linux/kernel/time, branch v4.19

clocksource: Revert "Remove kthread"

2018-09-06T21:38:35Z

I turns out that the silly spawn kthread from worker was actually needed. clocksource_watchdog_kthread() cannot be called directly from clocksource_watchdog_work(), because clocksource_select() calls timekeeping_notify() which uses stop_machine(). One cannot use stop_machine() from a workqueue() due lock inversions wrt CPU hotplug. Revert the patch but add a comment that explain why we jump through such apparently silly hoops. Fixes: 7197e77abcb6 ("clocksource: Remove kthread") Reported-by: Siegfried Metz Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Tested-by: Niklas Cassel Tested-by: Kevin Shanahan Tested-by: viktor_jaegerskuepper@freenet.de Tested-by: Siegfried Metz Cc: rafael.j.wysocki@intel.com Cc: len.brown@intel.com Cc: diego.viola@gmail.com Cc: rui.zhang@intel.com Cc: bjorn.andersson@linaro.org Link: https://lkml.kernel.org/r/20180905084158.GR24124@hirez.programming.kicks-ass.net

Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2018-08-21T20:47:29Z

Pull core signal handling updates from Eric Biederman: "It was observed that a periodic timer in combination with a sufficiently expensive fork could prevent fork from every completing. This contains the changes to remove the need for that restart. This set of changes is split into several parts: - The first part makes PIDTYPE_TGID a proper pid type instead something only for very special cases. The part starts using PIDTYPE_TGID enough so that in __send_signal where signals are actually delivered we know if the signal is being sent to a a group of processes or just a single process. - With that prep work out of the way the logic in fork is modified so that fork logically makes signals received while it is running appear to be received after the fork completes" * 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (22 commits) signal: Don't send signals to tasks that don't exist signal: Don't restart fork when signals come in. fork: Have new threads join on-going signal group stops fork: Skip setting TIF_SIGPENDING in ptrace_init_task signal: Add calculate_sigpending() fork: Unconditionally exit if a fatal signal is pending fork: Move and describe why the code examines PIDNS_ADDING signal: Push pid type down into complete_signal. signal: Push pid type down into __send_signal signal: Push pid type down into send_signal signal: Pass pid type into do_send_sig_info signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task signal: Pass pid type into group_send_sig_info signal: Pass pid and pid type into send_sigqueue posix-timers: Noralize good_sigevent signal: Use PIDTYPE_TGID to clearly store where file signals will be sent pid: Implement PIDTYPE_TGID pids: Move the pgrp and session pid pointers from task_struct to signal_struct kvm: Don't open code task_pid in kvm_vcpu_ioctl pids: Compute task_tgid using signal->leader_pid ...

Merge branch 'parisc-4.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux

2018-08-14T02:18:02Z

Pull parisc updates from Helge Deller: - parisc now uses the generic dma_noncoherent_ops implementation (Christoph Hellwig) - further memory barrier and spinlock improvements (John David Anglin) - prepare removal of current_text_addr() functions (Nick Desaulniers) - improve kernel stack unwinding on parisc (me) - drop ENOTSUP which was defined on parisc only (me) * 'parisc-4.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Fix and improve kernel stack unwinding parisc: Remove unnecessary barriers from spinlock.h parisc: Remove ordered stores from syscall.S parisc: prefer _THIS_IP_ and _RET_IP_ statement expressions parisc: Add HAVE_REGS_AND_STACK_ACCESS_API feature parisc: Drop architecture-specific ENOTSUP define parisc: use generic dma_noncoherent_ops parisc: always use flush_kernel_dcache_range for DMA cache maintainance parisc: merge pcx_dma_ops and pcxl_dma_ops

Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-08-14T01:28:19Z

Pull x86 timer updates from Thomas Gleixner: "Early TSC based time stamping to allow better boot time analysis. This comes with a general cleanup of the TSC calibration code which grew warts and duct taping over the years and removes 250 lines of code. Initiated and mostly implemented by Pavel with help from various folks" * 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits) x86/kvmclock: Mark kvm_get_preset_lpj() as __init x86/tsc: Consolidate init code sched/clock: Disable interrupts when calling generic_sched_clock_init() timekeeping: Prevent false warning when persistent clock is not available sched/clock: Close a hole in sched_clock_init() x86/tsc: Make use of tsc_calibrate_cpu_early() x86/tsc: Split native_calibrate_cpu() into early and late parts sched/clock: Use static key for sched_clock_running sched/clock: Enable sched clock early sched/clock: Move sched clock initialization and merge with generic clock x86/tsc: Use TSC as sched clock early x86/tsc: Initialize cyc2ns when tsc frequency is determined x86/tsc: Calibrate tsc only once ARM/time: Remove read_boot_clock64() s390/time: Remove read_boot_clock64() timekeeping: Default boot time offset to local_clock() timekeeping: Replace read_boot_clock64() with read_persistent_wall_and_boot_offset() s390/time: Add read_persistent_wall_and_boot_offset() x86/xen/time: Output xen sched_clock time from 0 x86/xen/time: Initialize pv xen time in init_hypervisor_platform() ...

