linux/kernel/time, branch v3.13

sched_clock: Disable seqlock lockdep usage in sched_clock()

2014-01-12T09:14:00Z

Unfortunately the seqlock lockdep enablement can't be used in sched_clock(), since the lockdep infrastructure eventually calls into sched_clock(), which causes a deadlock. Thus, this patch changes all generic sched_clock() usage to use the raw_* methods. Acked-by: Linus Torvalds Reviewed-by: Stephen Boyd Reported-by: Krzysztof Hałasa Signed-off-by: John Stultz Cc: Uwe Kleine-König Cc: Willy Tarreau Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1388704274-5278-2-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar

nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off

2013-11-29T11:23:03Z

If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ. If CONFIG_NO_HZ=y and the nohz functionality is disabled via the command line option "nohz=off" or not enabled due to missing hardware support, then tick_nohz_get_sleep_length() returns 0. That happens because ts->sleep_length is never set in that case. Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive. Reported-by: Michal Hocko Reported-by: Borislav Petkov Signed-off-by: Thomas Gleixner

time: Fix 1ns/tick drift w/ GENERIC_TIME_VSYSCALL_OLD

2013-11-22T20:08:11Z

Since commit 1e75fa8be9f (time: Condense timekeeper.xtime into xtime_sec - merged in v3.6), there has been an problem with the error accounting in the timekeeping code, such that when truncating to nanoseconds, we round up to the next nsec, but the balancing adjustment to the ntp_error value was dropped. This causes 1ns per tick drift forward of the clock. In 3.7, this logic was isolated to only GENERIC_TIME_VSYSCALL_OLD architectures (s390, ia64, powerpc). The fix is simply to balance the accounting and to subtract the added nanosecond from ntp_error. This allows the internal long-term clock steering to keep the clock accurate. While this fix removes the regression added in 1e75fa8be9f, the ideal solution is to move away from GENERIC_TIME_VSYSCALL_OLD and use the new VSYSCALL method, which avoids entirely the nanosecond granular rounding, and the resulting short-term clock adjustment oscillation needed to keep long term accurate time. [ jstultz: Many thanks to Martin for his efforts identifying this subtle bug, and providing the fix. ] Originally-from: Martin Schwidefsky Cc: Tony Luck Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Andy Lutomirski Cc: Paul Turner Cc: Steven Rostedt Cc: Richard Cochran Cc: Prarit Bhargava Cc: Fenghua Yu Cc: Thomas Gleixner Cc: stable #v3.6+ Link: http://lkml.kernel.org/r/1385149491-20307-1-git-send-email-john.stultz@linaro.org Signed-off-by: John Stultz Signed-off-by: Thomas Gleixner

tick: Document tick_do_timer_cpu

2013-11-19T13:59:50Z

Taken straight from a tglx email ;) Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner

NOHZ: Check for nohz active instead of nohz enabled

2013-11-19T13:59:50Z

RCU and the fine grained idle time accounting functions check tick_nohz_enabled. But that variable is merily telling that NOHZ has been enabled in the config and not been disabled on the command line. But it does not tell anything about nohz being active. That's what all this should check for. Matthew reported, that the idle accounting on his old P1 machine showed bogus values, when he enabled NOHZ in the config and did not disable it on the kernel command line. The reason is that his machine uses (refined) jiffies as a clocksource which explains why the "fine" grained accounting went into lala land, because it depends on when the system goes and leaves idle relative to the jiffies increment. Provide a tick_nohz_active indicator and let RCU and the accounting code use this instead of tick_nohz_enable. Reported-and-tested-by: Matthew Whitehead Signed-off-by: Thomas Gleixner Reviewed-by: Steven Rostedt Reviewed-by: Paul E. McKenney Cc: john.stultz@linaro.org Cc: mwhitehe@redhat.com Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311132052240.30673@ionos.tec.linutronix.de

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-11-12T01:36:00Z

Pull timer changes from Ingo Molnar: "Main changes in this cycle were: - Updated full dynticks support. - Event stream support for architected (ARM) timers. - ARM clocksource driver updates. - Move arm64 to using the generic sched_clock framework & resulting cleanup in the generic sched_clock code. - Misc fixes and cleanups" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits) x86/time: Honor ACPI FADT flag indicating absence of a CMOS RTC clocksource: sun4i: remove IRQF_DISABLED clocksource: sun4i: Report the minimum tick that we can program clocksource: sun4i: Select CLKSRC_MMIO clocksource: Provide timekeeping for efm32 SoCs clocksource: em_sti: convert to clk_prepare/unprepare time: Fix signedness bug in sysfs_get_uname() and its callers timekeeping: Fix some trivial typos in comments alarmtimer: return EINVAL instead of ENOTSUPP if rtcdev doesn't exist clocksource: arch_timer: Do not register arch_sys_counter twice timer stats: Add a 'Collection: active/inactive' line to timer usage statistics sched_clock: Remove sched_clock_func() hook arch_timer: Move to generic sched_clock framework clocksource: tcb_clksrc: Remove IRQF_DISABLED clocksource: tcb_clksrc: Improve driver robustness clocksource: tcb_clksrc: Replace clk_enable/disable with clk_prepare_enable/disable_unprepare clocksource: arm_arch_timer: Use clocksource for suspend timekeeping clocksource: dw_apb_timer_of: Mark a few more functions as __init clocksource: Put nodes passed to CLOCKSOURCE_OF_DECLARE callbacks centrally arm: zynq: Enable arm_global_timer ...

