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* clockevents: Sanitize min_delta_ns adjustment and prevent overflowsThomas Gleixner2010-03-121-0/+2
| | | | | | | | | | | | | | The current logic which handles clock events programming failures can increase min_delta_ns unlimited and even can cause overflows. Sanitize it by: - prevent zero increase when min_delta_ns == 1 - limiting min_delta_ns to a jiffie - bail out if the jiffie limit is hit - add retries stats for /proc/timer_list so we can gather data Reported-by: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* nohz: Allow 32-bit machines to sleep for more than 2.15 secondsJon Hunter2009-11-131-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the dynamic tick code, "max_delta_ns" (member of the "clock_event_device" structure) represents the maximum sleep time that can occur between timer events in nanoseconds. The variable, "max_delta_ns", is defined as an unsigned long which is a 32-bit integer for 32-bit machines and a 64-bit integer for 64-bit machines (if -m64 option is used for gcc). The value of max_delta_ns is set by calling the function "clockevent_delta2ns()" which returns a maximum value of LONG_MAX. For a 32-bit machine LONG_MAX is equal to 0x7fffffff and in nanoseconds this equates to ~2.15 seconds. Hence, the maximum sleep time for a 32-bit machine is ~2.15 seconds, where as for a 64-bit machine it will be many years. This patch changes the type of max_delta_ns to be "u64" instead of "unsigned long" so that this variable is a 64-bit type for both 32-bit and 64-bit machines. It also changes the maximum value returned by clockevent_delta2ns() to KTIME_MAX. Hence this allows a 32-bit machine to sleep for longer than ~2.15 seconds. Please note that this patch also changes "min_delta_ns" to be "u64" too and although this is unnecessary, it makes the patch simpler as it avoids to fixup all callers of clockevent_delta2ns(). [ tglx: changed "unsigned long long" to u64 as we use this data type through out the time code ] Signed-off-by: Jon Hunter <jon-hunter@ti.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <1250617512-23567-3-git-send-email-jon-hunter@ti.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* clocksource: Provide a generic mult/shift factor calculationThomas Gleixner2009-11-131-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | MIPS has two functions to calculcate the mult/shift factors for clock sources and clock events at run time. ARM needs such functions as well. Implement a function which calculates the mult/shift factors based on the frequencies to which and from which is converted. The function also has a parameter to specify the minimum conversion range in seconds. This range is guaranteed not to produce a 64bit overflow when a value is multiplied with the calculated mult factor. The larger the conversion range the less becomes the conversion accuracy. Provide two inline wrappers which handle clock events and clock sources. For clock events the "from" frequency is nano seconds per second which corresponds to 1GHz and "to" is the device frequency. For clock sources "from" is the device frequency and "to" is nano seconds per second. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Mikael Pettersson <mikpe@it.uu.se> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Linus Walleij <linus.walleij@stericsson.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20091111134229.766673305@linutronix.de>
* clockevents: Use u32 for mult and shift factorsThomas Gleixner2009-11-131-2/+2
| | | | | | | | | | | | | | | | | The mult and shift factors of clock events differ in their data type from those of clock sources for no reason. u32 is sufficient for both. shift is always <= 32 and mult is limited to 2^32-1 to avoid 64bit multiplication overflows in the conversion. Preparatory patch for a generic mult/shift factor calculation function. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Mikael Pettersson <mikpe@it.uu.se> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Linus Walleij <linus.walleij@stericsson.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20091111134229.725664788@linutronix.de>
* hrtimer: Fix migration expiry checkThomas Gleixner2009-07-101-9/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The timer migration expiry check should prevent the migration of a timer to another CPU when the timer expires before the next event is scheduled on the other CPU. Migrating the timer might delay it because we can not reprogram the clock event device on the other CPU. But the code implementing that check has two flaws: - for !HIGHRES the check compares the expiry value with the clock events device expiry value which is wrong for CLOCK_REALTIME based timers. - the check is racy. It holds the hrtimer base lock of the target CPU, but the clock event device expiry value can be modified nevertheless, e.g. by an timer interrupt firing. The !HIGHRES case is easy to fix as we can enqueue the timer on the cpu which was selected by the load balancer. It runs the idle balancing code once per jiffy anyway. So the maximum delay for the timer is the same as when we keep the tick on the current cpu going. In the HIGHRES case we can get the next expiry value from the hrtimer cpu_base of the target CPU and serialize the update with the cpu_base lock. This moves the lock section in hrtimer_interrupt() so we can set next_event to KTIME_MAX while we are handling the expired timers and set it to the next expiry value after we handled the timers under the base lock. While the expired timers are processed timer migration is blocked because the expiry time of the timer is always <= KTIME_MAX. Also remove the now useless clockevents_get_next_event() function. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* timers: Logic to move non pinned timersArun R Bharadwaj2009-05-131-0/+9