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

2018-08-13T20:02:31Z

Pull timer updates from Thomas Gleixner: "The timers departement more or less proudly presents: - More Y2038 timekeeping work mostly in the core code. The work is slowly, but steadily targeting the actuall syscalls. - Enhanced timekeeping suspend/resume support by utilizing clocksources which do not stop during suspend, but are otherwise not the main timekeeping clocksources. - Make NTP adjustmets more accurate and immediate when the frequency is set directly and not incrementally. - Sanitize the overrung handing of posix timers - A new timer driver for Mediatek SoCs - The usual pile of fixes and updates all over the place" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) clockevents: Warn if cpu_all_mask is used as cpumask tick/broadcast-hrtimer: Use cpu_possible_mask for ce_broadcast_hrtimer clocksource/drivers/arm_arch_timer: Fix bogus cpu_all_mask usage clocksource: ti-32k: Remove CLOCK_SOURCE_SUSPEND_NONSTOP flag timers: Clear timer_base::must_forward_clk with timer_base::lock held clocksource/drivers/sprd: Register one always-on timer to compensate suspend time clocksource/drivers/timer-mediatek: Add support for system timer clocksource/drivers/timer-mediatek: Convert the driver to timer-of clocksource/drivers/timer-mediatek: Use specific prefix for GPT clocksource/drivers/timer-mediatek: Rename mtk_timer to timer-mediatek clocksource/drivers/timer-mediatek: Add system timer bindings clocksource/drivers: Set clockevent device cpumask to cpu_possible_mask time: Introduce one suspend clocksource to compensate the suspend time time: Fix extra sleeptime injection when suspend fails timekeeping/ntp: Constify some function arguments ntp: Use kstrtos64 for s64 variable ntp: Remove redundant arguments timer: Fix coding style ktime: Provide typesafe ktime_to_ns() hrtimer: Improve kernel message printing ...

parisc: Drop architecture-specific ENOTSUP define

2018-08-13T07:30:41Z

parisc is the only Linux architecture which has defined a value for ENOTSUP. All other architectures #define ENOTSUP as EOPNOTSUPP in their libc headers. Having an own value for ENOTSUP which is different than EOPNOTSUPP often gives problems with userspace programs which expect both to be the same. One such example is a build error in the libuv package, as can be seen in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=900237. Since we dropped HP-UX support, there is no real benefit in keeping an own value for ENOTSUP. This patch drops the parisc value for ENOTSUP from the kernel sources. glibc needs no patch, it reuses the exported headers. Signed-off-by: Helge Deller

clockevents: Warn if cpu_all_mask is used as cpumask

2018-08-02T12:55:53Z

Using cpu_all_mask in clockevents cpumask may result in issues while comparing multiple clockevent devices to choose the preferred one. On one of the platforms with 2 system (i.e. non per-CPU) timers with different ratings, having cpu_all_mask for one of the device resulted in a boot hang due to a endless loop in clockevents_notify_released() as both were clocksources were selected as preferred. In order to prevent such issues in the future, warn if any clockevent driver sets cpu_all_mask as it's cpumask and just override it to use cpu_possible_mask. All the existing occurrences of cpu_all_mask are already replaced with cpu_possible_mask. Signed-off-by: Sudeep Holla Signed-off-by: Thomas Gleixner Cc: linux-arm-kernel@lists.infradead.org Link: https://lkml.kernel.org/r/1531308264-24220-3-git-send-email-sudeep.holla@arm.com

tick/broadcast-hrtimer: Use cpu_possible_mask for ce_broadcast_hrtimer

2018-08-02T12:55:52Z

This is the last instance of cpu_all_mask usage in the core framework. Replace it with cpu_possible_mask like all other instances in the clockevent drivers. This makes it possible to add a warning in the core clockevents_register_device on usage of cpu_all_mask from any clockevent drivers in the future. Signed-off-by: Sudeep Holla Signed-off-by: Thomas Gleixner Cc: linux-arm-kernel@lists.infradead.org Link: https://lkml.kernel.org/r/1531308264-24220-2-git-send-email-sudeep.holla@arm.com

timers: Clear timer_base::must_forward_clk with timer_base::lock held

2018-08-02T10:52:38Z

timer_base::must_forward_clock is indicating that the base clock might be stale due to a long idle sleep. The forwarding of the base clock takes place in the timer softirq or when a timer is enqueued to a base which is idle. If the enqueue of timer to an idle base happens from a remote CPU, then the following race can happen: CPU0 CPU1 run_timer_softirq mod_timer base = lock_timer_base(timer); base->must_forward_clk = false if (base->must_forward_clk) forward(base); -> skipped enqueue_timer(base, timer, idx); -> idx is calculated high due to stale base unlock_timer_base(timer); base = lock_timer_base(timer); forward(base); The root cause is that timer_base::must_forward_clk is cleared outside the timer_base::lock held region, so the remote queuing CPU observes it as cleared, but the base clock is still stale. This can cause large granularity values for timers, i.e. the accuracy of the expiry time suffers. Prevent this by clearing the flag with timer_base::lock held, so that the forwarding takes place before the cleared flag is observable by a remote CPU. Signed-off-by: Gaurav Kohli Signed-off-by: Thomas Gleixner Cc: john.stultz@linaro.org Cc: sboyd@kernel.org Cc: linux-arm-msm@vger.kernel.org Link: https://lkml.kernel.org/r/1533199863-22748-1-git-send-email-gkohli@codeaurora.org

nohz: Fix local_timer_softirq_pending()

2018-07-31T20:08:44Z

local_timer_softirq_pending() checks whether the timer softirq is pending with: local_softirq_pending() & TIMER_SOFTIRQ. This is wrong because TIMER_SOFTIRQ is the softirq number and not a bitmask. So the test checks for the wrong bit. Use BIT(TIMER_SOFTIRQ) instead. Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()") Signed-off-by: Anna-Maria Gleixner Signed-off-by: Thomas Gleixner Reviewed-by: Paul E. McKenney Reviewed-by: Daniel Bristot de Oliveira Acked-by: Frederic Weisbecker Cc: bigeasy@linutronix.de Cc: peterz@infradead.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180731161358.29472-1-anna-maria@linutronix.de