ipv4_address_state(char **state) {
+int sd_network_get_ipv4_address_state(char **state) {
         return network_get_string("IPV4_ADDRESS_STATE", state);
 }
 
-_public_ int sd_network_get_ipv6_address_state(char **state) {
+int sd_network_get_ipv6_address_state(char **state) {
         return network_get_string("IPV6_ADDRESS_STATE", state);
 }
 
-_public_ int sd_network_get_online_state(char **state) {
+int sd_network_get_online_state(char **state) {
         return network_get_string("ONLINE_STATE", state);
 }
 
@@ -90,24 +90,24 @@ static int network_get_strv(const char *key, char ***ret) {
         return r;
 }
 
-_public_ int sd_network_get_dns(char ***ret) {
+int sd_network_get_dns(char ***ret) {
         return network_get_strv("DNS", ret);
 }
 
-_public_ int sd_network_get_ntp(char ***ret) {
+int sd_network_get_ntp(char ***ret) {
         return network_get_strv("NTP", ret);
 }
 
-_public_ int sd_network_get_search_domains(char ***ret) {
+int sd_network_get_search_domains(char ***ret) {
         return network_get_strv("DOMAINS", ret);
 }
 
-_public_ int sd_network_get_route_domains(char ***ret) {
+int sd_network_get_route_domains(char ***ret) {
         return network_get_strv("ROUTE_DOMAINS", ret);
 }
 
 static int network_link_get_string(int ifindex, const char *field, char **ret) {
-        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex) + 1];
+        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex)];
         _cleanup_free_ char *s = NULL;
         int r;
 
@@ -130,7 +130,7 @@ static int network_link_get_string(int ifindex, const char *field, char **ret) {
 }
 
 static int network_link_get_strv(int ifindex, const char *key, char ***ret) {
-        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex) + 1];
+        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex)];
         _cleanup_strv_free_ char **a = NULL;
         _cleanup_free_ char *s = NULL;
         int r;
@@ -161,19 +161,19 @@ static int network_link_get_strv(int ifindex, const char *key, char ***ret) {
         return r;
 }
 
-_public_ int sd_network_link_get_setup_state(int ifindex, char **state) {
+int sd_network_link_get_setup_state(int ifindex, char **state) {
         return network_link_get_string(ifindex, "ADMIN_STATE", state);
 }
 
-_public_ int sd_network_link_get_network_file(int ifindex, char **filename) {
+int sd_network_link_get_network_file(int ifindex, char **filename) {
         return network_link_get_string(ifindex, "NETWORK_FILE", filename);
 }
 
-_public_ int sd_network_link_get_operational_state(int ifindex, char **state) {
+int sd_network_link_get_operational_state(int ifindex, char **state) {
         return network_link_get_string(ifindex, "OPER_STATE", state);
 }
 
-_public_ int sd_network_link_get_required_family_for_online(int ifindex, char **state) {
+int sd_network_link_get_required_family_for_online(int ifindex, char **state) {
         _cleanup_free_ char *s = NULL;
         int r;
 
@@ -193,35 +193,35 @@ _public_ int sd_network_link_get_required_family_for_online(int ifindex, char **
         return 0;
 }
 
-_public_ int sd_network_link_get_carrier_state(int ifindex, char **state) {
+int sd_network_link_get_carrier_state(int ifindex, char **state) {
         return network_link_get_string(ifindex, "CARRIER_STATE", state);
 }
 
-_public_ int sd_network_link_get_address_state(int ifindex, char **state) {
+int sd_network_link_get_address_state(int ifindex, char **state) {
         return network_link_get_string(ifindex, "ADDRESS_STATE", state);
 }
 
-_public_ int sd_network_link_get_ipv4_address_state(int ifindex, char **state) {
+int sd_network_link_get_ipv4_address_state(int ifindex, char **state) {
         return network_link_get_string(ifindex, "IPV4_ADDRESS_STATE", state);
 }
 
