Re: [PATCH 06/14] vdso/gettimeofday: Return bool from clock_gettime() helpers

On 01.07.2025 10:58, Thomas Weißschuh wrote:

The internal helpers are effectively using boolean results, while pretending to use error numbers.

Switch the return type to bool for more clarity.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de

lib/vdso/gettimeofday.c | 58 +++++++++++++++++++++++++------------------------ 1 file changed, 30 insertions(+), 28 deletions(-)

This patch landed in today's linux-next as commit fcc8e46f768f ("vdso/gettimeofday: Return bool from clock_gettime() helpers"). In my tests I found that it causes serious problem with hwclock operation on some of my ARM 32bit test boards. I observe that calling "hwclock -w -f /dev/rtc0" never ends on those boards. Disabling vdso support (by removing ARM architected timer) fixes this issue.

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c index 9b77f23566f6a35887d4c9aaefc61a971131b499..c5266532a097c06f33d12e345c695357d75abf42 100644 --- a/lib/vdso/gettimeofday.c +++ b/lib/vdso/gettimeofday.c @@ -82,8 +82,8 @@ const struct vdso_time_data *__arch_get_vdso_u_timens_data(const struct vdso_tim #endif /* CONFIG_GENERIC_VDSO_DATA_STORE */ static __always_inline -int do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,

•    clockid_t clk, struct __kernel_timespec *ts)
  

+bool do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,

•     clockid_t clk, struct __kernel_timespec *ts)
  

  { const struct vdso_time_data *vd = __arch_get_vdso_u_timens_data(vdns); const struct timens_offset *offs = &vcns->offset[clk];

@@ -103,11 +103,11 @@ int do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *v seq = vdso_read_begin(vc); if (unlikely(!vdso_clocksource_ok(vc)))

• 	return -1;
  

• 	return false;
  

cycles = __arch_get_hw_counter(vc->clock_mode, vd); if (unlikely(!vdso_cycles_ok(cycles)))

• 	return -1;
  

• 	return false;
  

  ns = vdso_calc_ns(vc, cycles, vdso_ts->nsec); sec = vdso_ts->sec; } while (unlikely(vdso_read_retry(vc, seq)));

@@ -123,7 +123,7 @@ int do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *v ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); ts->tv_nsec = ns;

• return 0;

• return true; } #else static __always_inline

@@ -133,16 +133,16 @@ const struct vdso_time_data *__arch_get_vdso_u_timens_data(const struct vdso_tim } static __always_inline -int do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,

•    clockid_t clk, struct __kernel_timespec *ts)
  

+bool do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,

•     clockid_t clk, struct __kernel_timespec *ts)
  

  {

• return -EINVAL;

• return false; } #endif

static __always_inline -int do_hres(const struct vdso_time_data *vd, const struct vdso_clock *vc,

•    clockid_t clk, struct __kernel_timespec *ts)
  

+bool do_hres(const struct vdso_time_data *vd, const struct vdso_clock *vc,

•     clockid_t clk, struct __kernel_timespec *ts)
  

  { const struct vdso_timestamp *vdso_ts = &vc->basetime[clk]; u64 cycles, sec, ns;

@@ -150,7 +150,7 @@ int do_hres(const struct vdso_time_data *vd, const struct vdso_clock *vc, /* Allows to compile the high resolution parts out */ if (!__arch_vdso_hres_capable())

• return -1;
  

• return false;
  

do { /* @@ -173,11 +173,11 @@ int do_hres(const struct vdso_time_data *vd, const struct vdso_clock *vc, smp_rmb(); if (unlikely(!vdso_clocksource_ok(vc)))

• 	return -1;
  

• 	return false;
  

cycles = __arch_get_hw_counter(vc->clock_mode, vd); if (unlikely(!vdso_cycles_ok(cycles)))

• 	return -1;
  

• 	return false;
  

  ns = vdso_calc_ns(vc, cycles, vdso_ts->nsec); sec = vdso_ts->sec; } while (unlikely(vdso_read_retry(vc, seq)));

@@ -189,13 +189,13 @@ int do_hres(const struct vdso_time_data *vd, const struct vdso_clock *vc, ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); ts->tv_nsec = ns;

• return 0;

• return true; }

#ifdef CONFIG_TIME_NS static __always_inline -int do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,

•      clockid_t clk, struct __kernel_timespec *ts)
  

+bool do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,

•       clockid_t clk, struct __kernel_timespec *ts)
  

  { const struct vdso_time_data *vd = __arch_get_vdso_u_timens_data(vdns); const struct timens_offset *offs = &vcns->offset[clk];

@@ -223,20 +223,20 @@ int do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock */ ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec); ts->tv_nsec = nsec;

• return 0;

• return true; } #else static __always_inline

-int do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,

•      clockid_t clk, struct __kernel_timespec *ts)
  

+bool do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,

•       clockid_t clk, struct __kernel_timespec *ts)
  

  {

• return -1;

• return false; } #endif

static __always_inline -int do_coarse(const struct vdso_time_data *vd, const struct vdso_clock *vc,

•      clockid_t clk, struct __kernel_timespec *ts)
  

+bool do_coarse(const struct vdso_time_data *vd, const struct vdso_clock *vc,

•       clockid_t clk, struct __kernel_timespec *ts)
  

  { const struct vdso_timestamp *vdso_ts = &vc->basetime[clk]; u32 seq;

@@ -258,10 +258,10 @@ int do_coarse(const struct vdso_time_data *vd, const struct vdso_clock *vc, ts->tv_nsec = vdso_ts->nsec; } while (unlikely(vdso_read_retry(vc, seq)));

• return 0;

• return true; }

-static __always_inline int +static __always_inline bool __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock, struct __kernel_timespec *ts) { @@ -270,7 +270,7 @@ __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock, /* Check for negative values or invalid clocks */ if (unlikely((u32) clock >= MAX_CLOCKS))

• return -1;
  

• return false;
  

/* * Convert the clockid to a bitmask and use it to check which @@ -284,7 +284,7 @@ __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock, else if (msk & VDSO_RAW) vc = &vc[CS_RAW]; else

• return -1;
  

• return false;
  

return do_hres(vd, vc, clock, ts); } @@ -293,9 +293,11 @@ static __maybe_unused int __cvdso_clock_gettime_data(const struct vdso_time_data *vd, clockid_t clock, struct __kernel_timespec *ts) {

• int ret = __cvdso_clock_gettime_common(vd, clock, ts);

• bool ok;

• if (unlikely(ret))

• ok = __cvdso_clock_gettime_common(vd, clock, ts);
• if (unlikely(!ok)) return clock_gettime_fallback(clock, ts); return 0; }

Best regards