linux/kernel/time/tick-common.c, branch v2.6.38

clockevents: Prevent oneshot mode when broadcast device is periodic

2011-02-26T08:45:28Z

When the per cpu timer is marked CLOCK_EVT_FEAT_C3STOP, then we only can switch into oneshot mode, when the backup broadcast device supports oneshot mode as well. Otherwise we would try to switch the broadcast device into an unsupported mode unconditionally. This went unnoticed so far as the current available broadcast devices support oneshot mode. Seth unearthed this problem while debugging and working around an hpet related BIOS wreckage. Add the necessary check to tick_is_oneshot_available(). Reported-and-tested-by: Seth Forshee Signed-off-by: Thomas Gleixner LKML-Reference: Cc: stable@kernel.org # .21 ->

core: Replace __get_cpu_var with __this_cpu_read if not used for an address.

2010-12-17T14:07:19Z

__get_cpu_var() can be replaced with this_cpu_read and will then use a single read instruction with implied address calculation to access the correct per cpu instance. However, the address of a per cpu variable passed to __this_cpu_read() cannot be determined (since it's an implied address conversion through segment prefixes). Therefore apply this only to uses of __get_cpu_var where the address of the variable is not used. Cc: Pekka Enberg Cc: Hugh Dickins Cc: Thomas Gleixner Acked-by: H. Peter Anvin Signed-off-by: Christoph Lameter Signed-off-by: Tejun Heo

clockevents: Convert to raw_spinlock

2009-12-14T22:55:34Z

Convert locks which cannot be sleeping locks in preempt-rt to raw_spinlocks. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Acked-by: Ingo Molnar

clockevents: Make tick_device_lock static

2009-12-14T22:55:34Z

Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Acked-by: Ingo Molnar

clockevents: prevent endless loop in tick_handle_periodic()

2009-05-02T08:22:27Z

tick_handle_periodic() can lock up hard when a one shot clock event device is used in combination with jiffies clocksource. Avoid an endless loop issue by requiring that a highres valid clocksource be installed before we call tick_periodic() in a loop when using ONESHOT mode. The result is we will only increment jiffies once per interrupt until a continuous hardware clocksource is available. Without this, we can run into a endless loop, where each cycle through the loop, jiffies is updated which increments time by tick_period or more (due to clock steering), which can cause the event programming to think the next event was before the newly incremented time and fail causing tick_periodic() to be called again and the whole process loops forever. [ Impact: prevent hard lock up ] Signed-off-by: John Stultz Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner Cc: stable@kernel.org

hrtimers: allow the hot-unplugging of all cpus

2009-01-30T21:35:29Z

Impact: fix CPU hotplug hang on Power6 testbox On architectures that support offlining all cpus (at least powerpc/pseries), hot-unpluging the tick_do_timer_cpu can result in a system hang. This comes from the fact that if the cpu going down happens to be the cpu doing the tick, then as the tick_do_timer_cpu handover happens after the cpu is dead (via the CPU_DEAD notification), we're left without ticks, jiffies are frozen and any task relying on timers (msleep, ...) is stuck. That's particularly the case for the cpu looping in __cpu_die() waiting for the dying cpu to be dead. This patch addresses this by having the tick_do_timer_cpu handover happen earlier during the CPU_DYING notification. For this, a new clockevent notification type is introduced (CLOCK_EVT_NOTIFY_CPU_DYING) which is triggered in hrtimer_cpu_notify(). Signed-off-by: Sebastien Dugue Cc: Signed-off-by: Ingo Molnar

cpumask: convert kernel time functions

2008-12-31T23:42:25Z

Impact: Use new APIs Convert kernel/time functions to use struct cpumask *. Note the ugly bitmap declarations in tick-broadcast.c. These should be cpumask_var_t, but there was no obvious initialization function to put the alloc_cpumask_var() calls in. This was safe. (Eventually 'struct cpumask' will be undefined for CONFIG_CPUMASK_OFFSTACK, so we use a bitmap here to show we really mean it). Signed-off-by: Rusty Russell Signed-off-by: Mike Travis

cpumask: convert struct clock_event_device to cpumask pointers.

2008-12-13T10:50:26Z

Impact: change calling convention of existing clock_event APIs struct clock_event_timer's cpumask field gets changed to take pointer, as does the ->broadcast function. Another single-patch change. For safety, we BUG_ON() in clockevents_register_device() if it's not set. Signed-off-by: Rusty Russell Cc: Ingo Molnar

cpumask: make irq_set_affinity() take a const struct cpumask

2008-12-13T10:50:26Z

Impact: change existing irq_chip API Not much point with gentle transition here: the struct irq_chip's setaffinity method signature needs to change. Fortunately, not widely used code, but hits a few architectures. Note: In irq_select_affinity() I save a temporary in by mangling irq_desc[irq].affinity directly. Ingo, does this break anything? (Folded in fix from KOSAKI Motohiro) Signed-off-by: Rusty Russell Signed-off-by: Mike Travis Reviewed-by: Grant Grundler Acked-by: Ingo Molnar Cc: ralf@linux-mips.org Cc: grundler@parisc-linux.org Cc: jeremy@xensource.com Cc: KOSAKI Motohiro

clockevents: prevent mode mismatch on cpu online

2008-09-23T09:38:53Z

Impact: timer hang on CPU online observed on AMD C1E systems When a CPU is brought online then the broadcast machinery can be in the one shot state already. Check this and setup the timer device of the new CPU in one shot mode so the broadcast code can pick up the next_event value correctly. Another AMD C1E oddity, as we switch to broadcast immediately and not after the full bring up via the ACPI cpu idle code. Signed-off-by: Thomas Gleixner