-_public_ int sd_network_link_get_ipv6_address_state(int ifindex, char **state) {
+int sd_network_link_get_ipv6_address_state(int ifindex, char **state) {
         return network_link_get_string(ifindex, "IPV6_ADDRESS_STATE", state);
 }
 
-_public_ int sd_network_link_get_online_state(int ifindex, char **state) {
+int sd_network_link_get_online_state(int ifindex, char **state) {
         return network_link_get_string(ifindex, "ONLINE_STATE", state);
 }
 
-_public_ int sd_network_link_get_dhcp6_client_iaid_string(int ifindex, char **iaid) {
+int sd_network_link_get_dhcp6_client_iaid_string(int ifindex, char **iaid) {
         return network_link_get_string(ifindex, "DHCP6_CLIENT_IAID", iaid);
 }
 
-_public_ int sd_network_link_get_dhcp6_client_duid_string(int ifindex, char **duid) {
+int sd_network_link_get_dhcp6_client_duid_string(int ifindex, char **duid) {
         return network_link_get_string(ifindex, "DHCP6_CLIENT_DUID", duid);
 }
 
-_public_ int sd_network_link_get_required_for_online(int ifindex) {
+int sd_network_link_get_required_for_online(int ifindex) {
         _cleanup_free_ char *s = NULL;
         int r;
 
@@ -236,7 +236,7 @@ _public_ int sd_network_link_get_required_for_online(int ifindex) {
         return parse_boolean(s);
 }
 
-_public_ int sd_network_link_get_required_operstate_for_online(int ifindex, char **state) {
+int sd_network_link_get_required_operstate_for_online(int ifindex, char **state) {
         _cleanup_free_ char *s = NULL;
         int r;
 
@@ -257,7 +257,7 @@ _public_ int sd_network_link_get_required_operstate_for_online(int ifindex, char
         return 0;
 }
 
-_public_ int sd_network_link_get_activation_policy(int ifindex, char **policy) {
+int sd_network_link_get_activation_policy(int ifindex, char **policy) {
         _cleanup_free_ char *s = NULL;
         int r;
 
@@ -278,48 +278,48 @@ _public_ int sd_network_link_get_activation_policy(int ifindex, char **policy) {
         return 0;
 }
 
-_public_ int sd_network_link_get_llmnr(int ifindex, char **llmnr) {
+int sd_network_link_get_llmnr(int ifindex, char **llmnr) {
         return network_link_get_string(ifindex, "LLMNR", llmnr);
 }
 
-_public_ int sd_network_link_get_mdns(int ifindex, char **mdns) {
+int sd_network_link_get_mdns(int ifindex, char **mdns) {
         return network_link_get_string(ifindex, "MDNS", mdns);
 }
 
-_public_ int sd_network_link_get_dns_over_tls(int ifindex, char **dns_over_tls) {
+int sd_network_link_get_dns_over_tls(int ifindex, char **dns_over_tls) {
         return network_link_get_string(ifindex, "DNS_OVER_TLS", dns_over_tls);
 }
 
-_public_ int sd_network_link_get_dnssec(int ifindex, char **dnssec) {
+int sd_network_link_get_dnssec(int ifindex, char **dnssec) {
         return network_link_get_string(ifindex, "DNSSEC", dnssec);
 }
 
-_public_ int sd_network_link_get_dnssec_negative_trust_anchors(int ifindex, char ***nta) {
+int sd_network_link_get_dnssec_negative_trust_anchors(int ifindex, char ***nta) {
         return network_link_get_strv(ifindex, "DNSSEC_NTA", nta);
 }
 
-_public_ int sd_network_link_get_dns(int ifindex, char ***ret) {
+int sd_network_link_get_dns(int ifindex, char ***ret) {
         return network_link_get_strv(ifindex, "DNS", ret);
 }
 
-_public_ int sd_network_link_get_ntp(int ifindex, char ***ret) {
+int sd_network_link_get_ntp(int ifindex, char ***ret) {
         return network_link_get_strv(ifindex, "NTP", ret);
 }
 
