| Message ID | 20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-16-554456a44a15@linutronix.de (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | timekeeping: Rework to prepare support of indenpendent PTP clocks | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Wed, Oct 9, 2024 at 1:29 AM Anna-Maria Behnsen <anna-maria@linutronix.de> wrote: > > From: Anna-Maria Behnsen <anna-maria@linutronix.de> > > Updates of the timekeeper can be done by operating on the shadow timekeeper > and afterwards copying the result into the real timekeeper. This has the > advantage, that the sequence count write protected region is kept as small > as possible. > > Convert do_settimeofday64() to use this scheme. > > That allows to use a scoped_guard() for locking the timekeeper lock as the > usage of the shadow timekeeper allows a rollback in the error case instead > of the full timekeeper update of the original code. > > Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> > --- > kernel/time/timekeeping.c | 42 ++++++++++++++++-------------------------- > 1 file changed, 16 insertions(+), 26 deletions(-) > > diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c > index 41d88f645868..cc01ad53d96d 100644 > --- a/kernel/time/timekeeping.c > +++ b/kernel/time/timekeeping.c > @@ -1479,45 +1479,35 @@ EXPORT_SYMBOL_GPL(timekeeping_clocksource_has_base); > */ > int do_settimeofday64(const struct timespec64 *ts) > { > - struct timekeeper *tk = &tk_core.timekeeper; > struct timespec64 ts_delta, xt; > - unsigned long flags; > - int ret = 0; > > if (!timespec64_valid_settod(ts)) > return -EINVAL; > > - raw_spin_lock_irqsave(&tk_core.lock, flags); > - write_seqcount_begin(&tk_core.seq); > - > - timekeeping_forward_now(tk); > - > - xt = tk_xtime(tk); > - ts_delta = timespec64_sub(*ts, xt); > + scoped_guard (raw_spinlock_irqsave, &tk_core.lock) { > + struct timekeeper *tk = &tk_core.shadow_timekeeper; nit: maybe shadow_tk instead, so it is additionally clear in the following logic which is being modified. Otherwise, Acked-by: John Stultz <jstultz@google.com>
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 41d88f645868..cc01ad53d96d 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1479,45 +1479,35 @@ EXPORT_SYMBOL_GPL(timekeeping_clocksource_has_base); */ int do_settimeofday64(const struct timespec64 *ts) { - struct timekeeper *tk = &tk_core.timekeeper; struct timespec64 ts_delta, xt; - unsigned long flags; - int ret = 0; if (!timespec64_valid_settod(ts)) return -EINVAL; - raw_spin_lock_irqsave(&tk_core.lock, flags); - write_seqcount_begin(&tk_core.seq); - - timekeeping_forward_now(tk); - - xt = tk_xtime(tk); - ts_delta = timespec64_sub(*ts, xt); + scoped_guard (raw_spinlock_irqsave, &tk_core.lock) { + struct timekeeper *tk = &tk_core.shadow_timekeeper; - if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) { - ret = -EINVAL; - goto out; - } + timekeeping_forward_now(tk); - tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta)); + xt = tk_xtime(tk); + ts_delta = timespec64_sub(*ts, xt); - tk_set_xtime(tk, ts); -out: - timekeeping_update(&tk_core, tk, TK_UPDATE_ALL | TK_MIRROR); + if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) { + timekeeping_restore_shadow(&tk_core); + return -EINVAL; + } - write_seqcount_end(&tk_core.seq); - raw_spin_unlock_irqrestore(&tk_core.lock, flags); + tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta)); + tk_set_xtime(tk, ts); + timekeeping_update_staged(&tk_core, TK_UPDATE_ALL); + } /* Signal hrtimers about time change */ clock_was_set(CLOCK_SET_WALL); - if (!ret) { - audit_tk_injoffset(ts_delta); - add_device_randomness(ts, sizeof(*ts)); - } - - return ret; + audit_tk_injoffset(ts_delta); + add_device_randomness(ts, sizeof(*ts)); + return 0; } EXPORT_SYMBOL(do_settimeofday64);