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3310225dfc
PROP_MAX_SHIFT should be set to <=32 on 64-bit box. This fixes two bugs in the below lines of bdi_dirty_limit(): bdi_dirty *= numerator; do_div(bdi_dirty, denominator); 1) divide error: do_div() only uses the lower 32 bit of the denominator, which may trimmed to be 0 when PROP_MAX_SHIFT > 32. 2) overflow: (bdi_dirty * numerator) could easily overflow if numerator used up to 48 bits, leaving only 16 bits to bdi_dirty Cc: <stable@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Reported-by: Ilya Tumaykin <librarian_rus@yahoo.com> Tested-by: Ilya Tumaykin <librarian_rus@yahoo.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
136 lines
3.2 KiB
C
136 lines
3.2 KiB
C
/*
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* FLoating proportions
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*
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* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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*
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* This file contains the public data structure and API definitions.
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*/
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#ifndef _LINUX_PROPORTIONS_H
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#define _LINUX_PROPORTIONS_H
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#include <linux/percpu_counter.h>
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#include <linux/spinlock.h>
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#include <linux/mutex.h>
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struct prop_global {
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/*
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* The period over which we differentiate
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*
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* period = 2^shift
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*/
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int shift;
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/*
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* The total event counter aka 'time'.
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*
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* Treated as an unsigned long; the lower 'shift - 1' bits are the
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* counter bits, the remaining upper bits the period counter.
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*/
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struct percpu_counter events;
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};
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/*
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* global proportion descriptor
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*
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* this is needed to consitently flip prop_global structures.
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*/
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struct prop_descriptor {
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int index;
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struct prop_global pg[2];
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struct mutex mutex; /* serialize the prop_global switch */
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};
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int prop_descriptor_init(struct prop_descriptor *pd, int shift);
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void prop_change_shift(struct prop_descriptor *pd, int new_shift);
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/*
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* ----- PERCPU ------
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*/
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struct prop_local_percpu {
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/*
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* the local events counter
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*/
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struct percpu_counter events;
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/*
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* snapshot of the last seen global state
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*/
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int shift;
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unsigned long period;
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raw_spinlock_t lock; /* protect the snapshot state */
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};
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int prop_local_init_percpu(struct prop_local_percpu *pl);
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void prop_local_destroy_percpu(struct prop_local_percpu *pl);
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void __prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl);
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void prop_fraction_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl,
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long *numerator, long *denominator);
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static inline
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void prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl)
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{
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unsigned long flags;
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local_irq_save(flags);
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__prop_inc_percpu(pd, pl);
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local_irq_restore(flags);
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}
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/*
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* Limit the time part in order to ensure there are some bits left for the
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* cycle counter and fraction multiply.
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*/
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#if BITS_PER_LONG == 32
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#define PROP_MAX_SHIFT (3*BITS_PER_LONG/4)
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#else
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#define PROP_MAX_SHIFT (BITS_PER_LONG/2)
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#endif
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#define PROP_FRAC_SHIFT (BITS_PER_LONG - PROP_MAX_SHIFT - 1)
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#define PROP_FRAC_BASE (1UL << PROP_FRAC_SHIFT)
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void __prop_inc_percpu_max(struct prop_descriptor *pd,
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struct prop_local_percpu *pl, long frac);
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/*
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* ----- SINGLE ------
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*/
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struct prop_local_single {
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/*
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* the local events counter
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*/
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unsigned long events;
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/*
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* snapshot of the last seen global state
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* and a lock protecting this state
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*/
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unsigned long period;
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int shift;
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raw_spinlock_t lock; /* protect the snapshot state */
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};
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#define INIT_PROP_LOCAL_SINGLE(name) \
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{ .lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock), \
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}
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int prop_local_init_single(struct prop_local_single *pl);
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void prop_local_destroy_single(struct prop_local_single *pl);
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void __prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl);
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void prop_fraction_single(struct prop_descriptor *pd, struct prop_local_single *pl,
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long *numerator, long *denominator);
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static inline
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void prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl)
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{
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unsigned long flags;
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local_irq_save(flags);
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__prop_inc_single(pd, pl);
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local_irq_restore(flags);
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}
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#endif /* _LINUX_PROPORTIONS_H */
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