clockevents: Sanitize ticks to nsec conversion

2013-10-23T10:51:21Z

Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use clockevents_config_and_register() where possible" caused a regression for some of the converted subarchs. The reason is, that the clockevents core code converts the minimal hardware tick delta to a nanosecond value for core internal usage. This conversion is affected by integer math rounding loss, so the backwards conversion to hardware ticks will likely result in a value which is less than the configured hardware limitation. The affected subarchs used their own workaround (SIGH!) which got lost in the conversion. The solution for the issue at hand is simple: adding evt->mult - 1 to the shifted value before the integer divison in the core conversion function takes care of it. But this only works for the case where for the scaled math mult/shift pair "mult <= 1 << shift" is true. For the case where "mult > 1 << shift" we can apply the rounding add only for the minimum delta value to make sure that the backward conversion is not less than the given hardware limit. For the upper bound we need to omit the rounding add, because the backwards conversion is always larger than the original latch value. That would violate the upper bound of the hardware device. Though looking closer at the details of that function reveals another bogosity: The upper bounds check is broken as well. Checking for a resulting "clc" value greater than KTIME_MAX after the conversion is pointless. The conversion does: u64 clc = (latch << evt->shift) / evt->mult; So there is no sanity check for (latch << evt->shift) exceeding the 64bit boundary. The latch argument is "unsigned long", so on a 64bit arch the handed in argument could easily lead to an unnoticed shift overflow. With the above rounding fix applied the calculation before the divison is: u64 clc = (latch << evt->shift) + evt->mult - 1; So we need to make sure, that neither the shift nor the rounding add is overflowing the u64 boundary. [ukl: move assignment to rnd after eventually changing mult, fix build issue and correct comment with the right math] Signed-off-by: Thomas Gleixner Cc: Russell King - ARM Linux Cc: Marc Kleine-Budde Cc: nicolas.ferre@atmel.com Cc: Marc Pignat Cc: john.stultz@linaro.org Cc: kernel@pengutronix.de Cc: Ronald Wahl Cc: LAK Cc: Ludovic Desroches Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König

time: Fix signedness bug in sysfs_get_uname() and its callers

2013-10-18T23:45:58Z

sysfs_get_uname() is erroneously declared as returning size_t even though it may return a negative value, specifically -EINVAL. Its callers then check whether its return value is less than zero and indeed that is never the case for size_t. This patch changes sysfs_get_uname() to return ssize_t and makes sure its callers use ssize_t accordingly. Signed-off-by: Patrick Palka [jstultz: Didn't apply cleanly, as a similar partial fix was also applied so had to resolve the collisions] Signed-off-by: John Stultz

timekeeping: Fix some trivial typos in comments

2013-10-18T23:30:17Z

Fix some typos in timekeeping comments. Signed-off-by: Xie XiuQi [jstultz: Commit message tweaks] Signed-off-by: John Stultz

alarmtimer: return EINVAL instead of ENOTSUPP if rtcdev doesn't exist

2013-10-18T23:23:58Z

Fedora Ruby maintainer reported latest Ruby doesn't work on Fedora Rawhide on ARM. (http://bugs.ruby-lang.org/issues/9008) Because of, commit 1c6b39ad3f (alarmtimers: Return -ENOTSUPP if no RTC device is present) intruduced to return ENOTSUPP when clock_get{time,res} can't find a RTC device. However this is incorrect. First, ENOTSUPP isn't exported to userland (ENOTSUP or EOPNOTSUP are the closest userland equivlents). Second, Posix and Linux man pages agree that clock_gettime and clock_getres should return EINVAL if clk_id argument is invalid. While the arugment that the clockid is valid, but just not supported on this hardware could be made, this is just a technicality that doesn't help userspace applicaitons, and only complicates error handling. Thus, this patch changes the code to use EINVAL. Cc: Thomas Gleixner Cc: Frederic Weisbecker Cc: stable #3.0 and up Reported-by: Vit Ondruch Signed-off-by: KOSAKI Motohiro [jstultz: Tweaks to commit message to include full rational] Signed-off-by: John Stultz