-_public_ int sd_network_link_get_sip(int ifindex, char ***ret) {
+int sd_network_link_get_sip(int ifindex, char ***ret) {
         return network_link_get_strv(ifindex, "SIP", ret);
 }
 
-_public_ int sd_network_link_get_search_domains(int ifindex, char ***ret) {
+int sd_network_link_get_search_domains(int ifindex, char ***ret) {
         return network_link_get_strv(ifindex, "DOMAINS", ret);
 }
 
-_public_ int sd_network_link_get_route_domains(int ifindex, char ***ret) {
+int sd_network_link_get_route_domains(int ifindex, char ***ret) {
         return network_link_get_strv(ifindex, "ROUTE_DOMAINS", ret);
 }
 
-_public_ int sd_network_link_get_dns_default_route(int ifindex) {
-        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex) + 1];
+int sd_network_link_get_dns_default_route(int ifindex) {
+        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex)];
         _cleanup_free_ char *s = NULL;
         int r;
 
@@ -338,7 +338,7 @@ _public_ int sd_network_link_get_dns_default_route(int ifindex) {
 }
 
 static int network_link_get_ifindexes(int ifindex, const char *key, int **ret) {
-        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex) + 1];
+        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex)];
         _cleanup_free_ int *ifis = NULL;
         _cleanup_free_ char *s = NULL;
         size_t c = 0;
@@ -379,14 +379,31 @@ static int network_link_get_ifindexes(int ifindex, const char *key, int **ret) {
         return c;
 }
 
-_public_ int sd_network_link_get_carrier_bound_to(int ifindex, int **ret) {
+int sd_network_link_get_carrier_bound_to(int ifindex, int **ret) {
         return network_link_get_ifindexes(ifindex, "CARRIER_BOUND_TO", ret);
 }
 
-_public_ int sd_network_link_get_carrier_bound_by(int ifindex, int **ret) {
+int sd_network_link_get_carrier_bound_by(int ifindex, int **ret) {
         return network_link_get_ifindexes(ifindex, "CARRIER_BOUND_BY", ret);
 }
 
+int sd_network_link_get_stat(int ifindex, struct stat *ret) {
+        char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex)];
+        struct stat st;
+
+        assert_return(ifindex > 0, -EINVAL);
+
+        xsprintf(path, "/run/systemd/netif/links/%i", ifindex);
+
+        if (stat(path, &st) < 0)
+                return -errno;
+
+        if (ret)
+                *ret = st;
+
+        return 0;
+}
+
 static int MONITOR_TO_FD(sd_network_monitor *m) {
         return (int) (unsigned long) m - 1;
 }
@@ -417,7 +434,7 @@ static int monitor_add_inotify_watch(int fd) {
         return 0;
 }
 
-_public_ int sd_network_monitor_new(sd_network_monitor **m, const char *category) {
+int sd_network_monitor_new(sd_network_monitor **m, const char *category) {
         _cleanup_close_ int fd = -1;
         int k;
         bool good = false;
@@ -443,14 +460,14 @@ _public_ int sd_network_monitor_new(sd_network_monitor **m, const char *category
         return 0;
 }
 
-_public_ sd_network_monitor* sd_network_monitor_unref(sd_network_monitor *m) {
+sd_network_monitor* sd_network_monitor_unref(sd_network_monitor *m) {
         if (m)
                 (void) close_nointr(MONITOR_TO_FD(m));
 
         return NULL;
 }
 
-_public_ int sd_network_monitor_flush(sd_network_monitor *m) {
+int sd_network_monitor_flush(sd_network_monitor *m) {
         union inotify_event_buffer buffer;
         struct inotify_event *e;
         ssize_t l;
@@ -483,14 +500,14 @@ _public_ int sd_network_monitor_flush(sd_network_monitor *m) {
         return 0;
 }
 