| | | | | | | | | | | | | | | | | | | | * Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]: This patch migrates all non pinned timers and hrtimers to the current idle load balancer, from all the idle CPUs. Timers firing on busy CPUs are not migrated. While migrating hrtimers, care should be taken to check if migrating a hrtimer would result in a latency or not. So we compare the expiry of the hrtimer with the next timer interrupt on the target cpu and migrate the hrtimer only if it expires *after* the next interrupt on the target cpu. So, added a clockevents_get_next_event() helper function to return the next_event on the target cpu's clock_event_device. [ tglx: cleanups and simplifications ] Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* hrtimers: allow the hot-unplugging of all cpusSebastien Dugue2009-01-301-0/+1
| | | | | | | | | | | | | | | | | | | | | | | 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 <sebastien.dugue@bull.net> Cc: <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* cpumask: convert struct clock_event_device to cpumask pointers.Rusty Russell2008-12-131-2/+2
| | | | | | | | | | | | | 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 <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@elte.hu>
* clockevents: prevent clockevent event_handler ending up handler_noopVenkatesh Pallipadi2008-09-051-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a ordering related problem with clockevents code, due to which clockevents_register_device() called after tickless/highres switch will not work. The new clockevent ends up with clockevents_handle_noop as event handler, resulting in no timer activity. The problematic path seems to be * old device already has hrtimer_interrupt as the event_handler * new clockevent device registers with a higher rating * tick_check_new_device() is called * clockevents_exchange_device() gets called * old->event_handler is set to clockevents_handle_noop * tick_setup_device() is called for the new device * which sets new->event_handler using the old->event_handler which is noop. Change the ordering so that new device inherits the proper handler. This does not have any issue in normal case as most likely all the clockevent devices are setup before the highres switch. But, can potentially be affecting some corner case where HPET force detect happens after the highres switch. This was a problem with HPET in MSI mode code that we have been experimenting with. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* clockevents: introduce force broadcast notifierThomas Gleixner2007-10-141-0/+1
| | | | | | | | | | | | | | | | The 64bit SMP bootup is slightly different to the 32bit one. It enables the boot CPU local APIC timer before all CPUs are brought up. Some AMD C1E systems have the C1E feature flag only set in the secondary CPU. Due to the early enable of the boot CPU local APIC timer the APIC timer is registered as a fully functional device. When we detect the wreckage during the bringup of the secondary CPU, we need to force the boot CPU into broadcast mode. Add a new notifier reason and implement the force broadcast in the clock events layer. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* clockevents: Allow build w/o run-tine usage for migration purposesThomas Gleixner2007-10-121-2/+6
| | | | | | | | | | Migration aid to allow preparatory patches which introduce not yet used parts of clock events code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
* clockevents: Remove unused inline functionThomas Gleixner2007-10-121-1/+0
| | | | | | | Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
* timer: remove clockevents_unregister_notifierMiao Xie2007-08-111-1/+0
| | | | | | | | | | I find a function(clockevents_unregister_notifier) which is not called by anything in tree. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* clockevents: fix resume logicThomas Gleixner2007-07-211-0/+1
| | | | | | | | | | | | | | | | | | | | We need to make sure, that the clockevent devices are resumed, before the tick is resumed. The current resume logic does not guarantee this. Add CLOCK_EVT_MODE_RESUME and call the set mode functions of the clock event devices before resuming the tick / oneshot functionality. Fixup the existing users. Thanks to Nigel Cunningham for tracking down a long standing thinko, which affected the jinxed VAIO. [akpm@linux-foundation.org: xen build fix] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* clockevents: remove prototypes of removed functionsThomas Gleixner2007-07-211-4/+0
| | | | | | | Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* clockchips.h: kernel-doc fixSergei Shtylyov2007-05-081-5/+5
| | | | | | | | | | Fix misnamed fields of 'struct clock_event_device' in the kernel-doc comment. Convert the acronyms to uppercase, while at it... Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] clockevents: add core functionalityThomas Gleixner2007-02-161-0/+142
Architectures register their clock event devices, in the clock events core. Users of the clockevents core can get clock event devices for their use. The clockevents core code provides notification mechanisms for various clock related management events. This allows to control the clock event devices without the architectures having to worry about the details of function assignment. This is also a preliminary for high resolution timers and dynamic ticks to allow the core code to control the clock functionality without intrusive changes to the architecture code. [Fixes-by: Ingo Molnar <mingo@elte.hu>] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: john stultz <johnstul@us.ibm.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>