From 818b3b31e67349d8c9d4340b02661df04b5edcaf Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@amutable.com>
Date: Wed, 1 Jul 2026 11:05:27 +0200
Subject: [PATCH] time-util: use sysconf_clock_ticks_cached() at all places we
 query _SC_CLK_TCK

---
 src/basic/procfs-util.c | 10 +++-------
 src/basic/time-util.c   | 19 +++++++++----------
 src/basic/time-util.h   |  2 ++
 3 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/src/basic/procfs-util.c b/src/basic/procfs-util.c
index eaa36e3921..9ddffe2d37 100644
--- a/src/basic/procfs-util.c
+++ b/src/basic/procfs-util.c
@@ -131,7 +131,6 @@ int procfs_cpu_get_usage(nsec_t *ret) {
         _cleanup_free_ char *first_line = NULL;
         unsigned long user_ticks, nice_ticks, system_ticks, irq_ticks, softirq_ticks,
                 guest_ticks = 0, guest_nice_ticks = 0;
-        long ticks_per_second;
         uint64_t sum, gcd, a, b;
         const char *p;
         int r;
@@ -156,10 +155,7 @@ int procfs_cpu_get_usage(nsec_t *ret) {
                    &guest_nice_ticks) < 5) /* we only insist on the first five fields */
                 return -EINVAL;
 
-        ticks_per_second = sysconf(_SC_CLK_TCK);
-        if (ticks_per_second  < 0)
-                return -errno;
-        assert(ticks_per_second > 0);
+        uint64_t ticks_per_second = sysconf_clock_ticks_cached();
 
         sum = (uint64_t) user_ticks + (uint64_t) nice_ticks + (uint64_t) system_ticks +
                 (uint64_t) irq_ticks + (uint64_t) softirq_ticks +
@@ -168,8 +164,8 @@ int procfs_cpu_get_usage(nsec_t *ret) {
         /* Let's reduce this fraction before we apply it to avoid overflows when converting this to μsec */
         gcd = calc_gcd64(NSEC_PER_SEC, ticks_per_second);
 
-        a = (uint64_t) NSEC_PER_SEC / gcd;
-        b = (uint64_t) ticks_per_second / gcd;
+        a = NSEC_PER_SEC / gcd;
+        b = ticks_per_second / gcd;
 
         *ret = DIV_ROUND_UP((nsec_t) sum * (nsec_t) a, (nsec_t) b);
         return 0;
diff --git a/src/basic/time-util.c b/src/basic/time-util.c
index eb74de32c2..93173c4d91 100644
--- a/src/basic/time-util.c
+++ b/src/basic/time-util.c
@@ -1766,27 +1766,26 @@ int localtime_or_gmtime_usec(
         return 0;
 }
 
-static uint32_t sysconf_clock_ticks_cached(void) {
-        static thread_local uint32_t hz = 0;
-        long r;
+uint64_t sysconf_clock_ticks_cached(void) {
+        static thread_local uint64_t hz = 0;
 
-        if (hz == 0) {
-                r = sysconf(_SC_CLK_TCK);
+        if (hz != 0)
+                return hz;
 
-                assert(r > 0);
-                hz = r;
-        }
+        long t = sysconf(_SC_CLK_TCK);
+        assert(t > 0);
+        hz = (uint64_t) t;
 
         return hz;
 }
 
 uint32_t usec_to_jiffies(usec_t u) {
-        uint32_t hz = sysconf_clock_ticks_cached();
+        uint64_t hz = sysconf_clock_ticks_cached();
         return DIV_ROUND_UP(u, USEC_PER_SEC / hz);
 }
 
 usec_t jiffies_to_usec(uint32_t j) {
-        uint32_t hz = sysconf_clock_ticks_cached();
+        uint64_t hz = sysconf_clock_ticks_cached();
         return DIV_ROUND_UP(j * USEC_PER_SEC, hz);
 }
 
diff --git a/src/basic/time-util.h b/src/basic/time-util.h
index fdaf11edcb..fb0aab3ff5 100644
--- a/src/basic/time-util.h
+++ b/src/basic/time-util.h
@@ -201,6 +201,8 @@ static inline int parse_birth_date(const char *s, struct tm *ret) {
         return parse_calendar_date_full(s, /* allow_pre_epoch= */ true, NULL, ret);
 }
 
+uint64_t sysconf_clock_ticks_cached(void);
+
 uint32_t usec_to_jiffies(usec_t usec);
 usec_t jiffies_to_usec(uint32_t jiffies);