-_public_ int sd_network_monitor_get_fd(sd_network_monitor *m) {
+int sd_network_monitor_get_fd(sd_network_monitor *m) {
 
         assert_return(m, -EINVAL);
 
         return MONITOR_TO_FD(m);
 }
 
-_public_ int sd_network_monitor_get_events(sd_network_monitor *m) {
+int sd_network_monitor_get_events(sd_network_monitor *m) {
 
         assert_return(m, -EINVAL);
 
@@ -501,7 +518,7 @@ _public_ int sd_network_monitor_get_events(sd_network_monitor *m) {
         return POLLIN;
 }
 
-_public_ int sd_network_monitor_get_timeout(sd_network_monitor *m, uint64_t *timeout_usec) {
+int sd_network_monitor_get_timeout(sd_network_monitor *m, uint64_t *timeout_usec) {
 
         assert_return(m, -EINVAL);
         assert_return(timeout_usec, -EINVAL);

src/resolve/resolved-link.c

@@ -16,6 +16,7 @@
 #include "resolved-llmnr.h"
 #include "resolved-mdns.h"
 #include "socket-netlink.h"
+#include "stat-util.h"
 #include "string-util.h"
 #include "strv.h"
 #include "tmpfile-util.h"
@@ -568,27 +569,42 @@ static int link_is_managed(Link *l) {
         return !STR_IN_SET(state, "pending", "initialized", "unmanaged");
 }
 
+static void link_enter_unmanaged(Link *l) {
+        assert(l);
+
+        /* If this link used to be managed, but is now unmanaged, flush all our settings — but only once. */
+        if (l->is_managed)
+                link_flush_settings(l);
+
+        l->is_managed = false;
+}
+
 static void link_read_settings(Link *l) {
+        struct stat st;
         int r;
 
         assert(l);
 
         /* Read settings from networkd, except when networkd is not managing this interface. */
 
+        r = sd_network_link_get_stat(l->ifindex, &st);
+        if (r == -ENOENT)
+                return link_enter_unmanaged(l);
+        if (r < 0)
+                return (void) log_link_warning_errno(l, r, "Failed to stat() networkd's link state file, ignoring: %m");
+
+        if (stat_inode_unmodified(&l->networkd_state_file_stat, &st))
+                /* The state file is unmodified. Not necessary to re-read settings. */
+                return;
+
+        /* Save the new stat for the next event. */
+        l->networkd_state_file_stat = st;
+
         r = link_is_managed(l);
-        if (r < 0) {
-                log_link_warning_errno(l, r, "Failed to determine whether the interface is managed: %m");
-                return;
-        }
-        if (r == 0) {
-
-                /* If this link used to be managed, but is now unmanaged, flush all our settings — but only once. */
-                if (l->is_managed)
-                        link_flush_settings(l);
-
-                l->is_managed = false;
-                return;
-        }
+        if (r < 0)
+                return (void) log_link_warning_errno(l, r, "Failed to determine whether the interface is managed, ignoring: %m");
+        if (r == 0)
+                return link_enter_unmanaged(l);
 
         l->is_managed = true;
 

src/resolve/resolved-link.h

@@ -1,6 +1,8 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 #pragma once
 
+#include <sys/stat.h>
+
 #include "sd-netlink.h"
 
 #include "in-addr-util.h"
@@ -65,6 +67,7 @@ struct Link {
         DnsScope *mdns_ipv4_scope;
         DnsScope *mdns_ipv6_scope;
 
+        struct stat networkd_state_file_stat;
         bool is_managed;
 
         char *ifname;

src/systemd/sd-network.h

@@ -18,6 +18,7 @@
 ***/
 
 #include <inttypes.h>
+#include <sys/stat.h>
 #include <sys/types.h>
 
 #include "_sd-common.h"
@@ -187,6 +188,8 @@ int sd_network_link_get_dhcp6_client_iaid_string(int ifindex, char **iaid);
 /* Get DHCPv6 client DUID for a given link. */
 int sd_network_link_get_dhcp6_client_duid_string(int ifindex, char **duid);
 
+int sd_network_link_get_stat(int ifindex, struct stat *ret);
+
 /* Monitor object */
 typedef struct sd_network_monitor sd_network_monitor;