98197d3de5
commitfe32d3cd5eupstream. These functions check should_resched() before unlocking spinlock/bh-enable: preempt_count always non-zero => should_resched() always returns false. cond_resched_lock() worked iff spin_needbreak is set. This patch adds argument "preempt_offset" to should_resched(). preempt_count offset constants for that: PREEMPT_DISABLE_OFFSET - offset after preempt_disable() PREEMPT_LOCK_OFFSET - offset after spin_lock() SOFTIRQ_DISABLE_OFFSET - offset after local_bh_distable() SOFTIRQ_LOCK_OFFSET - offset after spin_lock_bh() Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Graf <agraf@suse.de> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes:bdb4380658("sched: Extract the basic add/sub preempt_count modifiers") Link: http://lkml.kernel.org/r/20150715095204.12246.98268.stgit@buzz Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
126 lines
3.8 KiB
C
126 lines
3.8 KiB
C
#ifndef LINUX_PREEMPT_MASK_H
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#define LINUX_PREEMPT_MASK_H
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#include <linux/preempt.h>
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/*
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* We put the hardirq and softirq counter into the preemption
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* counter. The bitmask has the following meaning:
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*
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* - bits 0-7 are the preemption count (max preemption depth: 256)
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* - bits 8-15 are the softirq count (max # of softirqs: 256)
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*
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* The hardirq count could in theory be the same as the number of
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* interrupts in the system, but we run all interrupt handlers with
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* interrupts disabled, so we cannot have nesting interrupts. Though
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* there are a few palaeontologic drivers which reenable interrupts in
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* the handler, so we need more than one bit here.
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*
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* PREEMPT_MASK: 0x000000ff
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* SOFTIRQ_MASK: 0x0000ff00
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* HARDIRQ_MASK: 0x000f0000
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* NMI_MASK: 0x00100000
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* PREEMPT_ACTIVE: 0x00200000
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*/
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#define PREEMPT_BITS 8
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#define SOFTIRQ_BITS 8
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#define HARDIRQ_BITS 4
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#define NMI_BITS 1
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#define PREEMPT_SHIFT 0
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#define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS)
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#define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
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#define NMI_SHIFT (HARDIRQ_SHIFT + HARDIRQ_BITS)
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#define __IRQ_MASK(x) ((1UL << (x))-1)
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#define PREEMPT_MASK (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
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#define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
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#define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
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#define NMI_MASK (__IRQ_MASK(NMI_BITS) << NMI_SHIFT)
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#define PREEMPT_OFFSET (1UL << PREEMPT_SHIFT)
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#define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT)
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#define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT)
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#define NMI_OFFSET (1UL << NMI_SHIFT)
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#define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET)
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#define PREEMPT_ACTIVE_BITS 1
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#define PREEMPT_ACTIVE_SHIFT (NMI_SHIFT + NMI_BITS)
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#define PREEMPT_ACTIVE (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
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#define hardirq_count() (preempt_count() & HARDIRQ_MASK)
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#define softirq_count() (preempt_count() & SOFTIRQ_MASK)
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#define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
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| NMI_MASK))
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/*
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* Are we doing bottom half or hardware interrupt processing?
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* Are we in a softirq context? Interrupt context?
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* in_softirq - Are we currently processing softirq or have bh disabled?
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* in_serving_softirq - Are we currently processing softirq?
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*/
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#define in_irq() (hardirq_count())
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#define in_softirq() (softirq_count())
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#define in_interrupt() (irq_count())
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#define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET)
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/*
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* Are we in NMI context?
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*/
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#define in_nmi() (preempt_count() & NMI_MASK)
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/*
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* The preempt_count offset after preempt_disable();
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*/
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#if defined(CONFIG_PREEMPT_COUNT)
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# define PREEMPT_DISABLE_OFFSET PREEMPT_OFFSET
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#else
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# define PREEMPT_DISABLE_OFFSET 0
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#endif
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/*
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* The preempt_count offset after spin_lock()
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*/
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#define PREEMPT_LOCK_OFFSET PREEMPT_DISABLE_OFFSET
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/*
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* The preempt_count offset needed for things like:
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*
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* spin_lock_bh()
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*
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* Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and
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* softirqs, such that unlock sequences of:
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*
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* spin_unlock();
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* local_bh_enable();
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*
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* Work as expected.
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*/
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#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_LOCK_OFFSET)
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/*
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* Are we running in atomic context? WARNING: this macro cannot
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* always detect atomic context; in particular, it cannot know about
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* held spinlocks in non-preemptible kernels. Thus it should not be
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* used in the general case to determine whether sleeping is possible.
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* Do not use in_atomic() in driver code.
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*/
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#define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
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/*
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* Check whether we were atomic before we did preempt_disable():
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* (used by the scheduler, *after* releasing the kernel lock)
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*/
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#define in_atomic_preempt_off() \
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((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_DISABLE_OFFSET)
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#ifdef CONFIG_PREEMPT_COUNT
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# define preemptible() (preempt_count() == 0 && !irqs_disabled())
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#else
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# define preemptible() 0
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#endif
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#endif /* LINUX_PREEMPT_MASK_H */
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