linux.git/kernel/time, branch v6.1.98

tick/nohz_full: Don't abuse smp_call_function_single() in tick_setup_device()

2024-06-21T12:35:59+00:00

commit 07c54cc5988f19c9642fd463c2dbdac7fc52f777 upstream.

After the recent commit 5097cbcb38e6 ("sched/isolation: Prevent boot crash
when the boot CPU is nohz_full") the kernel no longer crashes, but there is
another problem.

In this case tick_setup_device() calls tick_take_do_timer_from_boot() to
update tick_do_timer_cpu and this triggers the WARN_ON_ONCE(irqs_disabled)
in smp_call_function_single().

Kill tick_take_do_timer_from_boot() and just use WRITE_ONCE(), the new
comment explains why this is safe (thanks Thomas!).

Fixes: 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full")
Signed-off-by: Oleg Nesterov 
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240528122019.GA28794@redhat.com
Link: https://lore.kernel.org/all/20240522151742.GA10400@redhat.com
Signed-off-by: Greg Kroah-Hartman

timers: Rename del_timer() to timer_delete()

2024-05-17T09:56:13+00:00

[ Upstream commit bb663f0f3c396c6d05f6c5eeeea96ced20ff112e ]

The timer related functions do not have a strict timer_ prefixed namespace
which is really annoying.

Rename del_timer() to timer_delete() and provide del_timer()
as a wrapper. Document that del_timer() is not for new code.

Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: Steven Rostedt (Google) 
Reviewed-by: Jacob Keller 
Reviewed-by: Anna-Maria Behnsen 
Link: https://lore.kernel.org/r/20221123201625.015535022@linutronix.de
Stable-dep-of: 4893b8b3ef8d ("hsr: Simplify code for announcing HSR nodes timer setup")
Signed-off-by: Sasha Levin

timers: Get rid of del_singleshot_timer_sync()

2024-05-17T09:56:12+00:00

[ Upstream commit 9a5a305686971f4be10c6d7251c8348d74b3e014 ]

del_singleshot_timer_sync() used to be an optimization for deleting timers
which are not rearmed from the timer callback function.

This optimization turned out to be broken and got mapped to
del_timer_sync() about 17 years ago.

Get rid of the undocumented indirection and use del_timer_sync() directly.

No functional change.

Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: Jacob Keller 
Reviewed-by: Anna-Maria Behnsen 
Link: https://lore.kernel.org/r/20221123201624.706987932@linutronix.de
Stable-dep-of: 4893b8b3ef8d ("hsr: Simplify code for announcing HSR nodes timer setup")
Signed-off-by: Sasha Levin

timers: Rename del_timer_sync() to timer_delete_sync()

2024-04-03T13:19:23+00:00

[ Upstream commit 9b13df3fb64ee95e2397585404e442afee2c7d4f ]

The timer related functions do not have a strict timer_ prefixed namespace
which is really annoying.

Rename del_timer_sync() to timer_delete_sync() and provide del_timer_sync()
as a wrapper. Document that del_timer_sync() is not for new code.

Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: Steven Rostedt (Google) 
Reviewed-by: Jacob Keller 
Reviewed-by: Anna-Maria Behnsen 
Link: https://lore.kernel.org/r/20221123201624.954785441@linutronix.de
Stable-dep-of: 0f7352557a35 ("wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach")
Signed-off-by: Sasha Levin

timers: Use del_timer_sync() even on UP

2024-04-03T13:19:23+00:00

[ Upstream commit 168f6b6ffbeec0b9333f3582e4cf637300858db5 ]

del_timer_sync() is assumed to be pointless on uniprocessor systems and can
be mapped to del_timer() because in theory del_timer() can never be invoked
while the timer callback function is executed.

This is not entirely true because del_timer() can be invoked from interrupt
context and therefore hit in the middle of a running timer callback.

Contrary to that del_timer_sync() is not allowed to be invoked from
interrupt context unless the affected timer is marked with TIMER_IRQSAFE.
del_timer_sync() has proper checks in place to detect such a situation.

Give up on the UP optimization and make del_timer_sync() unconditionally
available.

Co-developed-by: Steven Rostedt 
Signed-off-by: Steven Rostedt 
Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: Jacob Keller 
Reviewed-by: Anna-Maria Behnsen 
Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home
Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org
Link: https://lore.kernel.org/r/20221123201624.888306160@linutronix.de
Stable-dep-of: 0f7352557a35 ("wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach")
Signed-off-by: Sasha Levin

timers: Update kernel-doc for various functions

2024-04-03T13:19:23+00:00

[ Upstream commit 14f043f1340bf30bc60af127bff39f55889fef26 ]

The kernel-doc of timer related functions is partially uncomprehensible
word salad. Rewrite it to make it useful.

Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: Jacob Keller 
Reviewed-by: Anna-Maria Behnsen 
Link: https://lore.kernel.org/r/20221123201624.828703870@linutronix.de
Stable-dep-of: 0f7352557a35 ("wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach")
Signed-off-by: Sasha Levin

timekeeping: Fix cross-timestamp interpolation for non-x86

2024-03-26T22:20:29+00:00

[ Upstream commit 14274d0bd31b4debf28284604589f596ad2e99f2 ]

So far, get_device_system_crosststamp() unconditionally passes
system_counterval.cycles to timekeeping_cycles_to_ns(). But when
interpolating system time (do_interp == true), system_counterval.cycles is
before tkr_mono.cycle_last, contrary to the timekeeping_cycles_to_ns()
expectations.

On x86, CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE will mitigate on
interpolating, setting delta to 0. With delta == 0, xtstamp->sys_monoraw
and xtstamp->sys_realtime are then set to the last update time, as
implicitly expected by adjust_historical_crosststamp(). On other
architectures, the resulting nonsense xtstamp->sys_monoraw and
xtstamp->sys_realtime corrupt the xtstamp (ts) adjustment in
adjust_historical_crosststamp().

Fix this by deriving xtstamp->sys_monoraw and xtstamp->sys_realtime from
the last update time when interpolating, by using the local variable
"cycles". The local variable already has the right value when
interpolating, unlike system_counterval.cycles.

Fixes: 2c756feb18d9 ("time: Add history to cross timestamp interface supporting slower devices")
Signed-off-by: Peter Hilber 
Signed-off-by: Thomas Gleixner 
Acked-by: John Stultz 
Link: https://lore.kernel.org/r/20231218073849.35294-4-peter.hilber@opensynergy.com
Signed-off-by: Sasha Levin

timekeeping: Fix cross-timestamp interpolation corner case decision

2024-03-26T22:20:29+00:00

[ Upstream commit 87a41130881995f82f7adbafbfeddaebfb35f0ef ]

The cycle_between() helper checks if parameter test is in the open interval
(before, after). Colloquially speaking, this also applies to the counter
wrap-around special case before > after. get_device_system_crosststamp()
currently uses cycle_between() at the first call site to decide whether to
interpolate for older counter readings.

get_device_system_crosststamp() has the following problem with
cycle_between() testing against an open interval: Assume that, by chance,
cycles == tk->tkr_mono.cycle_last (in the following, "cycle_last" for
brevity). Then, cycle_between() at the first call site, with effective
argument values cycle_between(cycle_last, cycles, now), returns false,
enabling interpolation. During interpolation,
get_device_system_crosststamp() will then call cycle_between() at the
second call site (if a history_begin was supplied). The effective argument
values are cycle_between(history_begin->cycles, cycles, cycles), since
system_counterval.cycles == interval_start == cycles, per the assumption.
Due to the test against the open interval, cycle_between() returns false
again. This causes get_device_system_crosststamp() to return -EINVAL.

This failure should be avoided, since get_device_system_crosststamp() works
both when cycles follows cycle_last (no interpolation), and when cycles
precedes cycle_last (interpolation). For the case cycles == cycle_last,
interpolation is actually unneeded.

Fix this by changing cycle_between() into timestamp_in_interval(), which
now checks against the closed interval, rather than the open interval.

This changes the get_device_system_crosststamp() behavior for three corner
cases:

1. Bypass interpolation in the case cycles == tk->tkr_mono.cycle_last,
   fixing the problem described above.

2. At the first timestamp_in_interval() call site, cycles == now no longer
   causes failure.

3. At the second timestamp_in_interval() call site, history_begin->cycles
   == system_counterval.cycles no longer causes failure.
   adjust_historical_crosststamp() also works for this corner case,
   where partial_history_cycles == total_history_cycles.

These behavioral changes should not cause any problems.

Fixes: 2c756feb18d9 ("time: Add history to cross timestamp interface supporting slower devices")
Signed-off-by: Peter Hilber 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20231218073849.35294-3-peter.hilber@opensynergy.com
Signed-off-by: Sasha Levin

timekeeping: Fix cross-timestamp interpolation on counter wrap

2024-03-26T22:20:29+00:00

[ Upstream commit 84dccadd3e2a3f1a373826ad71e5ced5e76b0c00 ]

cycle_between() decides whether get_device_system_crosststamp() will
interpolate for older counter readings.

cycle_between() yields wrong results for a counter wrap-around where after
< before < test, and for the case after < test < before.

Fix the comparison logic.

Fixes: 2c756feb18d9 ("time: Add history to cross timestamp interface supporting slower devices")
Signed-off-by: Peter Hilber 
Signed-off-by: Thomas Gleixner 
Acked-by: John Stultz 
Link: https://lore.kernel.org/r/20231218073849.35294-2-peter.hilber@opensynergy.com
Signed-off-by: Sasha Levin

time: test: Fix incorrect format specifier

2024-03-26T22:20:29+00:00

[ Upstream commit 133e267ef4a26d19c93996a874714e9f3f8c70aa ]

'days' is a s64 (from div_s64), and so should use a %lld specifier.

This was found by extending KUnit's assertion macros to use gcc's
__printf attribute.

Fixes: 276010551664 ("time: Improve performance of time64_to_tm()")
Signed-off-by: David Gow 
Tested-by: Guenter Roeck 
Reviewed-by: Justin Stitt 
Signed-off-by: Shuah Khan 
Signed-off-by: Sasha Levin