From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 14 Feb 2023 15:13:59 +0000 (+0100)
Subject: resolved: flush caches on memory pressure and support SIGRTMIN+18
X-Git-Tag: v254-rc1~1142^2~17
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=bb3517181b025e74c1f263e1b2d326f1e12abafb;p=thirdparty%2Fsystemd.git

resolved: flush caches on memory pressure and support SIGRTMIN+18
---

diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 6c6c98566f1..3d456bbc9ab 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -543,6 +543,30 @@ static int manager_sigrtmin1(sd_event_source *s, const struct signalfd_siginfo *
         return 0;
 }
 
+static int manager_memory_pressure(sd_event_source *s, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+
+        log_info("Under memory pressure, flushing caches.");
+
+        manager_flush_caches(m, LOG_INFO);
+        sd_event_trim_memory();
+
+        return 0;
+}
+
+static int manager_memory_pressure_listen(Manager *m) {
+        int r;
+
+        assert(m);
+
+        r = sd_event_add_memory_pressure(m->event, NULL, manager_memory_pressure, m);
+        if (r < 0)
+                log_full_errno(ERRNO_IS_NOT_SUPPORTED(r) || ERRNO_IS_PRIVILEGE(r) || (r == -EHOSTDOWN )? LOG_DEBUG : LOG_NOTICE, r,
+                               "Failed to install memory pressure event source, ignoring: %m");
+
+        return 0;
+}
+
 int manager_new(Manager **ret) {
         _cleanup_(manager_freep) Manager *m = NULL;
         int r;
@@ -572,6 +596,9 @@ int manager_new(Manager **ret) {
                 .need_builtin_fallbacks = true,
                 .etc_hosts_last = USEC_INFINITY,
                 .read_etc_hosts = true,
+
+                .sigrtmin18_info.memory_pressure_handler = manager_memory_pressure,
+                .sigrtmin18_info.memory_pressure_userdata = m,
         };
 
         r = dns_trust_anchor_load(&m->trust_anchor);
@@ -621,6 +648,10 @@ int manager_new(Manager **ret) {
         if (r < 0)
                 return r;
 
+        r = manager_memory_pressure_listen(m);
+        if (r < 0)
+                return r;
+
         r = manager_connect_bus(m);
         if (r < 0)
                 return r;
@@ -628,6 +659,7 @@ int manager_new(Manager **ret) {
         (void) sd_event_add_signal(m->event, &m->sigusr1_event_source, SIGUSR1, manager_sigusr1, m);
         (void) sd_event_add_signal(m->event, &m->sigusr2_event_source, SIGUSR2, manager_sigusr2, m);
         (void) sd_event_add_signal(m->event, &m->sigrtmin1_event_source, SIGRTMIN+1, manager_sigrtmin1, m);
+        (void) sd_event_add_signal(m->event, NULL, SIGRTMIN+18, sigrtmin18_handler, &m->sigrtmin18_info);
 
         manager_cleanup_saved_user(m);
 
diff --git a/src/resolve/resolved-manager.h b/src/resolve/resolved-manager.h
index 98d90e05b38..f8f3af6fd05 100644
--- a/src/resolve/resolved-manager.h
+++ b/src/resolve/resolved-manager.h
@@ -7,6 +7,7 @@
 #include "sd-netlink.h"
 #include "sd-network.h"
 
+#include "common-signal.h"
 #include "hashmap.h"
 #include "list.h"
 #include "ordered-set.h"
@@ -156,6 +157,8 @@ struct Manager {
         LIST_HEAD(SocketGraveyard, socket_graveyard);
         SocketGraveyard *socket_graveyard_oldest;
         size_t n_socket_graveyard;
+
+        struct sigrtmin18_info sigrtmin18_info;
 };
 
 /* Manager */
diff --git a/src/resolve/resolved.c b/src/resolve/resolved.c
index d3bc9027522..f9d3281509d 100644
--- a/src/resolve/resolved.c
+++ b/src/resolve/resolved.c
@@ -67,7 +67,7 @@ static int run(int argc, char *argv[]) {
                         return log_error_errno(r, "Failed to drop privileges: %m");
         }
 
-        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGUSR1, SIGUSR2, SIGRTMIN+1, -1) >= 0);
+        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGUSR1, SIGUSR2, SIGRTMIN+1, SIGRTMIN+18, -1) >= 0);
 
         r = manager_new(&m);
         if (r < 0)